Gibberellin ( GA ) regulates various plant growth and developmental processes , but its role in pathogen attack , and especially nematode-plant interactions , still remains to be elucidated .

An in-depth characterization of the role of GA in nematode infection was conducted using mutant lines of rice , chemical inhibitors , and phytohormone measurements .

Our results showed that GA influences rice-Meloidogyne graminicola interactions in a concentration-dependent manner .

Foliar spray of plants with a low concentration of gibberellic acid enhanced nematode infection .

Biosynthetic and signaling mutants confirmed the importance of gibberellin for rice susceptibility to M. graminicola infection .

Our study also demonstrates that GA signaling suppresses jasmonate (JA)-mediated defense against M. graminicola , and likewise the JA-induced defense against M. graminicola requires SLENDER RICE1 (SLR1)-mediated repression of the GA pathway .

In contrast to observations from other plant-pathogen interactions , GA plays a dominant role over JA in determining susceptibility to M. graminicola in rice .

This GA-induced nematode susceptibility was largely independent of auxin biosynthesis , but relied on auxin transport .

In conclusion , we showed that GA-JA antagonistic crosstalk is at the forefront of the interaction between rice and M. graminicola , and SLR1 plays a central role in the JA-mediated defense response in rice against this nematode .


The mitogen-activated protein kinase ( MAPK ) signaling cascade is critical for regulating plant defense systems against various kinds of pathogen and environmental stresses .

One component of this cascade , the MAP kinase kinases ( MAPKK ) , has not yet been shown to be induced in plants following biotic attacks , such as those by insects and fungi .

We describe here a gene coding for a blast ( Magnaporthe grisea)- and insect ( Nilaparvata lugens)-responsive putative MAPK kinase , OmMKK1 ( Oryza minuta MAPKK 1 ) , which was identified in a library of O. minuta expressed sequence tags ( ESTs ) .

Two copies of OmMKK1 are present in the O. minuta genome .

They encode a predicted protein with molecular mass 39 kDa and pI of 6.2 .

Transcript patterns following imbibition of plant hormones such as methyl jasmonic acid ( MeJA ) , ethephone , salicylic acid ( SA ) and abscisic acid ( ABA ) , as well as exposure to methyl viologen ( MV ) , revealed that the expression of OmMKK1 is related to defense response signaling pathways .

A comparative analysis of OmMKK1 and its O. sativa ortholog OsMKK1 showed that both were induced by stress-related hormones and biotic stresses , but that the kinetics of their responses differed despite their high amino acid sequence identity ( 96 % ) .


Pseudomonas syringae pv tomato DC3000 ( Pst DC3000 ) , which causes disease in tomato ( Solanum lycopersicum ) and Arabidopsis ( Arabidopsis thaliana ) , produces coronatine ( COR ) , a non-host-specific phytotoxin .

COR , which functions as a jasmonate mimic , is required for full virulence of Pst DC3000 and for the induction of chlorosis in host plants .

Previous genetic screens based on insensitivity to COR and/or methyl jasmonate identified several potential targets for COR and methyl jasmonate .

In this study , we utilized Nicotiana benthamiana and virus-induced gene silencing to individually reduce the expression of over 4,000 genes .

The silenced lines of N. benthamiana were then screened for altered responses to purified COR .

Using this forward genetics approach , several genes were identified with altered responses to COR .

These were designated as ALC ( for altered COR response ) genes .

When silenced , one of the identified genes , ALC1 , produced a hypersensitive/necrosis-like phenotype upon COR application in a Coronatine-Insensitive1 (COI1)-dependent manner .

To understand the involvement of ALC1 during the Pst DC3000-host interaction , we used the nucleotide sequence of ALC1 and identified its ortholog in Arabidopsis ( Thylakoid Formation1 [ THF1 ] ) and tomato ( SlALC1 ) .

In pathogenicity assays performed on Arabidopsis thf1 mutant and SlALC1-silenced tomato plants , Pst DC3000 induced accelerated coalescing necrotic lesions .

Furthermore , we showed that COR affects ALC1 localization in chloroplasts in a COI1-dependent manner .

In conclusion , our results show that the virus-induced gene silencing-based forward genetic screen has the potential to identify new players in COR signaling and disease-associated necrotic cell death .


Calcium-dependent protein kinases ( CPKs ) play important roles in multiple signal transduction pathways but the precise role of individual CPK is largely unknown .

We isolated two cDNAs encoding two CPK isoforms ( Cicer arietinum CPKs-CaCPK1 and CaCPK2 ) of chickpea .

Their expression in various organs and in response to various phytohormones , and dehydration , high salt stress and fungal spore in excised leaves as well as localization in leaf and stem tissues were analyzed in this study .

CaCPK1 protein and its activity were ubiquitous in all tissues examined .

In contrast , CaCPK2 transcript , CaCPK2 protein and its activity were almost undetectable in flowers and fruits .

Both CaCPK1 and CaCPK2 transcripts and proteins were abundant in roots but in minor quantities in leaves and stems .

Of the three phytohormones tested , viz . indole-3-acetic acid ( IAA ) , gibberellin ( GA(3 ) ) and benzyladenine ( BA ) , only BA increased both CaCPK1 and CaCPK2 transcripts , proteins and their activities .

GA(3 ) induced accumulation of CaCPK2 transcript and protein but CaCPK1 remained unaffected .

The expression of CaCPK1 and CaCPK2 in leaves was enhanced in response to high salt stress .

Treatments with Aspergillus sp. spores increased expression of CaCPK1 in chickpea leaf tissue but had no effect on CaCPK2 .

Excised leaves subjected to dehydration showed increase in CaCPK2 expression but not in CaCPK1 .

Both isoforms were located in the plasma membrane ( PM ) and chloroplast membrane of leaf mesophyll cells as well as in the PM of stem xylem parenchyma cells .

These results suggest specific roles for CaCPK isoforms in phytohormone/defense/stress signaling pathways .


Plants coordinate and tightly regulate pathogen defense by the mostly antagonistic salicylate (SA)- and jasmonate (JA)-mediated signaling pathways .

Here , we show that the previously uncharacterized glucosyltransferase UGT76B1 is a novel player in this SA-JA signaling crosstalk .

UGT76B1 was selected as the top stress-induced isoform among all 122 members of the Arabidopsis thaliana UGT family .

Loss of UGT76B1 function leads to enhanced resistance to the biotrophic pathogen Pseudomonas syringae and accelerated senescence but increased susceptibility toward necrotrophic Alternaria brassicicola .

This is accompanied by constitutively elevated SA levels and SA-related marker gene expression , whereas JA-dependent markers are repressed .

Conversely , UGT76B1 overexpression has the opposite effect .

Thus , UGT76B1 attenuates SA-dependent plant defense in the absence of infection , promotes the JA response , and delays senescence .

The ugt76b1 phenotypes were SA dependent , whereas UGT76B1 overexpression indicated that this gene possibly also has a direct effect on the JA pathway .

Nontargeted metabolomic analysis of UGT76B1 knockout and overexpression lines using ultra-high-resolution mass spectrometry and activity assays with the recombinant enzyme led to the ab initio identification of isoleucic acid ( 2-hydroxy-3-methyl-pentanoic acid ) as a substrate of UGT76B1 .

