Arbuscular mycorrhizal ( AM ) symbioses are mutualistic associations between soil fungi and most vascular plants .

Modulation of the hormonal and transcriptional profiles , including changes related to defense signalling , has been reported in many host plants during AM symbioses .

These changes have been often related to the improved stress tolerance common in mycorrhizal plants .

However , results on the alterations in phytohormones content and their role on the symbiosis are controversial .

Here , an integrative analysis of the response of phylogenetically diverse plants ( i.e. , tomato , soybean , and maize ) to two mycorrhizal fungi -Funneliformis mosseae and Rhizophagus irregularis- was performed .

The analysis of the defense-related hormones salicylic acid , abscisic acid , and jasmonates , and the expression of marker genes of the pathways they regulate , revealed significant changes in the roots of mycorrhizal plants .

These changes depended on both the plant and the AM fungus ( AMF ) involved .

However , general trends can be identified : roots associated with the most effective colonizer R. irregularis showed fewer changes in these defense-related traits , while the colonization by F. mosseae led to significant modifications in all plants tested .

The up-regulation of the jasmonate pathway by F. mosseae was found to be highly conserved among the different plant species , suggesting an important role of jasmonates during this AM interaction .

Our study evidences a strong influence of the AMF genotype on the modulation of host defense signalling , and offers hints on the role of these changes in the symbiosis .


The synthesis of proteinase inhibitor proteins in response to wounding is a defensive response against pest and pathogen attacks .

Wounding of leaves results in the release of a mobile wound signal which induces proteinase inhibitor synthesis throughout the plant .

The signal transduction pathway regulating this response is not fully understood , but several compounds have been identified which are capable of inducing proteinase inhibitor synthesis in tomato and potato leaves .

These compounds include cell wall fragments of both plant and pathogen origin [ 1 - 3 ] , abscisic acid [ 4 ] , jasmonic acid [ 5 ] and , most recently , an 18-amino-acid polypeptide , called systemin , isolated from tomato leaves [ 6 ] .

In this chapter , we describe the properties of systemin and its precursor prosystemin , and we summarize the evidence supporting a role for systemin as an initial signal that regulates proteinase inhibitor synthesis in response to wounding .


BACKGROUND : Besides fibers , cotton plants also produce a large amount of seeds with a high oil and protein content .

The use of these seeds is restricted by their high contents of the terpenoid gossypol , which is harmful to humans and livestock .

Using a genetic engineering approach , " Ultra-low gossypol cottonseed " ( ULGCS ) plants were produced by knocking down an enzyme that catalyzes the formation of a precursor of gossypol .

This was accomplished via RNAi-mediated silencing of the target gene using a seed-specific α-globulin promotor .

Since gossypol is also a crucial defense mechanism against leaf-feeding herbivores , ULGCS plants might possess lower herbivore resistance than non-engineered plants .

Therefore , we tested the constitutive and inducible direct insect resistance of two ULGCS cotton lines against the African cotton leafworm , Spodoptera littoralis .

RESULT : The herbivore was equally affected by both ULGCS lines and the control ( Coker 312 ) line when feeding on fully expanded true leaves from undamaged plants and plants induced by jasmonic acid .

When plants were induced by caterpillar-damage , however , S. littoralis larvae performed better on the ULGCS plants .

Terpenoid analyses revealed that the ULGCS lines were equally inducible as the control plants .

Levels of terpenoids were always lower in one of the two lines .

In the case of cotyledons , caterpillars performed better on ULGCS cotton than on conventional cotton .

This was likely caused by reduced levels of gossypol in ULGCS cotyledons .

CONCLUSION : Despite those effects , the insect resistance of ULGSC cotton can be considered as largely intact and the plants may , therefore , be an interesting alternative to conventional cotton varieties .


The abscisic acid (ABA)- , stress- , and ripening-induced ( ASR ) protein is a plant-specific hydrophilic transcriptional factor involved in fruit ripening and the abiotic stress response .

To date , there have been no studies on the role of ASR genes in delayed flowering time .

Here , we found that the ASR from banana , designated as MaASR , was preferentially expressed in the banana female flowers from the eighth , fourth , and first cluster of the inflorescence .

MaASR transgenic lines ( L14 and L38 ) had a clear delayed-flowering phenotype .

The number of rosette leaves , sepals , and pedicel trichomes in L14 and L38 was greater than in the wild type ( WT ) under long day ( LD ) conditions .

The period of buds , mid-flowers , and full bloom of L14 and L38 appeared later than the WT .

cDNA microarray and quantitative real-time PCR ( qRT-PCR ) analyses revealed that overexpression of MaASR delays flowering through reduced expression of several genes , including photoperiod pathway genes , vernalization pathway genes , gibberellic acid pathway genes , and floral integrator genes , under short days ( SD ) for 28 d ( from vegetative to reproductive transition stage ) ; however , the expression of the autonomous pathway genes was not affected .

This study provides the first evidence of a role for ASR genes in delayed flowering time in plants .


Beneficial soil microorganisms can affect plant growth and resistance by the production of volatile organic compounds ( VOCs ) .

Yet , little is known on how VOCs from soil-borne plant pathogens affect plant growth and resistance .

Here we show that VOCs released from mycelium and sclerotia of the fungal root pathogen Rhizoctonia solani enhance growth and accelerate development of Arabidopsis thaliana .

Seedlings briefly exposed to the fungal VOCs showed similar phenotypes , suggesting that enhanced biomass and accelerated development are primed already at early developmental stages .

Fungal VOCs did not affect plant resistance to infection by the VOC-producing pathogen itself but reduced aboveground resistance to the herbivore Mamestra brassicae .

Transcriptomics of A. thaliana revealed that genes involved in auxin signaling were up-regulated , whereas ethylene and jasmonic acid signaling pathways were down-regulated by fungal VOCs .

Mutants disrupted in these pathways showed similar VOC-mediated growth responses as the wild-type A. thaliana , suggesting that other yet unknown pathways play a more prominent role .

We postulate that R. solani uses VOCs to predispose plants for infection from a distance by altering root architecture and enhancing root biomass .

Alternatively , plants may use enhanced root growth upon fungal VOC perception to sacrifice part of the root biomass and accelerate development and reproduction to survive infection .


The effect of elicitation with arachidonic and jasmonic acids on the production of phenolic compounds as well as the antioxidant and anti-inflammatory properties of phenolic extracts of wheatgrass was evaluated .

The qualitative and quantitative analysis of phenolic compounds carried out with the UPLC-MS technique indicated that luteolin and apigenin derivatives were the dominant flavonoids , while ferulic acid derivatives and syringic acid were the main components in the phenolic acid fraction in the wheatgrass .

No qualitative changes in the examined phenolic compounds were observed in the case of the control and elicited plants , while there was an increase in the content of some compounds .

The antioxidant activity increased in the elicited samples ( with the exception of reducing power ) and this elevation was partially correlated with the increase in the polyphenol content in the studied plants .

Elicitation with 0.01 µM arachidonic acid also caused improvement of potential anti-inflammatory properties of the wheatgrass .


Salicylic acid ( SA ) , jasmonic acid ( JA ) , ethylene ( ET ) , and their interactions mediate plant responses to pathogen and herbivore attack .

JA-SA and JA-ET cross-signaling are well studied , but little is known about SA-ET cross-signaling in plant-herbivore interactions .

When the specialist herbivore tobacco hornworm ( Manduca sexta ) attacks Nicotiana attenuata , rapid and transient JA and ET bursts are elicited without significantly altering wound-induced SA levels .

In contrast , attack from the generalist beet armyworm ( Spodoptera exigua ) results in comparatively lower JA and ET bursts , but amplified SA bursts .

These phytohormone responses are mimicked when the species ' larval oral secretions ( OS(Se ) and OS(Ms ) ) are added to puncture wounds .

Fatty acid-amino acid conjugates elicit the JA and ET bursts , but not the SA burst .

OS(Se ) had enhanced glucose oxidase activity ( but not beta-glucosidase activity ) , which was sufficient to elicit the SA burst and attenuate the JA and ET levels .

It is known that SA antagonizes JA ; glucose oxidase activity and associated hydrogen peroxide also antagonizes the ET burst .

We examined the OS(Ms)-elicited SA burst in plants impaired in their ability to elicit JA ( antisense [as]-lox3 ) and ET ( inverted repeat [ir]-aco ) bursts and perceive ET ( 35s-etr1b ) after fatty acid-amino acid conjugate elicitation , which revealed that both ET and JA bursts antagonize the SA burst .

Treating wild-type plants with ethephone and 1-methylcyclopropane confirmed these results and demonstrated the central role of the ET burst in suppressing the OS(Ms)-elicited SA burst .

By suppressing the SA burst , the ET burst likely facilitates unfettered JA-mediated defense activation in response to herbivores that otherwise would elicit SA .


The effect of calcium on the secretion of α-amylase ( EC 3.2.1.1 ) and other hydrolases from aleurone layers of barley ( Hordeum vulgare L. cv . Himalaya ) was studied .

Withdrawal of Ca(2 + ) from the incubation medium of aleurone layers preincubated in 5 μM gibberellic acid ( GA3 ) and 5 mM CaCl2 results in a 70 - 80 % reduction in the secretion of α-amylase activity to the incubation medium .

Agar-gel electrophoresis shows that the reduction in α-amylase activity following Ca(2 + ) withdrawal is correlated with the disappearance of group B isoenzymes from the incubation medium .

The secretion of isoenzymes of group A is unaffected by Ca(2 + ) .

The addition of Ca(2 + ) stimulates the secretion of group-B isoenzymes but has no measurable effect on either the α-amylase activity or the isoenzyme pattern of aleurone-layer extracts .

Pulse-labelling experiments with [(35)S]methionine show that Ca(2 + ) withdrawal results in a reduction in the secretion of labelled polypeptides into the incubation medium .

Immunochemical studies also show that , in the absence of Ca(2 + ) , α-amylase isoenzymes of group B are not secreted into the incubation medium .

In addition to its effect on α-amylase , Ca(2 + ) influences the secretion of other proteins including several acid hydrolases .

The secretion of these other proteins shows the same dependence on Ca(2 + ) concentration as does that of α-amylase .

Other cations can promote the secretion of α-amylase to less and varying extents .

Strontium is 85 % as effective as Ca(2 + ) while Ba(2 + ) is only 10 % as effective .

We conclude that Ca(2 + ) regulates the secretion of enzymes and other proteins from the aleurone layer of barley .


Herbivore-induced plant volatiles ( HIPVs ) are commonly emitted from plants after herbivore attack .

These HIPVs are mainly regulated by the defensive plant hormone jasmonic acid ( JA ) and its volatile derivative methyl jasmonate ( MeJA ) .

Over the past 3 decades researchers have documented that HIPVs can repel or attract herbivores , attract the natural enemies of herbivores , and in some cases they can induce or prime plant defenses prior to herbivore attack .

In a recent paper , I reported that feeding by gypsy moth caterpillars , exogenous MeJA application , and mechanical damage induce the emissions of volatiles from blueberry plants , albeit differently .