Exogenously applied isoleucic acid increased resistance against P. syringae infection .

These findings indicate a novel link between amino acid-related molecules and plant defense that is mediated by small-molecule glucosylation .


The potassium ion ( K+ ) is vital for plant growth and development , and K+-deprivation leads to reduced crop yields .

Here we describe phenotypic , transcriptomic , and mutant analyses to investigate the signaling mechanisms mediating root architectural changes in Arabidopsis ( Arabidopsis thaliana ) Columbia .

We showed effects on root architecture are mediated through a reduction in cell division in the lateral root ( LR ) meristems , the rate of LR initiation is reduced but LR density is unaffected , and primary root growth is reduced only slightly .

This was primarily regulated through gibberellic acid ( GA ) signaling , which leads to the accumulation of growth-inhibitory DELLA proteins .

The short LR phenotype was rescued by exogenous application of GA but not of auxin or by the inhibition of ethylene signaling .

RNA-seq analysis showed upregulation by K+-deprivation of the transcription factors JUNGBRUNNEN1 ( JUB1 ) and the C-repeat-binding factor (CBF)/dehydration-responsive element-binding factor 1 regulon , which are known to regulate GA signaling and levels that regulate DELLAs .

Transgenic overexpression of JUB1 and CBF1 enhanced responses to K+ stress .

Attenuation of the reduced LR growth response occurred in mutants of the CBF1 target gene SFR6 , implicating a role for JUB1 , CBF1 , and SFR6 in the regulation of LR growth in response to K+-deprivation via DELLAs .

We propose this represents a mechanism to limit horizontal root growth in conditions where K+ is available deeper in the soil .


Effects of α-ketol linolenic acid ( KODA ) application on endogenous abscisic acid ( ABA ) , jasmonic acid ( JA ) , and aromatic volatiles were investigated in ' Kyoho ' grapes ( Vitis labrusca × Vitis vinifera ) infected by a pathogen ( Glomerella cingulata ) .

The expressions of 9-cis-epoxycarotenoid dioxygenase ( VvNCED1 ) , ABA 8'-hydroxylase ( VvCYP707A1 ) , lipoxygenase ( VvLOX ) , and allene oxide synthase ( VvAOS ) were also examined .

The grape berries were dipped in 0.1mM KODA solution before inoculation with the pathogen and stored at 25 ° C for 12 days .

The development of infection was significantly suppressed upon KODA treatment .

Endogenous ABA , JA and phaseic acid ( PA ) were induced in inoculated berries .

KODA application before inoculation increased endogenous ABA , PA and JA through the activation of VvNCED1 , VvCYP707A1 and VvAOS genes , respectively .

In addition , terpenes , methyl salicylate ( Me-SA ) and C6-aldehydes such as (E)-2-hexenal and cis-3-hexenal associated with fungal resistance also increased in KODA-treated berries during storage .

These results suggest that the synergistic effect of JA , ABA , and some aromatic volatiles induced by KODA application may provide resistance to pathogen infection in grape berries .


Apoplast , the diffusional space between plant cell plasma membranes , is an important medium for signaling within and between the cells .

Apoplastic reactive oxygen species ( ROS ) are crucial signaling molecules in various biological processes .

ROS signaling is interconnected with the response to several hormones , including jasmonic acid ( JA ) , salicylic acid ( SA ) and ethylene .

Using ozone ( O3 ) to activate apoplastic ROS signaling , we performed global and targeted analysis of transcriptional changes and cell death assays to dissect the contribution of hormone signaling and various transcription factors ( TFs ) in the regulation of gene expression and cell death .

The contributions of SA , JA , and ethylene were assessed through analysis of single , double , and triple mutants deficient in biosynthesis or signaling for all three hormones .

Even in the triple mutant , the global gene expression responses to O3 were mostly similar to the wild-type .

Cell death in the JA receptor mutant coi1 - 16 was suppressed by impairment of the NADPH oxidase RBOHF , suggesting a role for a ROS signal in limiting the spread of cell death .

In response to apoplastic ROS , there is not a single signaling pathway that regulates gene expression or cell death .

Instead , several pathways regulate the apoplastic ROS response via combinatorial or overlapping mechanisms .


In tobacco ( Nicotiana tabacum ) , nicotine is the predominant alkaloid .

It is produced in the roots and accumulated mainly in the leaves .

Jasmonates play a central signaling role in damage-induced nicotine formation .

The genome sequence of tobacco provides us an almost complete inventory of structural and regulatory genes involved in nicotine pathway .

Phylogenetic and expression analyses revealed a series of structural genes of the nicotine pathway , forming a regulon , under the control of jasmonate-responsive ETHYLENE RESPONSE FACTOR ( ERF ) transcription factors .

The duplication of NAD and polyamine metabolic pathways and the subsequent recruitment of duplicated primary metabolic genes into the nicotine biosynthesis regulon were suggested to be the drivers for pyridine and pyrrolidine ring formation steps early in the pathway .

Transcriptional regulation by ERF and cooperatively acting MYC2 transcription factors are corroborated by the frequent occurrence of cognate cis-regulatory elements of the factors in the promoter regions of the downstream structural genes .

The allotetraploid tobacco has homologous clusters of ERF genes on different chromosomes , which are possibly derived from two ancestral diploids and include either nicotine-controlling ERF189 or ERF199 A large chromosomal deletion was found within one allele of the nicotine-controlling NICOTINE2 locus , which is part of one of the ERF gene clusters , and which has been used to breed tobacco cultivars with a low-nicotine content .


Both gibberellic acid and abscisic acid inhibit the light induced synthesis of amaranthin in Amaranthus tricolor seedlings .

The auxin , indolyl-3-acetic acid has no effect .

The protein/RNA inhibitors , cycloheximide and 8-azaguanine , also reduced the levels of amaranthin produced .


Gibberellic acid ( GA(3 ) ) promotes and continuous gold light inhibits germination of seeds of a dwarf strain ( WB-2 ) of watermelon [ Citrullus lanatus ( Thunb . ) Matsu . and Nakai ] .

Osmotic inhibition of germination with mannitol in light-grown seeds of WB-2 was only slightly reversed by GA(3 ) at the concentrations used , whereas , GA(3 ) substantially relieved osmotic inhibition in dark-grown seeds .

The effects of GA(3 ) and gold light on development of catalase and invertase activities and on levels of free amino acids in germinating seeds of WB-2 were examined .

Light depressed development of catalase and invertase activity .

Levels of free amino acids increased more slowly in embryonic axes of light- than dark-incubated seeds , but in cotyledons higher levels of amino acids were maintained in light-grown seeds .

GA(3 ) accelerated the development of catalase activity in whole embryos and invertase activity in embryonic axes , but did not significantly affect invertase activity in cotyledons during germination .

GA(3 ) had little effect on amino acid pools in cotyledons and embryonic axes .


Effects of ethylene , gibberellins , and kinetin on the germination of two lots of Chenopodium album L. seeds , collected from the field in 1982 and 1983 , were studied in relation to the availability of nitrate .

The experiments were conducted in darkness and at temperatures ranging from 12 to 32 degrees C. Ethylene induced over 75 % germination in the 1983 seed but had little effect on the 1982 seed .