In addition , blueberry branches respond to HIPVs emitted from neighboring branches of the same plant by increasing the levels of JA and resistance to herbivores ( i.e. , direct plant defenses ) , and by priming volatile emissions ( i.e. , indirect plant defenses ) .

Similar findings have been reported recently for sagebrush , poplar , and lima beans .

Here , I describe a push-pull method for collecting blueberry volatiles induced by herbivore ( gypsy moth ) feeding , exogenous MeJA application , and mechanical damage .

The volatile collection unit consists of a 4 L volatile collection chamber , a 2-piece guillotine , an air delivery system that purifies incoming air , and a vacuum system connected to a trap filled with Super-Q adsorbent to collect volatiles .

Volatiles collected in Super-Q traps are eluted with dichloromethane and then separated and quantified using Gas Chromatography ( GC ) .

This volatile collection method was used in my study to investigate the volatile response of undamaged branches to exposure to volatiles from herbivore-damaged branches within blueberry plants .

Briefly , undamaged blueberry branches are exposed to HIPVs from neighboring branches within the same plant .

Using the same techniques described above , volatiles emitted from branches after exposure to HIPVs are collected and analyzed .


The activities of (±)-abscisic acid and a number of compounds derived from p-coumaric acid and coumarin and their interaction with gibberellic acid in the control of the elongation of the first wheat leaf are examined .

(±)-Abscisic acid strongly inhibits leaf growth in the presence as well as in the absence of gibberellic acid , but the inhibition is greater in the presence of gibberellic acid ( 3 μg/l already have an observable effect ) .

Among other compounds , only ferulic acid and coumarin significantly reduce leaf elongation , and they are effective only at high concentrations ( 1.44 · 10(-4 ) M/l ) .


The large WRKY transcription factor family is mainly involved in regulating plant immune responses .

Arabidopsis WRKY33 is a key transcriptional regulator of hormonal and metabolic processes towards Botrytis cinerea strain 2100 infection and is essential for resistance .

In contrast to B. cinerea strain 2100 , the strain B05.10 is virulent on wild-type ( WT ) Col-0 Arabidopsis plants highlighting the genetic diversity within this pathogen species .

We analysed how early WRKY33-dependent responses are affected upon infection with strain B05.10 and found that most of these responses were strongly dampened during this interaction .

Ectopic expression of WRKY33 resulted in complete resistance towards this strain indicating that virulence of B05.10 , at least partly , depends on suppressing WRKY33 expression/protein accumulation .

As a consequence , the expression levels of direct WRKY33 target genes , including those involved in the biosynthesis of camalexin , were also reduced upon infection .

Concomitantly , elevated levels of the phytohormone abscisic acid ( ABA ) were observed .

Molecular and genetic studies revealed that ABA negatively influences defence to B05.10 and effects jasmonic acid/ethylene ( JA/ET ) and salicylic acid ( SA ) levels .

Susceptibility/resistance was determined by the antagonistic effect of ABA on JA , and this crosstalk required suppressing WRKY33 functions at early infection stages .

This indicates that B. cinerea B05.10 promotes disease by suppressing WRKY33-mediated host defences .


Ozone layer depletion leads to elevated ultraviolet-B ( UV-B ) radiation , which affects plant growth ; however , little is known about the relationship between root growth and signaling molecules in roots .

Therefore , in this work , simulated UV-B radiation was used to study the effects of elevated UV-B radiation on root growth of soybean seedlings and changes in the content of signaling molecules in roots .

The results showed that compared with the control , the 2.63 kJ m(-2 ) d(-1 ) and 6.17 kJ m(-2 ) d(-1 ) elevated UV-B radiation treatments inhibited root growth , and root growth parameters ( total root length , root surface area , root volume , average diameter , root tip number , and root dry weight ) all decreased .

For root signaling molecules , the content of nitric oxide , reactive oxygen species , abscisic acid , salicylic acid , and jasmonic acid increased , and the content of auxin , cytokinin , and gibberellin decreased .

The above indices changed more significantly under the 6.17 kJ m(-2 ) d(-1 ) treatment .

After withdrawal of the exposure , the above indices could be restored to a certain extent .

These data indicated that UV-B radiation interfered with root growth by affecting the content of signaling molecules in roots , and the degree of the effects was related to the intensity of UV-B radiation .

The results from this study provide a theoretical basis for studying the preliminary mechanism of elevated UV-B radiation on root growth and possible pathways that can mitigate UV-B radiation damage for root growth .

ONE SENTENCE SUMMARY : The effects of elevated UV-B on root growth of soybean seedlings were regulated by signaling molecules , and the degree of the effects was related to the intensity of UV-B radiation .


A highly sensitive and accurate multiplex gas chromatography-mass spectrometry (GC-MS/MS)-technique is reported for the quantitative analysis of acidic phytohormones in Arabidopsis thaliana and other plant species .

The optimized setup allows the routine processing and analysis of between 20 mg and 5 g of tissue .

The protocol was designed and the equipment used was chosen to facilitate implementation of the method into other laboratories and to provide access to state-of-the-art analytical tools for the acidic phytohormones and related signaling molecules .


Beet necrotic yellow vein virus ( BNYVV ) and Beet soil-borne mosaic virus ( BSBMV ) are closely related species , but disease development induced in their host sugar beet displays striking differences .

Beet necrotic yellow vein virus induces excessive lateral root ( LR ) formation , whereas BSBMV-infected roots appear asymptomatic .

A comparative transcriptome analysis was performed to elucidate transcriptomic changes associated with disease development .

Many differentially expressed genes ( DEGs ) were specific either to BNYVV or BSBMV , although both viruses shared a high number of DEGs .

Auxin biosynthesis pathways displayed a stronger activation by BNYVV compared to BSBMV-infected plants .

Several genes regulated by auxin signalling and required for LR formation were exclusively altered by BNYVV .

Both viruses reprogrammed the transcriptional network , but a large number of transcription factors involved in plant defence were upregulated in BNYVV-infected plants .

A strong activation of pathogenesis-related proteins by both viruses suggests a salicylic acid or jasmonic acid mediated-defence response , but the data also indicate that both viruses counteract the SA-mediated defence .

The ethylene signal transduction pathway was strongly downregulated which probably increases the susceptibility of sugar beet to Benyvirus infection .

Our study provides a deeper insight into the interaction of BNYVV and BSBMV with the economically important crop sugar beet .


Plants respond to proximate neighbors with a suite of responses that comprise the shade avoidance syndrome .

These phytochrome-mediated responses include hyponasty ( i.e. a more vertical orientation of leaves ) and enhanced stem and petiole elongation .

We showed recently that ethylene-insensitive tobacco ( Nicotiana tabacum ) plants ( Tetr ) have reduced responses to neighbors , showing an important role for this gaseous plant hormone in shade avoidance .

Here , we investigate interactions between phytochrome signaling and ethylene action in shade avoidance responses .

Furthermore , we investigate if ethylene acts in these responses through an interaction with the GA class of hormones .

Low red to far-red light ratios ( R : FR ) enhanced ethylene production in wild-type tobacco , resulting in shade avoidance responses , whereas ethylene-insensitive plants showed reduced shade avoidance responses .

Plants with inhibited GA production showed hardly any shade avoidance responses at all to either a low R : FR or increased ethylene concentrations .

Furthermore , low R : FR enhanced the responsiveness of hyponasty and stem elongation in both wild-type and Tetr plants to applied GA(3 ) , with the stem elongation process being more responsive to GA(3 ) in the wild type than in Tetr .

We conclude that phytochrome-mediated shade avoidance responses involve ethylene action , at least partly by modulating GA action .


In nature , herbivorous insects and plant pathogens are generally abundant when plants are flowering .

Thus , plants face a diversity of attackers during their reproductive phase .

Plant responses to one attacker can interfere with responses to a second attacker , and phytohormones that orchestrate plant reproduction are also involved in resistance to insect and pathogen attack .

We quantified phytohormonal responses of flowering plants exposed to single or dual attack and studied resistance mechanisms of plants in the flowering stage .

Flowering Brassica nigra were exposed to either a chewing caterpillar , a phloem-feeding aphid or a bacterial pathogen , and plant hormonal responses were compared with dual attack situations .

We quantified phytohormones in inflorescences and leaves , and determined the consequences of hormonal changes for components of direct and indirect plant resistance .

Caterpillars were the main inducers of jasmonates in inflorescences , and the phytohormonal profile of leaves was not affected by either insect or pathogen attack .

Dual attack increased plant resistance to caterpillars , but compromised resistance to aphids .

Parasitoid performance was negatively correlated with the performance of their hosts .

We conclude that plants prioritize resistance of reproductive tissues over vegetative tissues , and that a chewing herbivore species is the main driver of responses in flowering B. nigra .


The hemibiotrophic fungus Zymoseptoria tritici causes Septoria tritici blotch disease of wheat ( Triticum aestivum ) .

Pathogen reproduction on wheat occurs without cell penetration , suggesting that dynamic and intimate intercellular communication occurs between fungus and plant throughout the disease cycle .

We used deep RNA sequencing and metabolomics to investigate the physiology of plant and pathogen throughout an asexual reproductive cycle of Z. tritici on wheat leaves .

Over 3,000 pathogen genes , more than 7,000 wheat genes , and more than 300 metabolites were differentially regulated .

Intriguingly , individual fungal chromosomes contributed unequally to the overall gene expression changes .

Early transcriptional down-regulation of putative host defense genes was detected in inoculated leaves .

There was little evidence for fungal nutrient acquisition from the plant throughout symptomless colonization by Z. tritici , which may instead be utilizing lipid and fatty acid stores for growth .

However , the fungus then subsequently manipulated specific plant carbohydrates , including fructan metabolites , during the switch to necrotrophic growth and reproduction .

This switch coincided with increased expression of jasmonic acid biosynthesis genes and large-scale activation of other plant defense responses .

Fungal genes encoding putative secondary metabolite clusters and secreted effector proteins were identified with distinct infection phase-specific expression patterns , although functional analysis suggested that many have overlapping/redundant functions in virulence .

The pathogenic lifestyle of Z. tritici on wheat revealed through this study , involving initial defense suppression by a slow-growing extracellular and nutritionally limited pathogen followed by defense ( hyper ) activation during reproduction , reveals a subtle modification of the conceptual definition of hemibiotrophic plant infection .


Two slightly differing cDNA clones corresponding to the wound-inducible form of a previously characterized seed myrosinase-associated protein ( MyAP ) have been isolated from Brassica napus L. The transcripts corresponding to the induced MyAP ( iMyAP ) were found to be developmentally regulated in various vegetative organs .

Both young and old leaves exhibited wound-inducible iMyAP expression .

Furthermore , in the young plant , wounding resulted in a systemic increase in leaves located both acropetally and basipetally to the wounded leaf .

Also , the iMyAP transcripts were induced by methyl jasmonate , jasmonic acid and abscisic acid .

The different inductions could be antagonized by salicylic acid .

A general responsiveness in methyl-jasmonate-treated leaves was demonstrated by in situ hybridization .

No effect on the amount of iMyAP transcript was detected after feeding the plants with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid .

The similarity between MyAP and a lipase from Arabidopsis thaliana indicated a possible function in liberating acylated glucosinolates from their acyl group , thereby making them available for hydrolysis by the myrosinase enzymes .

We also report on a reduction in the amount of myrosinase transcripts derived from the vegetatively expressed MB-gene family after treatment with exogenously applied salicylic acid or abscisic acid .


Plants are the primary producers in most terrestrial ecosystems and have complex defense systems to protect their produce .

Defense-deficient , high-yielding agricultural monocultures attract abundant nonhuman consumers , but are alternatively defended through pesticide application and genetic engineering to produce insecticidal proteins such as Cry1Ac ( Bacillus thuringiensis ) .

These approaches alter the balance between yield protection and maximization but have been poorly contextualized to known yield-defense trade-offs in wild plants .

The native plant Nicotiana attenuata was used to compare yield benefits of plants transformed to be defenseless to those with a full suite of naturally evolved defenses , or additionally transformed to ectopically produce Cry1Ac .

An insecticide treatment allowed us to examine yield under different herbivore loads in N. attenuata 's native habitat .

Cry1Ac , herbivore damage , and growth parameters were monitored throughout the season .

Biomass and reproductive correlates were measured at season end .

Non-Cry1Ac-targeted herbivores dominated on noninsecticide-treated plants , and increased the yield drag of Cry1Ac-producing plants in comparison with endogenously defended or undefended plants .

Insecticide-sprayed Cry1Ac-producing plants lagged less in stalk height , shoot biomass , and flower production .

In direct comparison with the endogenous defenses of a native plant , Cry1Ac production did not provide yield benefits for plants under observed herbivore loads in a field study .


High temperature ( HT ) , high humidity ( HH ) , and pathogen infection often co-occur and negatively affect plant growth .

However , these stress factors and plant responses are generally studied in isolation .

The mechanisms of synergistic responses to combined stresses are poorly understood .

We isolated the subgroup IIb WRKY family member CaWRKY6 from Capsicum annuum and performed quantitative real-time PCR analysis .

CaWRKY6 expression was upregulated by individual or simultaneous treatment with HT , HH , combined HT and HH ( HTHH ) , and Ralstonia solanacearum inoculation , and responded to exogenous application of jasmonic acid ( JA ) , ethephon , and abscisic acid ( ABA ) .

Virus-induced gene silencing of CaWRKY6 enhanced pepper plant susceptibility to R. solanacearum and HTHH , and downregulated the hypersensitive response ( HR ) , JA- , ethylene (ET)- , and ABA-induced marker gene expression , and thermotolerance-associated expression of CaHSP24 , ER-small CaSHP , and Chl-small CaHSP .

CaWRKY6 overexpression in pepper attenuated the HTHH-induced suppression of resistance to R. solanacearum infection .

CaWRKY6 bound to and activated the CaWRKY40 promoter in planta , which is a pepper WRKY that regulates heat-stress tolerance and R. solanacearum resistance .

CaWRKY40 silencing significantly blocked HR-induced cell death and reduced transcriptional expression of CaWRKY40 .

These data suggest that CaWRKY6 is a positive regulator of R. solanacearum resistance and heat-stress tolerance , which occurs in part by activating CaWRKY40 .


Suspension cultures were incubated in the presence and absence of gibberellic acid ( GA(3 ) ) in an attempt to define a new experimental system for study of the molecular action of gibberellins upon growth .

Unlike many suspension cultures , an auxin-independent green clone from spinach ( Spinacia oleracea L. ) and an auxin-dependent line of " Paul 's Scarlet " rose ( Rosa sp. ) were promoted in expansion growth by GA(3 ) at 10(-11 ) to 10(-6 ) molar .

In Rosa the cells also elongated upon GA(3 ) treatment whereas in Spinacia they remained isodiametric .

Attempts were made to intensify the response .

The effect of GA(3 ) in Spinacia was stronger when gas exchange between the culture and the laboratory air was facilitated .

The response of Rosa was dependent on the presence of a cytokinin , although this culture did not require exogenous cytokinin for serial subculture .

GA(3 ) antagonized the growth retardant AMO-1618 in Rosa but not in Spinacia .

In general , conditions that enhanced growth also rendered GA(3 ) a more effective promoter ; conversely , GA(3 ) tended to become inhibitory under conditions that permitted only slow growth .


Phytohormones , such as salicylic acid ( SA ) , ethylene ( ET ) and jasmonic acid ( JA ) , play key roles in plant defence following pathogen attack .

The involvement of these hormones in susceptibility following Fusarium oxysporum ( Fo ) infection has mostly been studied in Arabidopsis thaliana .

However , Fo causes vascular wilt disease in a broad range of crops , including tomato ( Solanum lycopersicum ) .

Surprisingly little is known about the involvement of these phytohormones in the susceptibility of tomato towards Fo f. sp. lycopersici ( Fol ) .

Here , we investigate their involvement by the analysis of the expression of ET , JA and SA marker genes following Fol infection , and by bioassays of tomato mutants affected in either hormone production or perception .

Fol inoculation triggered the expression of SA and ET marker genes , showing the activation of these pathways .

NahG tomato , in which SA is degraded , became hypersusceptible to Fol infection and showed stronger disease symptoms than wild-type .

In contrast , ACD and Never ripe ( Nr ) mutants , in which ET biosynthesis and perception , respectively , are impaired , showed decreased disease symptoms and reduced fungal colonization on infection .

The susceptibility of the def1 tomato mutant , and a prosystemin over-expressing line , in which JA signalling is compromised or constitutively activated , respectively , was unaltered .

Our results show that SA is a negative and ET a positive regulator of Fol susceptibility .

The SA and ET signalling pathways appear to act synergistically , as an intact ET pathway is required for the induction of an SA marker gene , and vice versa .


Ca2 + and calmodulin ( CaM ) , a key Ca2 + sensor in all eukaryotes , have been implicated in defense responses in plants .

To elucidate the role of Ca2 + and CaM in defense signaling , we used 35S-labeled CaM to screen expression libraries prepared from tissues that were either treated with an elicitor derived from Phytophthora megasperma or infected with Pseudomonas syringae pv . tabaci .

Nineteen cDNAs that encode the same protein , pathogen-induced CaM-binding protein ( PICBP ) , were isolated .

The PICBP fusion proteins bound 35S-CaM , horseradish peroxidase-labeled CaM and CaM-Sepharose in the presence of Ca2 + whereas EGTA , a Ca2 + chelator , abolished binding , confirming that PICBP binds CaM in a Ca2 + -dependent manner .

Using a series of bacterially expressed truncated versions of PICBP , four CaM-binding domains , with a potential CaM-binding consensus sequence of WSNLKKVILLKRFVKSL , were identified .

The deduced PICBP protein sequence is rich in leucine residues and contains three classes of repeats .

The PICBP gene is differentially expressed in tissues with the highest expression in stem .

The expression of PICBP in Arabidopsis was induced in response to avirulent Pseudomonas syringae pv . tomato carrying avrRpm1 .

Furthermore , PICBP is constitutively expressed in the Arabidopsis accelerated cell death2 - 2 mutant .

The expression of PICBP in bean leaves was also induced after inoculation with avirulent and non-pathogenic bacterial strains .

In addition , the hrp1 mutant of Pseudomonas syringae pv . tabaci and inducers of plant defense such as salicylic acid , hydrogen peroxide and a fungal elicitor induced PICBP expression in bean .

Our data suggest a role for PICBP in Ca2 + -mediated defense signaling and cell-death .

Furthermore , PICBP is the first identified CBP in eukaryotes with four Ca2 + -dependent CaM-binding domains .


Allene oxide synthase ( AOS ) mediates the conversion of lipoxygenase-derived fatty acid hydroperoxides to unstable allene epoxides , which supply the precursors for the synthesis of the phytohormone jasmonic acid ( JA ) .

In this study the characterization of AOS gene expression in flax ( Linum usitatissimum ) is reported .

AOS was constitutively expressed in different organs of flax plants .

Additionally , AOS gene expression was enhanced after mechanical wounding in both the directly damaged leaves and in the systemic tissue located distal to the treated leaves .

This wound-induced accumulation of AOS required the de novo biosynthesis of other unknown proteins involved in the signaling pathway modulating wound-induced AOS gene expression .

Furthermore , the wound-induced AOS mRNA accumulation was correlated with the increase in the levels of JA .

Both JA and its precursor , 12-oxo-phytodienoic acid , activated AOS gene expression in a dose-dependent manner .

Thus , JA could activate its own biosynthetic pathway in flax leaves .

Moreover , neither salicylic acid ( SA ) nor aspirin influenced AOS enzymatic activity .

It is interesting that pretreatment with SA or aspirin inhibited wound-induced accumulation of AOS transcripts .

These results suggest that a potent inhibition of JA biosynthetic capacity in leaves can be affected by SA or aspirin at the level of AOS gene expression .


Recently , six genes of the gibberellin ( GA ) biosynthesis gene cluster in Gibberella fujikuroi were cloned and the functions of five of these genes were determined .

Here we describe the function of the sixth gene , P450 - 3 , and the cloning and functional analysis of a seventh gene , orf3 , located at the left border of the gene cluster .

We have thereby defined the complete GA biosynthesis gene cluster in this fungus .

The predicted amino acid sequence of orf3 revealed no close homology to known proteins .

High performance liquid chromatography and gas chromatography-mass spectrometry analyses of the culture fluid of knock-out mutants identified GA1 and GA4 , rather than GA3 and GA7 , as the major C19-GA products , suggesting that orf3 encodes the GA4 1,2-desaturase .

This was confirmed by transformation of the SG139 mutant , which lacks the GA biosynthesis gene cluster , with the desaturase gene renamed des .

The transformants converted GA4 to GA7 , and also metabolized GA9 ( 3-deoxyGA4 ) to GA120 ( 1,2-didehydroGA9 ) , but the 2alpha-hydroxylated compound GA40 was the major product in this case .

We demonstrate also by gene disruption that P450 - 3 , one of the four cytochrome P450 monooxygenase genes in the GA gene cluster , encodes the 13-hydroxylase , which catalyzes the conversion of GA7 to GA3 , in the last step of the pathway .

This enzyme also catalyzes the 13-hydroxylation of GA4 to GA1 .

Disruption of the des gene in an UV-induced P450 - 3 mutant produced a double mutant lacking both desaturase and 13-hydroxylase activities that accumulated high amounts of the commercially important GA4 .

The des and P450 - 3 genes differ in their regulation by nitrogen metabolite repression .

In common with the other five GA biosynthesis genes , expression of the desaturase gene is repressed by high amounts of nitrogen in the culture medium , whereas P450 - 3 is the only gene in the cluster not repressed by nitrogen .


In Nicotiana sylvestris , a set of nicotine biosynthesis genes were activated by exogenous application of methyl jasmonate , but the activation was effectively suppressed by simultaneous treatment with ethylene .

When N. sylvestris transgenic hairy roots were treated with a natural ethylene precursor , the jasmonate-responsive expression of the promoter from a nicotine pathway enzyme gene was completely suppressed , and this suppressive effect was abolished when ethylene perception was blocked with silver cation .