Nitrate was only slightly promotive in either of the two seed lots .

A combination of ethylene and nitrate , however , acted synergistically on 1982 seed , resulting in as much germination as that induced in 1983 seed by ethylene alone .

In 1983 seed , a combination of ethylene and nitrate was only marginally more effective than ethylene .

A similar relationship was observed in the effects of gibberellic acid(4 + 7 ) ( GA(4 + 7 ) ) and nitrate on seeds from the two lots .

The 1982 seed , which responded synergistically to combinations of nitrate with ethylene or GA(4 + 7 ) was found to contain an extremely low endogenous level of nitrate as compared to 1983 seed .

Thus , high levels of either endogenous or applied nitrate appeared to enhance the germination response to ethylene or GA(4 + 7).Kinetin had no effect on 1982 seed and only a small promotive effect on 1983 seed .

There was no synergism between kinetin and nitrate in either of the seed lots .


The plant-specific WUSCHEL-related homeobox ( WOX ) nuclear proteins have important roles in the transcriptional regulation of many developmental processes .

Among the rice ( Oryza sativa ) WOX proteins , a loss of OsWOX3A function in narrow leaf2 ( nal2 ) nal3 double mutants ( termed nal2/3 ) causes pleiotropic effects , such as narrow and curly leaves , opened spikelets , narrow grains , more tillers , and fewer lateral roots , but almost normal plant height .

To examine OsWOX3A function in more detail , transgenic rice overexpressing OsWOX3A ( OsWOX3A-OX ) were generated ; unexpectedly , all of them consistently exhibited severe dwarfism with very short and wide leaves , a phenotype that resembles that of gibberellic acid (GA)-deficient or GA-insensitive mutants .

Exogenous GA3 treatment fully rescued the developmental defects of OsWOX3A-OX plants , suggesting that constitutive overexpression of OsWOX3A downregulates GA biosynthesis .

Quantitative analysis of GA intermediates revealed significantly reduced levels of GA20 and bioactive GA1 in OsWOX3A-OX , possibly due to downregulation of the expression of KAO , which encodes ent-kaurenoic acid oxidase , a GA biosynthetic enzyme .

Yeast one-hybrid and electrophoretic mobility shift assays revealed that OsWOX3A directly interacts with the KAO promoter .

OsWOX3A expression is drastically and temporarily upregulated by GA3 and downregulated by paclobutrazol , a blocker of GA biosynthesis .

These data indicate that OsWOX3A is a GA-responsive gene and functions in the negative feedback regulation of the GA biosynthetic pathway for GA homeostasis to maintain the threshold levels of endogenous GA intermediates throughout development .


BACKGROUND : Salt stress is a devastating environmental stress that causes plant growth inhibition and yield reduction .

OBJECTIVE : The identification of salt-tolerant genes brings hope for the generation of salinity-tolerant crop plants through molecular breeding .

METHODS : In this study , one salt-sensitive and one salt-tolerant maize inbred line were screened from 242 maize inbred lines .

Reactive oxygen species (ROS)-related enzyme activities were detected and salt-responsive comparative transcriptome analysis was performed for control and 220 mM NaCl treated maize leaves .

RESULTS : Salt-tolerant maize inbred line ( L87 ) showed higher ROS-related enzyme ( SOD , POD , APX and CAT ) activities and accumulated relatively lower levels of ROS under salt stress .

Of the total DEGs , 1856 upregulated DEGs were specific to L87 , including stress tolerance-related members of the 70kDa family of heat shock proteins ( Hsp70s ) and aquaporins .

The DEGs involved in the abscisic acid ( ABA ) , ethylene , jasmonic acid ( JA ) and salicylic acid ( SA ) signal transduction pathways may determine the difference in salt tolerance between the two varieties , especially one central component SnRK2 , that positively regulates ABA signaling and was only upregulated in L87 .

Analysis of DEGs related to ROS scavenging showed that some peroxidase ( POD ) , glutathione S-transferase ( GST ) , catalase ( CAT ) and superoxide dismutase ( SOD ) genes specific to L87 probably enhanced its salt tolerance .

The analysis of differentially expressed transcription factors ( TFs ) suggested that WRKY TFs could contribute to the difference in salt tolerance between the two maize lines .

CONCLUSION : Compared with Salt-sensitive maize inbred line ( L29 ) , L87 exhibits specific regulatory mechanisms related to salt tolerance , including plant hormone interactions , ROS scavenging and the regulation of TFs .

Our study identifies new candidate genes that may regulate maize tolerance to salt stress and provides useful information for breeding maize with high salt resistance .


Increasing sucrose from 20 to 50 g l(-1 ) in Uncaria tomentosa cell suspension cultures enhanced ursolic acid and oleanolic acid production from 129 + /- 61 to 553 + /- 193 microg g(-1 ) cell dry wt .

The maximal concentration of both triterpenes ( 1680 + /- 39 microg g(-1 ) cell dry wt ) was 8 days after elicitation by jasmonic acid , while yeast extract or citrus pectin treatments produced 1189 + /- 20 or 1120 + /- 26 microg g(-1 ) cell dry wt , respectively .

The ratio of ursolic acid : oleanolic acid was constant at 70:30 .


Menthol mint ( Mentha arvensis L. ) cultivation is significantly affected by the heavy metals like cadmium ( Cd ) which also imposes severe health hazards .

Two menthol mint cultivars namely Kosi and Kushal were evaluated under Cd stress conditions .

Impact of plant growth regulators ( PGRs ) like salicylic acid ( SA ) , gibberellic acid ( GA(3 ) ) and triacontanol ( Tria ) on Cd stress tolerance was assessed .

Reduced growth , photosynthetic parameters , mineral nutrient concentration , and increased oxidative stress biomarkers like electrolyte leakage , malondialdehyde , and hydrogen peroxide contents were observed under Cd stress .

Differential upregulation of proline content and antioxidant activities under Cd stress was observed in both the cultivars .

Interestingly , low electrolyte leakage , lipid peroxidation , hydrogen peroxide and Cd concentration in leaves were observed in Kushal compared to Kosi .

Among all the PGRs tested , SA proved to be the best in improving Cd-stress tolerance in both the cultivars but Kushal responded better than Kosi .


Jasmonates ( JAs ) are signals in plant stress responses and development .

One of the first observed and prominent responses to JAs is the induction of biosynthesis of different groups of secondary compounds .

Among them are nicotine , isoquinolines , glucosinolates , anthocyanins , benzophenanthridine alkaloids , artemisinin , and terpenoid indole alkaloids ( TIAs ) , such as vinblastine .

This brief review describes modes of action of JAs in the biosynthesis of anthocyanins , nicotine , TIAs , glucosinolates and artemisinin .

After introducing JA biosynthesis , the central role of the SCF(COI1)-JAZ co-receptor complex in JA perception and MYB-type and MYC-type transcription factors is described .

Brief comments are provided on primary metabolites as precursors of secondary compounds .

Pathways for the biosynthesis of anthocyanin , nicotine , TIAs , glucosinolates and artemisinin are described with an emphasis on JA-dependent transcription factors , which activate or repress the expression of essential genes encoding enzymes in the biosynthesis of these secondary compounds .