These and additional immunoblot results suggest that ethylene signal antagonizes jasmonate signal in nicotine biosynthesis .


Plant grafting is a sequential wound healing process .

However , whether wounding induces a different jasmonic acid ( JA ) response within half a day ( 12 h ) after grafting or non-grafting remains unclear .

Using the tomato hypocotyl grafting method , we show that grafting alleviates the asymmetrical accumulation of JA and jasmonic acid isoleucine conjugate ( JA-Ile ) in scion and rootstock caused by wounding , and from 2 h after tomato micrografting , grafting obviously restored the level of JA-Ile in the scion and rootstock .

Meanwhile , five JA-related genes , SlLOX11 , SlAOS , SlCOI1 , SlLAPA and SlJA2L , are detected and show significant changes in transcriptional expression patterns within 12 h of grafting , from asymmetrical to symmetrical , when the expression of 30 JA- and defense-related genes were analyzed .

The results indicated that grafting alleviates the asymmetrical JA and defense response between scion and rootstock of the tomato hypocotyl within 12 h as induced by wounding .

Moreover , we demonstrate that in the very early hours after grafting , JA-related genes may be involved in a molecular mechanism that changes asymmetrical expression as induced by wounding between scion and rootstock , thereby promoting wound healing and grafting success .


In order to characterize a specific extracellular 21-kDa calmodulin-binding protein ( named : ECBP21 ) from Angelica dahurica L. suspension-cultured cells , the cDNA coding for the protein has been cloned .

Here , Southern blot analysis shows that there are at least two copies of ECBP21 gene in Angelica genome .

Using truncated versions of ECBP21 and synthetic peptide in CaM binding assays , we mapped the calmodulin-binding domain to a 16-amino acid stretch ( residues 200 - 215 ) at the C-terminal region .

The ECBP21 was localized in the cell wall area by the immunogold electron microscopy and by GFP labeling method .

These results define ECBP21 as a kind of an extracellular calmodulin-binding protein ( CaMBP ) .

Furthermore , using Northern blot analysis , we examined the expression dynamics of ecbp21 during the incubation of Angelica suspension-cultured cells and the treatments with some growth regulators .

The above studies further provide the molecular evidence for the existence of the gene coding for extracellular CaMBPs and imply a possible role for ECBP21 .


The plant photoreceptor phytochrome is organised in a small gene family with phytochrome A ( phyA ) being unique , because it is specifically degraded upon activation by light .

This so called photodestruction is thought to be important for dynamic aspects of sensing such as measuring day length or shading by competitors .

Signal-triggered proteolytic degradation has emerged as central element of signal crosstalk in plants during recent years , but many of the molecular players are still unknown .

We therefore analyzed a jasmonate (JA)-deficient rice mutant , hebiba , that in several aspects resembles a mutant affected in photomorphogenesis .

In this mutant , the photodestruction of phyA is delayed as shown by in vivo spectroscopy and Western blot analysis .

Application of methyl-JA ( MeJA ) can rescue the delayed phyA photodestruction in the mutant in a time- and dose-dependent manner .

Light regulation of phyA transcripts thought to be under control of stable phytochrome B ( phyB ) is still functional .

The delayed photodestruction is accompanied by an elevated sensitivity of phytochrome-dependent growth responses to red and far-red light .


Health effects of subacute treatment of combinations of gibberellic acid and ethephon ( 2-chloroethylphosphonic acid ) were investigated .

Mice was used as an experimental model .

Ten groups of male ICR ( CD-1 ) mice were treated with oral doses of 25 , 50 and 100 mg of either gibberellic acid ( GA3 ) , ethephon ( 2-chloroethylphosphonic acid ) alone or in combination / kg body weight for 11 weeks .

A significant dose dependent reduction in weight gain and low dry matter intakes were recorded in animals treated with the combination of both chemicals .

Treated groups showed statistically significant increases in mean liver , kidney and spleen weights .

Hemoglobin ( Hb ) and total erythrocyte count ( TEC ) decreased while total leukocyte count ( TLC ) was raised in all treated groups .

Gibberellic acid ( alone ) treated animals showed the highest activity of liver aspartate aminotransferase ( AST ) while no significant variations were recorded among other groups .

No significant differences were recorded in the activity of hepatic alanine aminotransferase ( ALT ) .

A highly significant variation was recorded among the three treatments in serum urea level .

No significant difference was noted among the three treatments in serum creatinine .

All treatments caused significant dose dependent increases in creatinine than that of the control group .

A highly significant dose dependent variation occurred in acetyl choline esterase ( AChE ) activity among treated groups .

Groups treated with ethephon alone showed the greatest inhibition in brain AChE.


The behavior of naturally virulent Meloidogyne isolates toward the tomato resistance gene Mi in major tomato-growing areas in Israel was studied for the first time .

Virulence of seven selected isolates was confirmed over three successive generations on resistant ( Mi-carrying ) and susceptible ( non-Mi-carrying ) tomato cultivars .

Diagnostic markers verified the predominance of Meloidogyne javanica among virulent isolates selected on resistant tomato cultivars or rootstocks .

To better understand the determinants of nematode selection on Mi-carrying plants , reproduction of Mi-avirulent and virulent isolates Mjav1 and Mjv2 , respectively , measured as eggs per gram of root , on non-Mi-carrying , heterozygous ( Mi/mi ) and homozygous ( Mi/Mi ) genotypes was evaluated .

Although no reproduction of Mjav1 was observed on Mi/Mi genotypes , some reproduction was consistently observed on Mi/mi plants ; reproduction of Mjv2 on the homozygous and heterozygous genotypes was similar to that on susceptible cultivars , suggesting a limited quantitative effect of the Mi gene .

Histological examination of giant cells induced by Mi-virulent versus avirulent isolates confirmed the high virulence of Mjv2 on Mi/mi and Mi/Mi genotypes , allowing the formation of well-developed giant-cell systems despite the Mi gene .

Analysis of the plant defense response in tomato Mi/Mi , Mi/mi , and mi/mi genotypes to both avirulent and virulent isolates was investigated by quantitative real-time polymerase chain reaction .

Although the jasmonate (JA)-signaling pathway was clearly upregulated by avirulent and virulent isolates on the susceptible ( not carrying Mi ) and heterozygous ( Mi/mi ) plants , no change in signaling was observed in the homozygous ( Mi/Mi ) resistant line following incompatible interaction with the avirulent isolate .

Thus , similar to infection promoted by the avirulent isolate on the susceptible genotype , the Mi-virulent isolate induced the JA-dependent pathway , which might promote tomato susceptibility during the compatible interaction with the homozygous ( Mi/Mi ) resistant line .

These results have important consequences for the management of Mi resistance genes for ensuring sustainable tomato farming .


Petal color , size , and morphology play important roles in protecting other floral organs , attracting pollinators , and facilitating sexual reproduction in plants .

In a previous study , we obtained a petal degeneration mutant ( pdm ) from the ' FT ' doubled haploid line of Chinese cabbage and found that the candidate gene for pdm , Bra040093 , encodes the enzyme acyl-CoA oxidase1 .

In this study , we sought to examine the gene networks regulating petal development in pdm plants .

We show that the mRNA and protein expression of Bra040093 , which is involved in the jasmonic acid ( JA ) biosynthetic pathway , were significantly lower in the petals of pdm plants than in those of ' FT ' plants .

Similarly , the JA and methyl jasmonate ( MeJA ) contents of petals were significantly lower in pdm plants than in ' FT ' plants and we found that exogenous application of these hormones to the inflorescences of pdm plants restored the ' FT ' phenotype .

Comparative analyses of the transcriptomes of ' FT ' , pdm and pdm + JA ( pJA ) plants revealed 10,160 differentially expressed genes ( DEGs ) with consistent expression tendencies in ' FT ' vs. pdm and pJA vs. pdm comparisons .

Among these DEGs , we identified 69 DEGs related to floral organ development , 11 of which are involved in petal development regulated by JA .

On the basis of qRT-PCR verification , we propose regulatory pathways whereby JA may mediate petal development in the pdm mutant .

We demonstrate that mutation of Bra040093 in pdm plants leads to reduced JA levels and that this in turn promotes changes in the expression of genes that are expressed in response to JA , ultimately resulting in petal degeneration .

These findings thus indicate that JA is associated with petal development in Chinese cabbage .

These results enhance our knowledge on the molecular mechanisms underlying petal development and lay the foundations for further elucidation of the mechanisms associated with floral organ development in Chinese cabbage .


In Arabidopsis , the flagellin-derived peptide flg22 elevates antibacterial resistance [ 1 ] and inhibits growth [ 2 ] upon perception via the leucine-rich repeat receptor-like kinase Flagellin-Sensitive 2 ( FLS2 ) [ 3 ] .

DELLA proteins are plant growth repressors whose degradation is promoted by the phytohormone gibberellin [ 4 ] .

Here , we show that DELLA stabilization contributes to flg22-induced growth inhibition .

In addition , we show that DELLAs promote susceptibility to virulent biotrophs and resistance to necrotrophs , partly by altering the relative strength of salicylic acid and jasmonic acid ( JA ) signaling .

A quadruple-DELLA mutant ( which lacks four out of the five Arabidopsis DELLA proteins [ 5 ] ) was partially insensitive to gene induction by Methyl-Jasmonate ( MeJA ) , whereas the constitutively active dominant DELLA mutant gai[6 ] was sensitized for JA-responsive gene induction , implicating DELLAs in JA-signaling and/or perception .

Accordingly , the elevated resistance of gai to the necrotrophic fungus Alternaria brassicicola and susceptibility to the hemibiotroph Pseudomonas syringae pv . tomato strain DC3000 ( Pto DC3000 ) was attenuated in the JA-insensitive coi1 - 16 mutant [ 7 ] .

These findings suggest an explanation for why the necrotrophic fungus Gibberella fujikuroi , causal agent of the foolish-seedling disease of rice , makes gibberellin .


An important question is what genes govern the differentiation of plant embryos into suspensor and embryo proper regions following fertilization and division of the zygote .

We compared embryo proper and suspensor transcriptomes of four plants that vary in embryo morphology within the suspensor region .

We determined that genes encoding enzymes in several metabolic pathways leading to the formation of hormones , such as gibberellic acid , and other metabolites are up-regulated in giant scarlet runner bean and common bean suspensors .

Genes involved in transport and Golgi body organization are up-regulated within the suspensors of these plants as well , strengthening the view that giant specialized suspensors serve as a hormone factory and a conduit for transferring substances to the developing embryo proper .

By contrast , genes controlling transcriptional regulation , development , and cell division are up-regulated primarily within the embryo proper .

Transcriptomes from less specialized soybean and Arabidopsis suspensors demonstrated that fewer genes encoding metabolic enzymes and hormones are up-regulated .

Genes active in the embryo proper , however , are functionally similar to those active in scarlet runner bean and common bean embryo proper regions .

We uncovered a set of suspensor- and embryo proper-specific transcription factors ( TFs ) that are shared by all embryos irrespective of morphology , suggesting that they are involved in early differentiation processes common to all plants .

Chromatin immunoprecipitation sequencing ( ChIP-Seq ) experiments with scarlet runner bean and soybean WOX9 , an up-regulated suspensor TF , gained entry into a regulatory network important for suspensor development irrespective of morphology .


The goal of this study was to determine whether the application of gibberellic acid ( GA(3 ) ) to seeds of common wheat varieties with different vernalization and photoperiod requirements affects the transition from vegetative to generative stage .

Three varieties of wheat with different photoperiod sensitivities and vernalization were selected for the experiment-the winter varieties , Mironovskaya and Bezostaya , and the spring variety , Sirael . Seeds were treated with different concentrations of GA(3 ) and plants were grown under long-day conditions with monitoring of their photosynthetic activity ( F(v)/F(m ) , P(n ) , E , g(s ) ) .

We monitored the activity of the photosynthetic apparatus by checking the plants to see if they were growing properly .

The phenological stages of the wheat species were checked for indications of a transition from the vegetative to the generative stage .

Selected concentrations of GA(3 ) had no effect on the compensation of the vernalization process ( transition to the generative phase ) .

Chlorophyll fluorescence was one of the factors for monitoring stress .

The variety , Bezostaya , is similar to the spring variety , Sirael , in its trends and values .

The growth conditions of Bezostaya and Sirael were not affected by the activity of the photosynthetic apparatus .

The development of growing points in winter varieties occurred at the prolonged single ridge stage .

The spring variety reached the stage of head emergence after sixty days of growth ( changes to the flowering phase did not appear in winter wheat ) .

Application of GA(3 ) to the seeds had no effect on the transition of the growing point to the double-ridge generative stage .

The present study highlights the priming effect of GA(3 ) on seeds of common wheat varieties with different vernalization and photoperiod requirements as it affected the transition from vegetative to generative stage .


The phloem plays a crucial role in assimilate and nutrient transport , pathogen response , and plant growth and development .

Yet , few species have yielded pure phloem exudate and , if proteins need to be analysed , those species may not have sequenced genomes , making identification difficult .

The enrichment of Arabidopsis thaliana phloem exudate in amounts large enough to allow for metabolite and protein analysis is described .

Using this method , it was possible to identify 65 proteins present in the Arabidopsis phloem exudate .

The majority of these proteins could be grouped by response to pathogens , stress , or hormones , carbon metabolism , protein interaction , modification , and turnover , and transcription factors .

Along with putative lipid-binding proteins , several lipids and fatty acids could be identified .

Only a few examples exist of lipids ( jasmonic acid , oxylipins ) or lipid-binding proteins ( DIR1 , acyl-CoA-binding protein ) in the phloem .

Finding hydrophobic compounds in an aqueous environment is not without precedence in biological systems : human blood contains a variety of lipids , many of which play a significant role in human health .

In blood , lipids are transported while bound to proteins .

The present findings of lipids and lipid-binding proteins in phloem exudates suggest that a similar long-distance lipid signalling exists in plants and may play an important role in plant growth and development .


Abscisic acid ( ABA ) inhibits the production of ethylene induced by water stress in excised wheat leaves and counteracts the stimulatory effect of 6-benzyladenine ( BA ) on this process .

The stimulatory effect of BA and the inhibitory effect of ABA were equally pronounced whether external or endogenous ethylene levels were determined .

When leaves were sprayed or floated on solutions of BA , indole-3-acetic acid ( IAA ) , gibberellic acid ( GA3 ) , or ABA , the relative activities of these growth regulators on stress-induced ethylene at 10(-4 ) mol l(-1 ) were BA > IAA > GA3>controls > ABA .

In non-stressed leaves , however , where the levels of ethylene produced were 2 - 20 times smaller , the relative activities were IAA > BA > GA3>controls > ABA .

The effects of BA and ABA spray treatment on water stress induced ethylene were closely similar whether the solutions were applied 2 or 18 h prior to the initiation of water stress .

The relationships between the levels of endogenous growth regulators in the plant and ethylene release induced by water stress are discussed .


Two-week-old dwarf peas ( Pisum sativum cv Little Marvel ) were sprayed with gibberellic acid ( GA(3 ) ) , and after 3 or 4 days the upper stem and young leaf samples were analyzed for indole-3-acetic acid ( IAA ) and indole-3-acetyl aspartic acid by an isotope dilution high performance liquid chromatography method .

GA(3 ) increased IAA levels as much as 8-fold and decreased indole-3-acetyl aspartic acid levels .


BACKGROUND : Rare data are available on the molecular responses of higher plants to low pH. Seedlings of ' Sour pummelo ' ( Citrus grandis ) and ' Xuegan ' ( Citrus sinensis ) were treated daily with nutrient solution at a pH of 2.5 , 3 , or 6 ( control ) for nine months .

Thereafter , we first used 2-dimensional electrophoresis ( 2-DE ) to investigate low pH-responsive proteins in Citrus leaves .

Meanwhile , we examined low pH-effects on leaf gas exchange , carbohydrates , ascorbate , dehydroascorbate and malondialdehyde .

The objectives were to understand the adaptive mechanisms of Citrus to low pH and to identify the possible candidate proteins for low pH-tolerance .

RESULTS : Our results demonstrated that Citrus were tolerant to low pH , with a slightly higher low pH-tolerance in the C. sinensis than in the C. grandis .

Using 2-DE , we identified more pH 2.5-responsive proteins than pH 3-responsive proteins in leaves .

This paper discussed mainly on the pH 2.5-responsive proteins .

pH 2.5 decreased the abundances of proteins involved in ribulose bisphosphate carboxylase/oxygenase activation , Calvin cycle , carbon fixation , chlorophyll biosynthesis and electron transport , hence lowering chlorophyll level , electron transport rate and photosynthesis .

The higher oxidative damage in the pH 2.5-treated C. grandis leaves might be due to a combination of factors including higher production of reactive oxygen species , more proteins decreased in abundance involved in antioxidation and detoxification , and lower ascorbate level .

Protein and amino acid metabolisms were less affected in the C. sinensis leaves than those in the C. grandis leaves when exposed to pH 2.5 .

The abundances of proteins related to jasmonic acid biosynthesis and signal transduction were increased and decreased in the pH 2.5-treated C. sinensis and C. grandis leaves , respectively .

CONCLUSIONS : This is the first report on low pH-responsive proteins in higher plants .

Thus , our results provide some novel information on low pH-toxicity and -tolerance in higher plants .


Plastids are the central orchestrators of the early and late responses to wounding and herbivory in plants .

This organelle houses some of the most important enzymes involved in the biogenesis of intra and extracellular signals that mediate defense responses against these stresses .

Among these enzymes are the ones initiating the biosynthesis of oxylipins [ e.g. , jasmonic acid ( JA ) and C(6 ) volatiles ] , terpenoid volatiles and phenolic compounds , including both volatile [ e.g. , methylsalicylate ( MeSA ) ] and non-volatile compounds [ e.g. , salicylic acid ( SA ) ] .

Plastids also play a major role in orchestrating changes in primary metabolism during herbivory and thereby in the reallocation of carbon and nitrogen to different functions in response to herbivory .

How the primary stress signals generated by mechanical damage and herbivory reach the plastid to activate the rapid synthesis of these signal molecules is at present largely unknown .


Gibberellic acid ( GA ) regulates many aspects of plant growth and development .

The DELLA proteins act to restrain plant growth , and GA relieves this repression by promoting their degradation via the 26S proteasome pathway .

The elucidation of the crystalline structure of the GA soluble receptor GID1 protein represents an important breakthrough for understanding the way in which GA is perceived and how it induces the destabilization of the DELLA proteins .

Recent advances have revealed that the DELLA proteins are involved in protein-protein interactions within various environmental and hormone signaling pathways .

In this review , we highlight our current understanding of the ' relief of repression ' model that aims to explain the role of GA and the function of the DELLA proteins , incorporating the many aspects of cross-talk shown to exist in the control of plant development and the response to stress .


Herbivore attacks induce leaves to emit a specific blend of volatiles .

Here we show that exposure to Tetranychus urticae-induced volatiles , as well as T. urticae infestation and artificial wounding , activates the transcription of the genes involved in the biosynthesis of ethylene [ S-adenosylmethionine ( SAM ) synthetase and 1-aminocyclopropane-1-carboxylic acid oxidase ] and a gene involved in the biosynthesis of polyamines from SAM ( SAM decarboxylase ) in lima bean leaves .

Moreover , exposure of leaves to any one of the seven major chemical components of T. urticae-induced volatiles also induces expression of these genes .

Furthermore , we found that , when lima bean plants were exposed to T. urticae-induced volatiles , they emitted ethylene .

Lima bean plants infested by T. urticae and artificially wounded plants also emitted ethylene .

Endogenous polyamine levels were not increased in the exposed leaves or the infested leaves , suggesting that polyamine production from SAM was only slightly promoted at the metabolic levels present in the leaves .

We found that jasmonate ( JA ) accumulated in leaves exposed to T. urticae-induced volatiles , and that both JA and salicylate ( SA ) accumulated in leaves infested by T. urticae .

These findings , as well as results of pharmacological analyses , suggest that , in leaves exposed to T. urticae-induced volatiles , ethylene biosynthesis might be regulated by pathways involving JA and the ethylene positive feedback loop .

They also suggest that ethylene biosynthesis might be regulated by signaling pathways involving JA , SA and ethylene in T. urticae-infested leaves .


Precise floral transition from vegetative growth phase to reproductive growth phase is very important in plant life cycle .

In flowering genetic pathways , DELLA proteins are master transcriptional regulators of gibberelic acid ( GA ) pathway , and FLOWERING LOCUS C ( FLC ) is a core repressor of vernalization pathway as well as downstream of DELLAs .

As a crucial messenger in plants , the possible involvement of melatonin ( N-acetyl-5-methoxytryptamine ) in flowering and underlying molecular mechanism are unknown in Arabidopsis .

In this study , we found that exogenous melatonin treatment delayed floral transition in Arabidopsis .

Exogenous melatonin treatment conferred protein stabilizations of DELLAs [ REPRESSOR of ga1 - 3 ( RGA ) and RGA-LIKE3 ( RGL3 ) ] , without regulating the transcripts of DELLAs and endogenous GA level .

Notably , exogenous melatonin delayed plant flowering and DELLA-activated transcripts of FLC were alleviated in della mutants , and those were exacerbated in DELLA overexpressing plants .

Taken together , this study provides direct link between melatonin and floral transition , and indicates the novel involvement of DELLAs-activated FLC in melatonin-mediated flowering in Arabidopsis .


Glomus mosseae , a representative species of Endogonaceae ( Phycomycetes ) able to form vesicular-arbuscular mycorrhiza , was investigated for phytohormone production .

Spores of G. mosseae were axenically germinated in water , and the resultant mycelial growth was assayed by standard procedures for extracting plant hormones from microbial cultures .

Paper partition chromatography and specific bioassays were used to separate and identify plant growth-regulating substances .

The microorganism synthesized at least two gibberellin-like substances , one with R(f ) corresponding in position to authentic gibberellic acid , and four substances with the properties of cytokinins .