Applied aspects are discussed using the biotechnological formation of artemisinin as an example of JA-induced biosynthesis of secondary compounds in plant cell factories .


BACKGROUND : The plant-specific TCP transcription factor family , which is involved in the regulation of cell growth and proliferation , performs diverse functions in multiple aspects of plant growth and development .

However , no comprehensive analysis of the TCP family in watermelon ( Citrullus lanatus ) has been undertaken previously .

RESULTS : A total of 27 watermelon TCP encoding genes distributed on nine chromosomes were identified .

Phylogenetic analysis clustered the genes into 11 distinct subgroups .

Furthermore , phylogenetic and structural analyses distinguished two homology classes within the ClTCP family , designated Class I and Class II .

The Class II genes were differentiated into two subclasses , the CIN subclass and the CYC/TB1 subclass .

The expression patterns of all members were determined by semi-quantitative PCR .

The functions of two ClTCP genes , ClTCP14a and ClTCP15 , in regulating plant height were confirmed by ectopic expression in Arabidopsis wild-type and ortholog mutants .

CONCLUSIONS : This study represents the first genome-wide analysis of the watermelon TCP gene family , which provides valuable information for understanding the classification and functions of the TCP genes in watermelon .


Shoot apices of Lolium temulentum excised after exposure of the plants to one long day ( LD ) undergo floral development in vitro , whereas those excised from plants in short days ( SD ) remain vegetative .

Floral differentiation in vitro is reasonably normal and responds quantitatively to the preceding LD induction when three conditions are met .

First , excision must not precede the arrival at the apex of the LD stimulus from the leaves .

This appears to begin about 22 h after the start of the LD and is completed after a further 14 h , by which time all isolated apices have become capable of initiating inflorescence differentiation , i.e. florally determined .

Second , for apices excised on the day after the LD ( Day II ) or early on Day III , the presence of gibberellic acid in the medium is required for floral differentiation to occur in most explants .

By contrast , neither kinetin ( N(6)-furfurylaminopurine ) nor indole-3-acetic acid is required or beneficial , while abscisic acid in the medium is inhibitory to both survival and floral differentiation in excised apices .

The third requirement is for an adequate supply of sugar , particularly after floral differentiation begins .

Sucrose is taken up rapidly to reach high levels in the excised apices , but high sugar concentration in the medium , either alone or with gibberellic acid , does not suffice for floral differentiation to begin , and there is an absolute requirement for receipt of the LD stimulus .


Autophagy is an evolutionarily conserved intracellular process for vacuolar degradation of cytoplasmic components .

In higher plants , autophagy defects result in early senescence and excessive immunity-related programmed cell death ( PCD ) irrespective of nutrient conditions ; however , the mechanisms by which cells die in the absence of autophagy have been unclear .

Here , we demonstrate a conserved requirement for salicylic acid ( SA ) signaling for these phenomena in autophagy-defective mutants ( atg mutants ) .

The atg mutant phenotypes of accelerated PCD in senescence and immunity are SA signaling dependent but do not require intact jasmonic acid or ethylene signaling pathways .

Application of an SA agonist induces the senescence/cell death phenotype in SA-deficient atg mutants but not in atg npr1 plants , suggesting that the cell death phenotypes in the atg mutants are dependent on the SA signal transducer NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 .

We also show that autophagy is induced by the SA agonist .

These findings imply that plant autophagy operates a novel negative feedback loop modulating SA signaling to negatively regulate senescence and immunity-related PCD .


The Arabidopsis Jasmonate ZIM-domain proteins ( JAZs ) act as substrates of SCF(COI1 ) complex to repress their downstream targets , which are essential for JA-regulated plant development and defense .

The bHLH transcription factor MYC2 was found to interact with JAZs and mediate JA responses including JA-inhibitory root growth .

Here , we identified another bHLH transcription factor MYC3 which directly interacted with JAZs by virtue of its N-terminal region to regulate JA responses .

The transgenic plants with overexpression of MYC3 exhibited hypersensitivity in JA-inhibitory root elongation and seedling development .

The JAZ-interacting pattern and the JA-induced expression pattern of MYC3 were distinguishable from those of MYC2 .

We speculate that MYC3 and MYC2 may have redundant but also distinguishable functions in regulation of JA responses .


BACKGROUND : Seed dormancy is controlled by the physiological or structural properties of a seed and the external conditions .

It is induced as part of the genetic program of seed development and maturation .

Seeds with deep physiological embryo dormancy can be stimulated to germinate by a variety of treatments including cold stratification .

Hormonal imbalance between germination inhibitors ( e.g. abscisic acid ) and growth promoters ( e.g. gibberellins ) is the main cause of seed dormancy breaking .

Differences in the status of hormones would affect expression of genes required for germination .

Proteomics offers the opportunity to examine simultaneous changes and to classify temporal patterns of protein accumulation occurring during seed dormancy breaking and germination .

Analysis of the functions of the identified proteins and the related metabolic pathways , in conjunction with the plant hormones implicated in seed dormancy breaking , would expand our knowledge about this process .

RESULTS : A proteomic approach was used to analyse the mechanism of dormancy breaking in Norway maple seeds caused by cold stratification , and the participation of the abscisic ( ABA ) and gibberellic ( GA ) acids .

Forty-four proteins showing significant changes were identified by mass spectrometry .

Of these , eight spots were identified as water-responsive , 18 spots were ABA- and nine GA-responsive and nine spots were regulated by both hormones .

The classification of proteins showed that most of the proteins associated with dormancy breaking in water were involved in protein destination .

Most of the ABA- and GA-responsive proteins were involved in protein destination and energy metabolism .

CONCLUSION : In this study , ABA was found to mostly down-regulate proteins whereas GA up-regulated proteins abundance .

Most of the changes were observed at the end of stratification in the germinated seeds .

This is the most active period of dormancy breaking when seeds pass from the quiescent state to germination .

Seed dormancy breaking involves proteins of various processes but the proteasome proteins , S-adenosylmethionine synthetase , glycine-rich RNA binding protein , ABI3-interacting protein 1 , EF-2 and adenosylhomocysteinase are of particular importance .

The effect of exogenously applied hormones was not a determining factor for total inhibition ( ABA ) or stimulation ( GA ) of Norway maple seed dormancy breaking and germination but proteomic data has proven these hormones play a role .


Signaling networks among multiple phytohormones fine-tune plant defense responses to insect herbivore attack .

Previously , it was reported that the synergistic combination of ethylene ( ET ) and jasmonic acid ( JA ) was required for accumulation of the maize insect resistance1 ( mir1 ) gene product , a cysteine ( Cys ) proteinase that is a key defensive protein against chewing insect pests in maize ( Zea mays ) .

However , this study suggests that mir1-mediated resistance to corn leaf aphid ( CLA ; Rhopalosiphum maidis ) , a phloem sap-sucking insect pest , is independent of JA but regulated by the ET-signaling pathway .

Feeding by CLA triggers the rapid accumulation of mir1 transcripts in the resistant maize genotype , Mp708 .

Furthermore , Mp708 provided elevated levels of antibiosis ( limits aphid population)- and antixenosis ( deters aphid settling)-mediated resistance to CLA compared with B73 and Tx601 maize susceptible inbred lines .

Synthetic diet aphid feeding trial bioassays with recombinant Mir1-Cys Protease demonstrates that Mir1-Cys Protease provides direct toxicity to CLA .

Furthermore , foliar feeding by CLA rapidly sends defensive signal(s ) to the roots that trigger belowground accumulation of the mir1 , signifying a potential role of long-distance signaling in maize defense against the phloem-feeding insects .

Collectively , our data indicate that ET-regulated mir1 transcript accumulation , uncoupled from JA , contributed to heightened resistance to CLA in maize .

In addition , our results underscore the significance of ET acting as a central node in regulating mir1 expression to different feeding guilds of insect herbivores .


Reducing phenylpropanoid biosynthesis in transgenic tobacco compromises systemic acquired resistance ( SAR ) to tobacco mosaic virus , while increasing phenylpropanoid biosynthesis enhances SAR .

Surprisingly , transgenic tobacco plants compromised in SAR exhibit more effective grazing-induced systemic resistance to larvae of Heliothis virescens , whereas induced insect resistance is compromised in transgenic plants with elevated phenylpropanoid levels .

Levels of the phenylpropanoid-derived signal salicylic acid are directly correlated with overall phenylpropanoid biosynthesis in this series of transgenic plants .

Moreover , while pathogen-induced SAR is almost completely compromised in salicylic acid-deficient plants expressing the bacterial nahG salicylate hydroxylase gene , these plants show enhanced grazing-induced insect resistance compared to wild-type .

Hence , suppression of grazing-induced insect resistance is mediated at least in part by salicylic acid and likely reflects salicylic acid inhibition of the synthesis and action of the wound signal jasmonic acid .

We propose that the dual functions of salicylic acid contribute to a signal poise which constrains constitutive expression of disease and insect resistance mechanisms , and reciprocally switches their selective activation .


BACKGROUND AND AIMS : Current strategies for increased crop protection of susceptible tomato plants against pathogen infections include treatment with synthetic chemicals , application of natural pathogen-derived compounds or transfer of resistance genes from wild tomato species within breeding programmes .

In this study , a series of 45 genes potentially involved in defence mechanisms was retrieved from the genome sequence of inbred reference tomato cultivar Solanum lycopersicum ' Heinz 1706 ' .

The aim of the study was to analyse expression of these selected genes in wild and cultivated tomato plants contrasting in resistance to the biotrophic pathogen Oidium neolycopersici , the causative agent of powdery mildew .

Plants were treated either solely with potential resistance inducers or by inducers together with the pathogen .

METHODS : The resistance against O. neolycopersici infection as well as RT-PCR-based analysis of gene expression in response to the oomycete elicitor oligandrin and chemical agent β-aminobutyric acid ( BABA ) were investigated in the highly susceptible domesticated inbred genotype Solanum lycopersicum ' Amateur ' and resistant wild genotype Solanum habrochaites .

KEY RESULTS : Differences in basal expression levels of defensins , germins , β-1,3-glucanases , heveins , chitinases , osmotins and PR1 proteins in non-infected and non-elicited plants were observed between the highly resistant and susceptible genotypes .

Moreover , these defence genes showed an extensive up-regulation following O. neolycopersici infection in both genotypes .

Application of BABA and elicitin induced expression of multiple defence-related transcripts and , through different mechanisms , enhanced resistance against powdery mildew in the susceptible tomato genotype .

CONCLUSIONS : The results indicate that non-specific resistance in the resistant genotype S. habrochaites resulted from high basal levels of transcripts with proven roles in defence processes .

In the susceptible genotype S. lycopersicum ' Amateur ' , oligandrin- and BABA-induced resistance involved different signalling pathways , with BABA-treated leaves displaying direct activation of the ethylene-dependent signalling pathway , in contrast to previously reported jasmonic acid-mediated signalling for elicitins .


Tritrophic interactions involving a biocontrol agent , a pathogen , and a plant have been analyzed predominantly from the perspective of the biocontrol agent .

To explore the adaptive strategies of wheat in response to beneficial , pathogenic , and combined microorganisms , we performed the first comprehensive transcriptomic , proteomic , and biochemical analysis in wheat roots after exposure to Bacillus velezensis CC09 , Gaeumannomyces graminis var . tritici , and their combined colonization , respectively .

The transcriptional or translational programming of wheat roots inoculated with beneficial B. velezensis showed mild alterations compared with that of pathogenic G. graminis var . tritici .

However , the combination of B. velezensis and G. graminis var . tritici activated a larger transcriptional or translational program than for each single microorganism , although the gene expression pattern was similar to that of individual infection by G. graminis var . tritici , suggesting a prioritization of defense against G. graminis var . tritici infection .

Surprisingly , pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity made wheat pretreated with B. velezensis more sensitive to subsequent G. graminis var . tritici infection .

Additionally , B. velezensis triggered a salicylic acid (SA)-dependent mode of induced systemic resistance that resembles pathogen-induced systemic acquired resistance .

Wheat plants mainly depend on SA-mediated resistance , and not that mediated by jasmonic acid ( JA ) , against the necrotrophic pathogen G. graminis var . tritici .

Moreover , SA-JA interactions resulted in antagonistic effects regardless of the type of microorganisms in wheat .

Further enhancement of SA-dependent defense responses such as lignification to the combined infection was shown to reduce the level of induced JA-dependent defense against subsequent infection with G. graminis var . tritici .

Altogether , our results demonstrate how the hexaploid monocot wheat responds to beneficial or pathogenic microorganisms and prolongs the onset of take-all disease through modulation of cell reprogramming and signaling events .


Germination is a process of seed sprouting that facilitates embryo growth .

The breakdown of reserved starch in the endosperm into simple sugars is essential for seed germination and subsequent seedling growth .

At the early stage of germination , gibberellic acid ( GA ) activates transcription factor GAMYB to promote de novo synthesis of isoforms of α-amylase in the aleurone layer and scutellar epithelium of the embryo .

Here , we demonstrate that wheat germination is regulated by plant target of rapamycin ( TOR ) signaling .

TOR is a central component of the essential-nutrient-dependent pathway controlling cell growth in all eukaryotes .

It is known that rapamycin , a highly specific allosteric inhibitor of TOR , is effective in yeast and animal cells but ineffective in most of higher plants likely owing to structural differences in ubiquitous rapamycin receptor FKBP12 .

The action of rapamycin on wheat growth has not been studied .

Our data show that rapamycin inhibits germination of wheat seeds and of their isolated embryos in a dose-dependent manner .

The involvement of Triticum aestivum TOR ( TaTOR ) in wheat germination was consistent with the suppression of wheat embryo growth by specific inhibitors of the TOR kinase : pp242 or torin1 .

Rapamycin or torin1 interfered with GA function in germination because of a potent inhibitory effect on α-amylase and GAMYB gene expression .

The TOR inhibitors selectively targeted the GA-dependent gene expression , whereas expression of the abscisic acid-dependent ABI5 gene was not affected by either rapamycin or torin1 .

To determine whether the TaTOR kinase activation takes place during wheat germination , we examined phosphorylation of a ribosomal protein , T. aestivum S6 kinase 1 ( TaS6K1 ; a substrate of TOR ) .