Jasmonates control defense gene expression and male fertility in the model plant Arabidopsis thaliana .

In both cases , the involvement of the jasmonate pathway is complex , involving large-scale transcriptional reprogramming .

Additionally , jasmonate signaling is hard-wired into the auxin , ethylene , and salicylate signal networks , all of which are under intense investigation in Arabidopsis .

In male fertility , jasmonic acid ( JA ) is the essential signal intervening both at the level of anther elongation and in pollen dehiscense .

A number of genes potentially involved in jasmonate-dependent anther elongation have recently been discovered .

In the case of defense , at least two jasmonates , JA and its precursor 12-oxo-phytodienoic acid ( OPDA ) , are necessary for the fine-tuning of defense gene expression in response to various microbial pathogens and arthropod herbivores .

However , only OPDA is required for full resistance to some insects and fungi .

Other jasmonates probably affect yet more physiological responses .

A series of breakthroughs have identified the SKP/CULLIN/F-BOX ( SCF ) , CORONATINE INSENSITIVE ( COI1 ) complex , acting together with the CONSTITUTIVE PHOTOMORPHOGENIC 9 ( COP9 ) signalosome , as central regulatory components of jasmonate signaling in Arabidopsis .

The studies , mostly involving mutational approaches , have paved the way for suppressor screens that are expected to further extend our knowledge of jasmonate signaling .

When these and other new mutants affecting jasmonate signaling are characterized , new nodes will be added to the Arabidopsis Jasmonate Signaling Pathway Connections Map , and the lists of target genes regulated by jasmonates in Arabidopsis will be expanded .


Bowman-Birk inhibitor ( BBI ) genes encode serine protease inhibitors well known for their anticarcinogenic properties and roles in plant defense against insects and pathogens .

Here we investigated the expression of a BBI gene in response to water deficit , recovery and phytohormones .

A full length cDNA encoding a novel BBI ( AhBBI ) was isolated from peanut ( Arachis hypogaea L. ) leaves .

The deduced protein is a polypeptide of 11.5kDa containing a signal peptide of 20 amino acids which is missing from peanut seed full-length BBI .

Sequence analysis showed that AhBBI presents the characteristic features of BBIs but its first inhibitory loop is unique among the Fabaceae species .

Real-time PCR analyses indicated that in peanut leaves , AhBBI is upregulated by water deficit and exogenous jasmonic acid ( JA ) but repressed by abscissic acid ( ABA ) after 24h of treatment .

The transcripts accumulation patterns during water deficit differed between two cultivars studied in relation to their tolerance levels to drought .

AhBBI transcripts accumulated earlier and stronger in the tolerant cultivar ( cv . Fleur11 ) compared to the susceptible one ( cv . 73 - 30 ) suggesting that BBI genes are involved in drought stress tolerance .

Subsequent rehydration reversed the accumulation of AhBBI transcripts in both cultivars but at different levels .

The overall role of BBI in abiotic stress tolerance and the possible mechanisms of action are discussed .


Biotic and abiotic stress induces the formation of galactolipids esterified with the phytohormones 12-oxo-phytodienoic acid ( OPDA ) and dinor-oxo-phytodienoic acid ( dnOPDA ) in Arabidopsis thaliana .

The biosynthetic pathways of free (dn)OPDA is well described , but it is unclear how they are incorporated into galactolipids .

We herein show that (dn)OPDA containing lipids are formed rapidly after disruption of cellular integrity in leaf tissue .

Five minutes after freeze-thawing , 60 - 70 % of the trienoic acids esterified to chloroplast galactolipids are converted to (dn)OPDA .

Stable isotope labeling with (18)O-water provides strong evidence for that the fatty acids remain attached to galactolipids during the enzymatic conversion to (dn)OPDA .


Plants respond to stresses by producing a broad spectrum of bioactive specialized metabolites .

Hormonal elicitors , such as jasmonates , trigger a complex signaling circuit leading to the concerted activation of specific metabolic pathways .

However , for many specialized metabolic pathways , the transcription factors involved remain unknown .

Here , we report on two homologous jasmonate-inducible transcription factors of the basic helix-loop-helix family , TRITERPENE SAPONIN BIOSYNTHESIS ACTIVATING REGULATOR1 ( TSAR1 ) and TSAR2 , which direct triterpene saponin biosynthesis in Medicago truncatula .

TSAR1 and TSAR2 are coregulated with and transactivate the genes encoding 3-HYDROXY-3-METHYLGLUTARYL-COENZYME A REDUCTASE1 ( HMGR1 ) and MAKIBISHI1 , the rate-limiting enzyme for triterpene biosynthesis and an E3 ubiquitin ligase that controls HMGR1 levels , respectively .

Transactivation is mediated by direct binding of TSARs to the N-box in the promoter of HMGR1 .

In transient expression assays in tobacco ( Nicotiana tabacum ) protoplasts , TSAR1 and TSAR2 exhibit different patterns of transactivation of downstream triterpene saponin biosynthetic genes , hinting at distinct functionalities within the regulation of the pathway .

Correspondingly , overexpression of TSAR1 or TSAR2 in M. truncatula hairy roots resulted in elevated transcript levels of known triterpene saponin biosynthetic genes and strongly increased the accumulation of triterpene saponins .

TSAR2 overexpression specifically boosted hemolytic saponin biosynthesis , whereas TSAR1 overexpression primarily stimulated nonhemolytic soyasaponin biosynthesis .

Both TSARs also activated all genes of the precursor mevalonate pathway but did not affect sterol biosynthetic genes , pointing to their specific role as regulators of specialized triterpene metabolism in M. truncatula .


The hormone jasmonate ( JA ) , which functions in plant immunity , regulates resistance to pathogen infection and insect attack through triggering genome-wide transcriptional reprogramming in plants .

We show that the basic helix-loop-helix transcription factor ( TF ) MYC2 in tomato ( Solanum lycopersicum ) acts downstream of the JA receptor to orchestrate JA-mediated activation of both the wounding and pathogen responses .

Using chromatin immunoprecipitation sequencing ( ChIP-seq ) coupled with RNA sequencing ( RNA-seq ) assays , we identified 655 MYC2-targeted JA-responsive genes .

These genes are highly enriched in Gene Ontology categories related to TFs and the early response to JA , indicating that MYC2 functions at a high hierarchical level to regulate JA-mediated gene transcription .

We also identified a group of MYC2-targeted TFs ( MTFs ) that may directly regulate the JA-induced transcription of late defense genes .

Our findings suggest that MYC2 and its downstream MTFs form a hierarchical transcriptional cascade during JA-mediated plant immunity that initiates and amplifies transcriptional output .

As proof of concept , we showed that during plant resistance to the necrotrophic pathogen Botrytis cinerea , MYC2 and the MTF JA2-Like form a transcription module that preferentially regulates wounding-responsive genes , whereas MYC2 and the MTF ETHYLENE RESPONSE FACTOR.C3 form a transcription module that preferentially regulates pathogen-responsive genes .


Plants sense and respond to microbes utilizing a multilayered signalling cascade .

In seed plants , the phytohormones jasmonic and salicylic acid ( JA and SA ) are key denominators of how plants respond to certain microbes .

Their interplay is especially well-known for tipping the scales in plants ' strategies of dealing with phytopathogens .

In non-angiosperm lineages , the interplay is less well understood , but current data indicate that it is intertwined to a lesser extent and the canonical JA/SA antagonism appears to be absent .

Here , we used the water fern Azolla filiculoides to gain insights into the fern 's JA/SA signalling and the molecular communication with its unique nitrogen fixing cyanobiont Nostoc azollae , which the fern inherits both during sexual and vegetative reproduction .

By mining large-scale sequencing data , we demonstrate that Azolla has most of the genetic repertoire to produce and sense JA and SA .

Using qRT-PCR on the identified biosynthesis and signalling marker genes , we show that Azolla is responsive to exogenously applied SA .

Furthermore , exogenous SA application influenced the abundance and gene expression of Azolla 's cyanobiont .

Our data provide a framework for JA/SA signalling in ferns and suggest that SA might be involved in Azolla 's communication with its vertically inherited cyanobiont .


The induction of alpha-amylase triggered by gibberellic acid in barley embryos is repressed by sugars .

We investigated the effects of glucose on the gibberellin signal transduction pathway to localize the site of interaction of the sugar/hormone signalling pathways .

Our results indicate that glucose represses gibberellin signalling late along this hormone transduction pathway , downstream of transcription of the gibberellin-modulated transcriptional activator ( GAMYB ) needed for alpha-amylase induction .

This result suggests either that glucose repression is transduced by a pathway independent of gibberellin signalling or that repression occurs at the level of GAMYB translation .


Callus cells of Daucus carota L. have different phenylpropanoid pathways depending on the medium composition .

Cells propagated on a medium with gibberellic acid do not accumulate cyanidin but incorporate [(14)C]phenylalanine into chlorogenic acid at a high rate .

Cells grown on a medium free of gibberellic acid accumulate cyanidin in very large amounts .

We here describe partial purification of hydroxycinnamate : CoA ligase , and its properties in these two cell lines .

The enzymes extracted from the two cell populations had different substrate specifities : for that from anthocyanin-containing cells , p-coumaric acid was the best substrate , and caffeic acid and ferulic acid were also activated .

With enzyme from anthocyanin-free cells , the lowest Km values were obtained for caffeic acid , while ferulic acid had higher values , and p-coumaric acid was nearly inactive .

The enzyme did not separate into isoenzymes during purification .

Only on polyacrylamide gels the partially purified enzyme from anthocyanin-containing cells separated into three peaks , and that from anthocyanin-free cells , into only two peaks .

This difference is discussed in the context of the lack of activity with p-coumaric acid in anthocyanin-free cells .


We analyzed expression of marker genes for three defense pathways during infection by Cauliflower mosaic virus ( CaMV ) , a compatible pathogen of Arabidopsis ( Arabidopsis thaliana ) , using luciferase reporter transgenes and directly by measuring transcript abundance .

Expression of PR-1 , a marker for salicylic acid signaling , was very low until 8 d postinoculation and then rose sharply , coinciding with the rise in virus levels .

In contrast , as early as 2 h postinoculation , transcriptional up-regulation of GST1-a marker for reactive oxygen species-and PDF1.2-a marker for jasmonic acid/ethylene defense signaling-was detectable in the virus-inoculated leaf and systemically . In parallel with the activation of GST1 , H(2)O(2 ) accumulated locally and systemically in virus- but not mock-inoculated plants .

However , in plants inoculated with infectious CaMV DNA rather than virus particles , the onset of systemic luciferase activity was delayed by 24 to 48 h , suggesting that virion structural proteins act as the elicitor .

This phenomenon , which we term the rapid systemic response , preceded virus movement from the inoculated leaf ; therefore , the systemic signal is not viral .

Systemic , but not local , H(2)O(2 ) accumulation was abolished in rbohDF double mutants and in etr1 - 1 and ein2 - 1 mutants , implicating NADPH oxidase and ethylene signaling in the generation and transduction of the response .

Ethylene , but not rbohDF mutants , also showed reduced susceptibility to CaMV , whereas in NahG transgenics , virus levels were similar to wild type .