The phosphorylation of serine 467 ( S467 ) in a hydrophobic motif on TaS6K1 was induced in a process of germination triggered by GA .

Moreover , the germination-induced phosphorylation of TaS6K1 on S467 was dependent on TaTOR and was inhibited by rapamycin or torin1 .

Besides , a gibberellin biosynthesis inhibitor ( paclobutrazol ; PBZ ) blocked not only α-amylase gene expression but also TaS6K1 phosphorylation in wheat embryos .

Thus , a hormonal action of GA turns on the synthesis of α-amylase in wheat germination via activation of the TaTOR-S6K1 signaling pathway .


BACKGROUND : Studies in Arabidopsis show that DELLA genes may differentially affect responses to biotrophic and necrophic pathogens .

A recent report based on the study of DELLA-producing reduced height ( Rht ) genes in wheat and barley also hypothesized that DELLA genes likely increased susceptibility to necrotrophs but increased resistance to biotrophs .

RESULTS : Effects of uzu , a non-GA ( gibberellic acid)-responsive semi-dwarfing gene , on Fusarium crown rot ( FCR ) resistance in barley were investigated .

Fifteen pairs of near isogenic lines for this gene were generated and assessed under two different temperature regimes .

Similar to its impacts on plant height , the semi-dwarfing gene uzu also showed larger effects on FCR severity in the high temperature regime when compared with that in the low temperature regime .

CONCLUSIONS : Results from this study add to the growing evidence showing that the effects of plant height on Fusarium resistances are unlikely related to DELLA genes but due to direct or indirect effects of height difference per se .

The interaction between these two characteristics highlights the importance of understanding relationships between resistance and other traits of agronomic importance as the value of a resistance gene could be compromised if it dramatically affects plant development and morphology .


Cross talk between salicylic acid ( SA ) and jasmonic acid ( JA ) signaling pathways plays an important role in the regulation and fine tuning of induced defenses that are activated upon pathogen or insect attack .

Pharmacological experiments revealed that transcription of JA-responsive marker genes , such as PDF1.2 and VSP2 , is highly sensitive to suppression by SA .

This antagonistic effect of SA on JA signaling was also observed when the JA pathway was biologically activated by necrotrophic pathogens or insect herbivores , and when the SA pathway was triggered by a biotrophic pathogen .

Furthermore , all 18 Arabidopsis ( Arabidopsis thaliana ) accessions tested displayed SA-mediated suppression of JA-responsive gene expression , highlighting the potential significance of this phenomenon in induced plant defenses in nature .

During plant-attacker interactions , the kinetics of SA and JA signaling are highly dynamic .

Mimicking this dynamic response by applying SA and methyl jasmonate ( MeJA ) at different concentrations and time intervals revealed that PDF1.2 transcription is readily suppressed when the SA response was activated at or after the onset of the JA response , and that this SA-JA antagonism is long lasting .

However , when SA was applied more than 30 h prior to the onset of the JA response , the suppressive effect of SA was completely absent .

The window of opportunity of SA to suppress MeJA-induced PDF1.2 transcription coincided with a transient increase in glutathione levels .

The glutathione biosynthesis inhibitor l-buthionine-sulfoximine strongly reduced PDF1.2 suppression by SA , suggesting that SA-mediated redox modulation plays an important role in the SA-mediated attenuation of the JA signaling pathway .


Black pepper ( Piper nigrum L. ) is one of the most popular and oldest spices in the world with culinary uses and various pharmacological properties .

In order to satisfy the growing worldwide demand for black pepper , improved productivity of pepper is highly desirable .

A primary constraint in black pepper production is the non-synchronous nature of flower development and non-uniform fruit ripening within a spike .

The uneven ripening of pepper berries results in a high labour requirement for selective harvesting contributes to low productivity and affects the quality of the pepper products .

In Malaysia , there are a few recommended varieties for black pepper planting , each having some limitations in addition to the useful characteristics .

Therefore , a comparative study of different black pepper varieties will provide a better understanding of the mechanisms regulates fruit development and ripening .

Plant hormones are known to influence the fruit development process and their roles in black pepper flower and fruit development were inferred based on the probe-based gene expression analysis and the quantification of the multiple plant hormones using high-performance liquid chromatography coupled to tandem mass spectrometry ( HPLC-MS/MS ) .

In this study , jasmonic acid and salicylic acid were found to play roles in flowering and fruit setting , whereas auxin , gibberellin and cytokinins are important for fruit growth .

Abscisic acid has positive role in fruit maturation and ripening in the development process .

Distinct pattern of plant hormones related gene expression profiles with the hormones accumulation profiles suggested a complex network of regulation is involved in the signaling process and crosstalk between plant hormones was another layer of regulation in the black pepper fruit development mechanisms .

The current study provides clues to help in elucidating the timing of the action of each specific plant hormone during fruit development and ripening which could be applied to enhance our ability to control the ripening process , leading to improving procedures for the production and post-harvest handling of pepper fruits .


Induced resistance response is a potent and cost effective plant defense against pathogen attack .

The effectiveness and underlying mechanisms of the suppressive ability by Bacillus cereus AR156 to Pseudomonas syringae pv . tomato DC3000 ( Pst DC3000 ) in Arabidopsis has been investigated previously ; however , the strength of induced systemic resistance ( ISR ) activity against Botrytis cinerea remains unknown .

Here , we show that root-drench application of AR156 significantly reduces disease incidence through activation of ISR .

This protection is accompanied with multilayered ISR defense response activated via enhanced accumulation of PR1 protein expression in a timely manner , hydrogen peroxide accumulation and callose deposition , which is significantly more intense in plants with both AR156 pretreatment and B. cinerea inoculation than that in plants with pathogen inoculation only .

Moreover , AR156 can trigger ISR in sid2 - 2 and NahG mutants , but not in jar1 , ein2 and npr1 mutant plants .

Our results indicate that AR156-induced ISR depends on JA/ET-signaling pathway and NPR1 , but not SA .

Also , AR156-treated plants are able to rapidly activate MAPK signaling and FRK1/WRKY53 gene expression , both of which are involved in pathogen associated molecular pattern (PAMP)-triggered immunity ( PTI ) .

The results indicate that AR156 can induce ISR by the JA/ET-signaling pathways in an NPR1-dependent manner and involves multiple PTI components .


The ability to adjust growth and development to the availability of mineral nutrients in the soil is an essential life skill of plants but the underlying signaling pathways are poorly understood .

In Arabidopsis thaliana , shortage of potassium ( K ) induces a number of genes related to the phytohormone jasmonic acid ( JA ) .

Using comparative microarray analysis of wild-type and coi1 - 16 mutant plants , we classified transcriptional responses to K with respect to their dependence on COI1 , a central component of oxylipin signaling .

Expression profiles obtained in a short-term experiment clearly distinguished between COI1-dependent and COI1-independent K-responsive genes , and identified both known and novel targets of JA-COI1-signaling .

During long-term K-deficiency , coi-16 mutants displayed de novo responses covering similar functions as COI1-targets except for defense .

A putative role of JA for enhancing the defense potential of K-deficient plants was further supported by the observation that plants grown on low K were less damaged by thrips than plants grown with sufficient K.