These findings implicate reactive oxygen species and ethylene in signaling in response to CaMV infection , but suggest that salicylic acid does not play an effective role .


Proteomic approaches using two-dimensional gel electrophoresis ( 2-DE ) were adopted to identify proteins from rice leaf that are differentially expressed in response to the rice blast fungus , Magnaporthe grisea .

Microscopic observation of inoculated leaf with M. grisea revealed that callose deposition and hypersensitive response was clearly visible in incompatible interactions but excessive invading hypha with branches were evident in compatible interactions .

Proteins were extracted from leaves 24 , 48 , and 72 hours after rice blast fungus inoculation .

Eight proteins resolved on the 2-DE gels were induced or increased in the inoculated leaf .

Matrix-assisted laser desorption/ionization-time of flight analysis of these differentially displayed proteins showed them to be two receptor-like protein kinases ( RLK ) , two beta-1.3-glucanases ( Glu1 , Glu2 ) , thaumatin-like protein ( TLP ) , peroxidase ( POX 22.3 ) , probenazole-inducible protein ( PBZ1 ) , and rice pathogenesis-related 10 ( OsPR-10 ) .

Of these proteins , RLK , TLP , PBZ , and OsPR-10 proteins were induced more in the incompatible interactions than in compatible ones .

A phytohormone , jasmonic acid also induced all eight proteins in leaves .

To confirm whether the expression profile is equal to the 2-DE data , seven cDNA clones were used as probes in Northern hybridization experiments using total RNA from leaf tissues inoculated with incompatible and compatible rice blast fungal races .

The genes encoding POX22.3 , Glu1 , Glu2 , TLP , OsRLK , PBZ1 , and OsPR-10 were activated in inoculated leaves , with TLP , OsRLK , PBZ1 , and OsPR-10 being expressed earlier and more in incompatible than in compatible interactions .

These results suggest that early and high induction of these genes may provide host plants with leading edges to defend themselves .

The localization of two rice PR-10 proteins , PBZ1 and OsPR-10 , was further examined by immunohistochemical analysis .

PBZ1 accumulated highly in mesophyll cells under the attachment site of the appressorium .

In contrast , OsPR-10 expression was mainly localized to vascular tissue .


Agricultural practices in grapevines management include water restrictions due to its positive effect on wine quality , especially when applied at fruit ripening .

Although the effects of water stress in some groups of phytohormones have already been described in leaves and whole grapes , information regarding tissue-specific variations in hormones during ripening in grapes is scarce .

Field-grown grapevines from the cv . " Merlot " were subjected to two differential water supplies , including only rainfed , non-irrigated vines ( T0 ) and vines additionally irrigated with 25Lweek(-1 ) vine(-1 ) ( T1 ) .

Tissue-specific variations in the hormonal profiling of grapes [ including changes in the contents of abscisic acid ( ABA ) , jasmonic acid ( JA ) , salicylic acid ( SA ) , the ethylene precursor 1-amino-cyclopropane-1-carboxylic acid ( ACC ) , the auxin indole-3-acetic acid , gibberellins 1 , 3 , 4 , and 7 ( GA(1 ) , GA(3 ) , GA(4 ) , and GA(7 ) ) , the cytokinins trans-zeatin , and 2-isopentenyl adenine , including as well their respective ribosylated forms ] were periodically evaluated from veraison to harvest .

The hormonal profiling in leaves was also measured at the beginning and end of the season for comparison .

Results showed that grape growth dynamics were transiently affected by the differences in water regimes , the increased water supply leading to an accelerated growth , slightly reduced accumulation of sugars , and transiently lowered pH , although grape quality did not differ between treatments at harvest .

Hormonal profiling of whole berries did not reveal any difference in the endogenous contents of phytohormones between treatments , except for a transient decrease in GA(4 ) contents in T1 compared to T0 vines , which was not confirmed at the tissular level .

Hormonal profiling at the tissue level highlighted a differential accumulation of phytohormones during ripening in berry tissues , with pulps being particularly poor in ABA , JA , and SA contents , seeds particularly accumulating ACC , gibberellins , and zeatin-type cytokinins , and the skin being particularly rich in auxin and active cytokinins .

Changes in water supply led to very small and transient changes in the endogenous contents of phytohormones in the seeds , pulp , and skin of berries , the most remarkable variations being observed in cytokinin contents , which increased earlier [ between 5 and 12days after veraison ( DAV ) ] but later kept more constant in the skin from T1 compared to T0 vines and were also 3-fold higher at 40 DAV in seeds of T1 compared to T0 vines .

It is concluded that small changes in water supply can trigger hormonal-driven physiological adjustments at the tissular level affecting the evolution of fruit growth and quality throughout grape berry ripening .


Seed dormancy and germination in higher plants are partially controlled by the plant hormones abscisic acid ( ABA ) and gibberellic acid ( GA ) .

ABA establishes dormancy during embryo maturation , whereas GA breaks dormancy and induces germination .

Previous attempts to identify GA response genes were confounded because GA mutants are not expected to germinate and , unlike GA auxotrophs , should fail to be rescued by exogenous GA .

Here , we describe a screen for suppressors of the ABA-insensitive mutant ABI1 - 1 that enriches for GA auxotrophs and GA-insensitive mutants .

The vast majority ( 76 % ) of the suppressors of ABI1 - 1 strongly resemble GA auxotrophs in that they are severely dwarfed and have dark green foliage and flowers with underdeveloped petals and stamen .

Three isolates were alleles of the GA auxotroph ga1 .

The remaining severe dwarves were not rescued by GA and belong to a single complementation group that we designate sly1 ( Sleepy 1 ) .

The alleles of sly1 identified are the first recessive GA-insensitive mutations to reflect the full spectrum of GA-associated phenotypes , including the failure to germinate in the absence of the ABI1 - 1 lesion .

Thus , we postulate that SLY1 is a key factor in GA reception .


Brassinosteroids ( BRs ) and jasmonates ( JAs ) regulate plant growth , development , and defense responses , but how these phytohormones mediate the growth-defense tradeoff is unclear .

Here , we identified the Arabidopsis ( Arabidopsis thaliana ) dwarf at early stages1 ( dwe1 ) mutant , which exhibits enhanced expression of defensin genes PLANT DEFENSIN1.2a ( PDF1.2a ) and PDF1.2b The dwe1 mutant showed increased resistance to herbivory by beet armyworms ( Spodoptera exigua ) and infection by botrytis ( Botrytis cinerea ) .

DWE1 encodes ROTUNDIFOLIA3 , a cytochrome P450 protein essential for BR biosynthesis .

The JA-inducible transcription of PDF1.2a and PDF1.2b was significantly reduced in the BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1 ( BES1 ) gain-of-function mutant bes1- D , which was highly susceptible to S. exigua and B. cinerea BES1 directly targeted the terminator regions of PDF1.2a/PDF1.2b and suppressed their expression .

PDF1.2a overexpression diminished the enhanced susceptibility of bes1- D to B. cinerea but did not improve resistance of bes1- D to S. exigua In response to S. exigua herbivory , BES1 inhibited biosynthesis of the JA-induced insect defense-related metabolite indolic glucosinolate by interacting with transcription factors MYB DOMAIN PROTEIN34 ( MYB34 ) , MYB51 , and MYB122 and suppressing expression of genes encoding CYTOCHROME P450 FAMILY79 SUBFAMILY B POLYPEPTIDE3 ( CYP79B3 ) and UDP-GLUCOSYL TRANSFERASE 74B1 ( UGT74B1 ) .

Thus , BR contributes to the growth-defense tradeoff by suppressing expression of defensin and glucosinolate biosynthesis genes .


Jasmonates ( JAs ) are well-known regulators of stress , defence , and secondary metabolism in plants , with JA perception triggering extensive transcriptional reprogramming , including both activation and/or repression of entire metabolic pathways .

We performed RNA sequencing based transcriptomic profiling of tobacco BY-2 cells before and after treatment with methyl jasmonate ( MeJA ) to identify novel transcriptional regulators associated with alkaloid formation .

A total of 107,140 unigenes were obtained through de novo assembly , and at least 33,213 transcripts ( 31 % ) encode proteins , in which 3419 transcription factors ( TFs ) were identified , representing 72 gene families , as well as 840 transcriptional regulators ( TRs ) distributed among 19 gene families .

After MeJA treatment BY-2 cells , 7260 differentially expressed transcripts were characterised , which include 4443 MeJA-upregulated and 2817 MeJA-downregulated genes .

Of these , 227 TFs/TRs in 36 families were specifically upregulated , and 102 TFs/TRs in 38 families were downregulated in MeJA-treated BY-2 cells .

We further showed that the expression of 12 ethylene response factors and four basic helix-loop-helix factors increased at the transcriptional level after MeJA treatment in BY-2 cells and displayed specific expression patterns in nic mutants with or without MeJA treatments .

Our data provide a catalogue of transcripts of tobacco BY-2 cells and benefit future study of JA-modulated regulation of secondary metabolism in tobacco .


BACKGROUND AND AIMS : Rhizomes are underground stems with meristematic tissues capable of generating shoots and roots .

However , mechanisms controlling rhizome formation and growth are yet to be completely understood .

The objectives of this study were to investigate whether rhizome development could be regulated by cytokinins ( CKs ) and gibberellic acids ( GAs ) , and determine underlying mechanisms of regulation of rhizome formation and growth of tall fescue ( Festuca arundinacea ) by a CK or GA through proteomic and transcript analysis .

METHODS : A rhizomatous genotype of tall fescue ( ' BR ' ) plants were treated with 6-benzylaminopurine ( BAP , a synthetic cytokinin ) or GA3 in hydroponic culture in growth chambers .

Furthermore , comparative proteomic analysis of two-dimensional electrophoresis and mass spectrometry were performed to investigate proteins and associated metabolic pathways imparting increased rhizome number by BAP and rhizome elongation by GA3 KEY RESULTS : BAP stimulated rhizome formation while GA3 promoted rhizome elongation .

Proteomic analysis identified 76 differentially expressed proteins ( DEPs ) due to BAP treatment and 37 DEPs due to GA3 treatment .

Cytokinin-related genes and cell division-related genes were upregulated in the rhizome node by BAP and gibberellin-related and cell growth-related genes in the rhizome by GA3 CONCLUSIONS : Most of the BAP- or GA-responsive DEPs were involved in respiratory metabolism and amino acid metabolism .

Transcription analysis demonstrated that genes involved in hormone metabolism , signalling pathways , cell division and cell-wall loosening were upregulated by BAP or GA3 The CK and GA promoted rhizome formation and growth , respectively , by activating metabolic pathways that supply energy and amino acids to support cell division and expansion during rhizome initiation and elongation in tall fescue .


BACKGROUND : Jasmonic acid ( JA ) and methyl jasmonate ( MeJA ) regulate plant development , resistance to stress , and insect attack by inducing specific gene expression .

However , little is known about the mechanism of plant defense against herbivore attack at a protein level .

Using a high-resolution 2-D gel , we identified 62 MeJA-responsive proteins and measured protein expression level changes .