Inducible anti-herbivore defenses in plants are predominantly regulated by jasmonic acid ( JA ) .

On tomato plants , most genotypes of the herbivorous generalist spider mite Tetranychus urticae induce JA defenses and perform poorly on it , whereas the Solanaceae specialist Tetranychus evansi , who suppresses JA defenses , performs well on it .

We asked to which extent these spider mites and the predatory mite Phytoseiulus longipes preying on these spider mites eggs are affected by induced JA-defenses .

By artificially inducing the JA-response of the tomato JA-biosynthesis mutant def-1 using exogenous JA and isoleucine ( Ile ) , we first established the relationship between endogenous JA-Ile-levels and the reproductive performance of spider mites .

For both mite species we observed that they produced more eggs when levels of JA-Ile were low .

Subsequently , we allowed predatory mites to prey on spider mite-eggs derived from wild-type tomato plants , def-1 and JA-Ile-treated def-1 and observed that they preferred , and consumed more , eggs produced on tomato plants with weak JA defenses .

However , predatory mite oviposition was similar across treatments .

Our results show that induced JA-responses negatively affect spider mite performance , but positively affect the survival of their offspring by constraining egg-predation .


During a compatible interaction , the sebacinoid root-associated fungi Piriformospora indica and Sebacina vermifera induce modification of root morphology and enhance shoot growth in Arabidopsis thaliana .

The genomic traits common in these two fungi were investigated and compared with those of other root-associated fungi and saprotrophs .

The transcriptional responses of the two sebacinoid fungi and of Arabidopsis roots to colonization at three different symbiotic stages were analyzed by custom-designed microarrays .

We identified key genomic features characteristic of sebacinoid fungi , such as expansions for gene families involved in hydrolytic activities , carbohydrate-binding and protein-protein interaction .

Additionally , we show that colonization of Arabidopsis correlates with the induction of salicylic acid catabolism and accumulation of jasmonate and glucosinolates ( GSLs ) .

Genes involved in root developmental processes were specifically induced by S. vermifera at later stages during interaction .

Using different Arabidopsis indole-GSLs mutants and measurement of secondary metabolites , we demonstrate the importance of the indolic glucosinolate pathway in the growth restriction of P. indica and S. vermifera and we identify indole-phytoalexins and specifically indole-carboxylic acids derivatives as potential key players in the maintenance of a mutualistic interaction with root endophytes .


Plant growth and development is often regulated by the interaction of environmental factors such as light and various phytohormones .

Arabidopsis FAR-RED INSENSITIVE 219 (FIN219)/JASMONATE RESISTANT 1 ( JAR1 ) participates in phytochrome A-mediated far-red ( FR ) light signaling and interacts with different light signaling regulators .

FIN219/JAR1 is a jasmonic acid (JA)-conjugating enzyme responsible for the formation of JA-isoleucine .

However , how FIN219/JAR1 integrates FR light and JA signaling remains largely unknown .

We used a microarray approach to dissect the effect of fin219 mutation on the interaction of FR light and JA signaling .

The fin219 - 2 mutant was less sensitive than the wild type to various concentrations of methyl jasmonate ( MeJA ) under low and high FR light .

High FR light reduced the sensitivity of Arabidopsis seedlings to MeJA likely through FIN219 .

Intriguingly , in response to MeJA , FIN219 levels showed a negative feedback regulation .

Further microarray assay revealed that FR light could regulate gene expression by FIN219-dependent or -independent pathways .

The expression profiles affected in fin219 - 2 indicated that FIN219/JAR1 plays a critical role in the integration of multiple hormone-related signaling .

In particular , FIN219 regulates a number of transcription factors ( TFs ) , including 94 basic helix-loop-helix ( bHLH ) TFs , in response to FR light and MeJA .

Loss-of-function mutants of some bHLH TFs affected by FIN219 showed altered responses to MeJA in the regulation of hypocotyl and root elongation .

Thus , FIN219/JAR1 is tightly regulated in response to exogenous MeJA .

It also interacts with multiple plant hormones to modulate hypocotyl and root elongation of Arabidopsis seedlings likely by regulating a group of TFs .


Understanding the interactions between drought and acute ozone ( O(3 ) ) stress in terms of signaling molecules and cell death would improve the predictions of plant responses to climate change .

The aim was to investigate whether drought stress influences the responses of plants to acute episodes of O(3 ) exposure .

In this study , the behavior of 84 Mediterranean evergreen Quercus ilex plants was evaluated in terms of cross-talk responses among signaling molecules .

Half of the sample was subjected to drought ( 20 % of the effective daily evapotranspiration , for 15 days ) and was later exposed to an acute O(3 ) exposure ( 200 nL L(-1 ) for 5 h ) .

First , our results indicate that in well-water conditions , O(3 ) induced a signaling pathway specific to O(3)-sensitive behavior .

Second , different trends and consequently different roles of phytohormones and signaling molecules ( ethylene , ET ; abscisic acid , ABA ; salycilic acid , SA and jasmonic acid , JA ) were observed in relation to water stress and O(3 ) .

A spatial and functional correlation between these signaling molecules was observed in modulating O(3)-induced responses in well-watered plants .

In contrast , in drought-stressed plants , these compounds were not involved either in O(3)-induced signaling mechanisms or in leaf senescence ( a response observed in water-stressed plants before the O(3)-exposure ) .

Third , these differences were ascribable to the fact that in drought conditions , most defense processes induced by O(3 ) were compromised and/or altered .

Our results highlight how Q. ilex plants suffering from water deprivation respond differently to an acute O(3 ) episode compared to well-watered plants , and suggest new effect to be considered in plant responses to environmental changes .

This poses the serious question as to whether or not multiple high-magnitude O(3 ) events ( as predicted ) can change these cross-talk responses , thus opening it up possible further investigations .


Ginseng is one of the most important plants in oriental medicine .

The pharmacological effects of this medicinal herb are mostly correlated to the major bioactive triterpene saponin , called ginsenoside .

Due to the long cultivation period of ginseng and increased ginsenoside level in aged root , we need to develop strategies to increase ginseng productivity in cell and tissue culture in a faster way .

Elicitation is already considered to improve the yield of this valuable secondary metabolite ; especially , different types , timings , and durations of elicitation could affect the ginsenoside production and heterogeneity .

Activation of ginsenoside biosynthetic genes and ginsenoside accumulation mediated by elicitor-induced signaling molecules would be helpful for commercial production of individual ginsenosides .

Jasmonic acid is the well-known signaling molecule which mainly involved in ginsenoside accumulation .

Ca(2 + ) spiking and reactive oxygen species , nitric oxide , and ethylene production are other messengers which mediate production of ginsenoside .

This review highlights the elicitation strategies for production of the ginsenoside based on the principle of putative signal transduction pathways .


Salinity is a major environmental factor that constrains soybean yield and grain quality .

Given our past observations using the salt-sensitive soybean ( Glycine max [ L. ] Merr . ) accession C08 on its early responses to salinity and salt-induced transcriptomic modifications , the aim of this study was to assess the lipid profile changes in this cultivar before and after short-term salt stress , and to explore the adaptive mechanisms underpinning lipid homeostasis .