RESULTS : Among these 62 proteins , 43 proteins levels were increased while 11 proteins were decreased .

We also found eight proteins uniquely expressed in response to MeJA treatment .

Data are available via ProteomeXchange with identifier PXD001793 .

The proteins identified in this study have important biological functions including photosynthesis and energy related proteins ( 38.4 % ) , protein folding , degradation and regulated proteins ( 15.0 % ) , stress and defense regulated proteins ( 11.7 % ) , and redox-responsive proteins ( 8.3 % ) .

The expression levels of four important genes were determined by qRT-PCR analysis .

The expression levels of these proteins did not correlate well with their translation levels .

To test the defense functions of the differentially expressed proteins , expression vectors of four protein coding genes were constructed to express in-fusion proteins in E. coli .

The expressed proteins were used to feed Ostrinia furnacalis , the Asian corn borer ( ACB ) .

Our results demonstrated that the recombinant proteins of pathogenesis-related protein 1 ( PR1 ) and thioredoxin M-type , chloroplastic precursor ( TRXM ) showed the significant inhibition on the development of larvae and pupae .

CONCLUSIONS : We found MeJA could not only induce plant defense mechanisms to insects , it also enhanced toxic protein production that potentially can be used for bio-control of ACB .


BACKGROUND : Plants respond to various stress stimuli by activating an enhanced broad-spectrum defensive ability .

The development of novel resistance inducers represents an attractive , alternative crop protection strategy .

In this regard , hexanoic acid ( Hxa , a chemical elicitor ) and azelaic acid ( Aza , a natural signaling compound ) have been proposed as inducers of plant defense , by means of a priming mechanism .

Here , we investigated both the mode of action and the complementarity of Aza and Hxa as priming agents in Nicotiana tabacum cells in support of enhanced defense .

RESULTS : Metabolomic analyses identified signatory biomarkers involved in the establishment of a pre-conditioned state following Aza and Hxa treatment .

Both inducers affected the metabolomes in a similar manner and generated common biomarkers : caffeoylputrescine glycoside , cis-5-caffeoylquinic acid , feruloylglycoside , feruloyl-3-methoxytyramine glycoside and feruloyl-3-methoxytyramine conjugate .

Subsequently , quantitative real time-PCR was used to investigate the expression of inducible defense response genes : phenylalanine ammonia lyase , hydroxycinnamoyl CoA quinate transferase and hydroxycinnamoyl transferase to monitor activation of the early phenylpropanoid pathway and chlorogenic acids metabolism , while ethylene response element-binding protein , small sar1 GTPase , heat shock protein 90 , RAR1 , SGT1 , non-expressor of PR genes 1 and thioredoxin were analyzed to report on signal transduction events .

Pathogenesis-related protein 1a and defensin were quantified to investigate the activation of defenses regulated by salicylic acid and jasmonic acid respectively .

The qPCR results revealed differential expression kinetics and , in general ( except for NPR1 , Thionin and PR1a ) , the relative gene expression ratios observed in the Hxa-treated cells were significantly greater than the expression observed in the cells treated with Aza .

CONCLUSIONS : The results indicate that Aza and Hxa have a similar priming effect through activation of genes involved in the establishment of systemic acquired resistance , associated with enhanced synthesis of hydroxycinnamic acids and related conjugates .


The plant-signaling molecules salicylic acid ( SA ) and jasmonic acid ( JA ) play an important role in induced disease resistance pathways .

Cross-talk between SA- and JA-dependent pathways can result in inhibition of JA-mediated defense responses .

We investigated possible antagonistic interactions between the SA-dependent systemic acquired resistance ( SAR ) pathway , which is induced upon pathogen infection , and the JA-dependent induced systemic resistance ( ISR ) pathway , which is triggered by nonpathogenic Pseudomonas rhizobacteria .

In Arabidopsis thaliana , SAR and ISR are effective against a broad spectrum of pathogens , including the foliar pathogen Pseudomonas syringae pv . tomato ( Pst ) .

Simultaneous activation of SAR and ISR resulted in an additive effect on the level of induced protection against Pst .

In Arabidopsis genotypes that are blocked in either SAR or ISR , this additive effect was not evident .

Moreover , induction of ISR did not affect the expression of the SAR marker gene PR-1 in plants expressing SAR .

Together , these observations demonstrate that the SAR and the ISR pathway are compatible and that there is no significant cross-talk between these pathways .

SAR and ISR both require the key regulatory protein NPR1 .

Plants expressing both types of induced resistance did not show elevated Npr1 transcript levels , indicating that the constitutive level of NPR1 is sufficient to facilitate simultaneous expression of SAR and ISR .

These results suggest that the enhanced level of protection is established through parallel activation of complementary , NPR1-dependent defense responses that are both active against Pst .

Therefore , combining SAR and ISR provides an attractive tool for the improvement of disease control .


Two key genes in terpenoid indole alkaloid biosynthesis , Tdc and Str , encoding tryptophan decarboxylase and strictosidine synthase , respectively , are coordinately induced by fungal elicitors in suspension-cultured Catharanthus roseus cells .

We have studied the roles of the jasmonate biosynthetic pathway and of protein phosphorylation in signal transduction initiated by a partially purified elicitor from yeast extract .

In addition to activating Tdc and Str gene expression , the elicitor also induced the biosynthesis of jasmonic acid .

The jasmonate precursor alpha-linolenic acid or methyl jasmonate ( MeJA ) itself induced Tdc and Str gene expression when added exogenously .

Diethyldithiocarbamic acid , an inhibitor of jasmonate biosynthesis , blocked both the elicitor-induced formation of jasmonic acid and the activation of terpenoid indole alkaloid biosynthetic genes .

The protein kinase inhibitor K-252a abolished both elicitor-induced jasmonate biosynthesis and MeJA-induced Tdc and Str gene expression .

Analysis of the expression of Str promoter/gusA fusions in transgenic C. roseus cells showed that the elicitor and MeJA act at the transcriptional level .

These results demonstrate that the jasmonate biosynthetic pathway is an integral part of the elicitor-triggered signal transduction pathway that results in the coordinate expression of the Tdc and Str genes and that protein kinases act both upstream and downstream of jasmonates .


Genome wide association studies enabled prediction of many candidate genes for flowering , maturity and plant height under differing day-length conditions .

Some genes were envisaged only from derived B. rapa .

Flowering and plant height are the key life history traits .

These are crucial for adaptation and productivity .

Current investigations aimed to examine genotypic differences governing days to flowering , maturity and plant height under contrasting day-length conditions ; and identify genomic regions governing the observed phenotypic variations .

An association panel comprising 195 inbred lines , representing natural ( NR ) and derived ( DR ) forms of Brassica rapa ( AA ; 2n = 20 ) , was evaluated at two sowing dates and two locations , representing different day-length regimes .

Derived B. rapa is a unique pre-breeding material extracted from B. juncea ( AABB ; 2n = 36 ) .

Population structure analysis , using DArT genotypes established derived B. rapa as a genetic resource distinct from natural B. rapa .

Genome wide association studies facilitated detection of many trait associated SNPs .

Chromosomes A03 , A05 and A09 harboured majority of these .

Functional annotation of the associated SNPs and surrounding genome space(s ) helped to predict 43 candidate genes .

Many of these were predicted under specific day-length conditions .

Important among these were the genes encoding floral meristem identity ( SPL3 , SPL15 , AP3 , BAM2 ) , photoperiodic responses ( COL2 , AGL18 , SPT , NF-YC4 ) , gibberellic acid biosynthesis ( GA1 ) and regulation of flowering ( EBS ) .

Some of the predicted genes were detected for DR subpanel alone .

Genes controlling hormones , auxins and gibberellins appeared important for the regulation of plant height .

Many of the significant SNPs were located on chromosomes harbouring previously reported QTLs and candidate genes .

The identified loci may be used for marker-assisted selection after due validation .


BACKGROUND AND AIMS : Selected beneficial Pseudomonas spp . strains have the ability to influence root architecture in Arabidopsis thaliana by inhibiting primary root elongation and promoting lateral root and root hair formation .

A crucial role for auxin in this long-term ( 1week ) , long-distance plant-microbe interaction has been demonstrated .

METHODS : Arabidopsis seedlings were cultivated in vitro on vertical plates and inoculated with pathogenic strains Pseudomonas syringae pv . maculicola ( Psm ) and P. syringae pv . tomato DC3000 ( Pst ) , as well as Agrobacterium tumefaciens ( Atu ) and Escherichia coli ( Eco ) .

Root hair lengths were measured after 24 and 48h of direct exposure to each bacterial strain .

Several Arabidopsis mutants with impaired responses to pathogens , impaired ethylene perception and defects in the exocyst vesicle tethering complex that is involved in secretion were also analysed .

KEY RESULTS : Arabidopsis seedling roots infected with Psm or Pst responded similarly to when infected with plant growth-promoting rhizobacteria ; root hair growth was stimulated and primary root growth was inhibited .

Other plant- and soil-adapted bacteria induced similar root hair responses .

The most compromised root hair growth stimulation response was found for the knockout mutants exo70A1 and ein2 .

The single immune pathways dependent on salicylic acid , jasmonic acid and PAD4 are not directly involved in root hair growth stimulation ; however , in the mutual cross-talk with ethylene , they indirectly modify the extent of the stimulation of root hair growth .

The Flg22 peptide does not initiate root hair stimulation as intact bacteria do , but pretreatment with Flg22 prior to Psm inoculation abolished root hair growth stimulation in an FLS2 receptor kinase-dependent manner .

These early response phenomena are not associated with changes in auxin levels , as monitored with the pDR5::GUS auxin reporter .

CONCLUSIONS : Early stimulation of root hair growth is an effect of an unidentified component of living plant pathogenic bacteria .

The root hair growth response is triggered in the range of hours after bacterial contact with roots and can be modulated by FLS2 signalling .

Bacterial stimulation of root hair growth requires functional ethylene signalling and an efficient exocyst-dependent secretory machinery .


Jasmonate ( JA ) signaling is a key mediator of plant development and defense which arose during plants transition from an aqueous to terrestrial environment .

Elucidating the evolution of JA signaling is important for understanding plant development , defense , and production of specialized metabolites .

The lineage of key protein domains characterizing JA signaling factors was traced to identify the origins of CORONITINE INSENSITIVE 1 ( COI1 ) , JASMONATE ZIM-DOMAIN ( JAZ ) , NOVEL INTERACTOR OF JAZ , MYC2 , TOPLESS , and MEDIATOR SUBUNIT 25 .

Charophytes do not possess genes encoding key JA signaling components , including COI1 , JAZ , MYC2 , and the JAZ-interacting bHLH factors , yet their orthologs are present in bryophytes .

TIFY family genes were found in charophyta and chlorophya algae .

JAZs evolved from ZIM genes of the TIFY family through changes to several key amino acids .

Dating placed the origin of JA signaling 515 to 473 million years ago during the middle Cambrian to early Ordovician periods .

This time is known for rapid biodiversification and mass extinction events .

An increased predation from the diversifying and changing fauna may have driven evolution of JA signaling and plant defense .