To this end , lipid profiling and proteomic analyses were performed on the leaves of soybean seedlings subjected to salt treatment for 0 , 0.5 , 1 , and 2 h. Our results revealed that short-term salt stress caused dynamic lipid alterations resulting in recycling for both galactolipids and phospholipids .

A comprehensive understanding of membrane lipid adaption following salt treatment was achieved by combining time-dependent lipidomic and proteomic data .

Proteins involved in phosphoinositide synthesis and turnover were upregulated at the onset of salt treatment .

Salinity-induced lipid recycling was shown to enhance jasmonic acid and phosphatidylinositol biosyntheses .

Our study demonstrated that salt stress resulted in a remodeling of membrane lipid composition and an alteration in membrane lipids associated with lipid signaling and metabolism in C08 leaves .


BACKGROUND : Plant genes that provide a different response to a similar dehydration stress illustrate the concept of transcriptional ' dehydration stress memory ' .

Pre-exposing a plant to a biotic stress or a stress-signaling hormone may increase transcription from response genes in a future stress , a phenomenon known as ' gene priming ' .

Although known that primed transcription is preceded by accumulation of H3K4me3 marks at primed genes , what mechanism provides for their appearance before the transcription was unclear .

How augmented transcription is achieved , whether/how the two memory phenomena are connected at the transcriptional level , and whether similar molecular and/or epigenetic mechanisms regulate them are fundamental questions about the molecular mechanisms regulating gene expression .

RESULTS : Although the stress hormone jasmonic acid ( JA ) was unable to induce transcription of tested dehydration stress response genes , it strongly potentiated transcription from specific ABA-dependent ' memory ' genes .

We elucidate the molecular mechanism causing their priming , demonstrate that stalled RNA polymerase II and H3K4me3 accumulate as epigenetic marks at the JA-primed ABA-dependent genes before actual transcription , and describe how these events occur mechanistically .

The transcription factor MYC2 binds to the genes in response to both dehydration stress and to JA and determines the specificity of the priming .

The MEDIATOR subunit MED25 links JA-priming with dehydration stress response pathways at the transcriptional level .

Possible biological relevance of primed enhanced transcription from the specific memory genes is discussed .

CONCLUSIONS : The biotic stress hormone JA potentiated transcription from a specific subset of ABA-response genes , revealing a novel aspect of the JA- and ABA-signaling pathways ' interactions .

H3K4me3 functions as an epigenetic mark at JA-primed dehydration stress response genes before transcription .

We emphasize that histone and epigenetic marks are not synonymous and argue that distinguishing between them is important for understanding the role of chromatin marks in genes ' transcriptional performance .

JA-priming , specifically of dehydration stress memory genes encoding cell/membrane protective functions , suggests it is an adaptational response to two different environmental stresses .


Mitogen-activated protein kinases ( MAPKs ) play an important role in defense responses to biotic and abiotic stresses .

In order to investigate the role of SlMAPK3 in tomato plant resistance to Botrytis cinerea , two lines of slmapk3 mutants and wild-type ( WT ) tomato plants were used .

The results showed that slmapk3 mutants were more susceptible to B. cinerea and that knockout of SlMAPK3 reduced the activities of defense enzymes and enhanced the accumulation of reactive oxygen species ( ROS ) .

Furthermore , we detected the expressions of salicylic acid ( SA ) and jasmonic acid ( JA ) signaling-related genes and found that knockout of SlMAPK3 enhanced the expressions of SlPR1 , SlPAD4 and SlEDS1 , whereas reduced the expressions of SlLoxC , SlPI I and SlPI II and enhanced the expressions of SlJAZ1 and SlMYC2 .

We postulate that SlMAPK3 plays a positive role in tomato plant resistance to B. cinerea through regulating ROS accumulation and SA and JA defense signaling pathways .


We analyzed the susceptibility of Arabidopsis mutants with defects in salicylic acid ( SA ) and jasmonic acid (JA)/ethylene ( ET ) signaling to infection by Cauliflower mosaic virus ( CaMV ) .

Mutants cpr1 - 1 and cpr5 - 2 , in which SA-dependent defense signaling is activated constitutively , were substantially more resistant than the wild type to systemic infection , implicating SA signaling in defense against CaMV .

However , SA-deficient NahG , sid2 - 2 , eds5 - 1 , and pad4 - 1 did not show enhanced susceptibility .

A cpr5 eds5 double mutant also was resistant , suggesting that resistance in cpr5 may function partially independently of SA .

Treatment of cpr5 and cpr5 eds5 , but not cpr1 , with salicyl-hydroxamic acid , an inhibitor of alternative oxidase , partially restored susceptibility to wild-type levels .

Mutants etr1 - 1 , etr1 - 3 , and ein2 - 1 , and two mutants with lesions in ET/JA-mediated defense , eds4 and eds8 , also showed reduced virus susceptibility , demonstrating that ET-dependent responses also play a role in susceptibility .

We used a green fluorescent protein (GFP)-expressing CaMV recombinant to monitor virus movement .

In mutants with reduced susceptibility , cpr1 - 1 , cpr5 - 2 , and etr1 - 1 , CaMV-GFP formed local lesions similar to the wild type , but systemic spread was almost completely absent in cpr1 and cpr5 and was substantially reduced in etr1 - 1 .

Thus , mutations with enhanced systemic acquired resistance or compromised ET signaling show diminished long-distance virus movement .


The formation of amylase isozymes in germinating rice ( Oryza sativa ) seeds was studied by isoelectric focusing on polyacrylamide gel disc electrophoresis .

Time sequence comparisons of the amylase zymogram were made between extracts from gibberellic acid-treated embryoless and embryo-attached half-endosperm of rice seeds .

In both cases , 4 major and 9 to 10 minor isozyme bands were detectable at the maximal stage of the enzyme induction .

However , in the embryo-attached half-seeds , bands started to diminish after the 5th day of incubation , in agreement with the results of time sequence analyses of enzyme activities .

Nearly identical patterns of amylase isozyme bands on a polyacrylamide gel disc electrophoresis in combination with isoelectric focusing indicate the intrinsic role of gibberellic acid in the starch breakdown in germinating rice seeds .

We tentatively assign the newly synthesized enzymes to be alpha-amylases based on experimental results concerning the lability of the preparation on a prolonged treatment at pH 3.3 and the stability on heat treatment for 15 minutes at 70 C.


A general prediction of the specialist/generalist paradigm indicates that plant responses to insect herbivores may depend on the degree of ecological specialization of the insect attacker .

However , results from a single greenhouse experiment evaluating the responses of the model plant Arabidopsis thaliana to three specialist ( Plutella xylostella , Pieris rapae , and Brevicoryne brassicae ) and three generalist ( Trichoplusia ni , Spodoptera exigua , and Myzus persicae ) insect species did not support the previous prediction .

Using an ecological genomic approach , we assessed plant responses in terms of herbivore-induced changes in genome-wide gene expression , defense-related pathways , and concentrations of glucosinolates ( i.e. , secondary metabolites that are ubiquitously present in cruciferous plants ) .

Our results showed that plant responses were not influenced by the degree of specialization of insect herbivores .

In contrast , responses were more strongly shaped by insect taxa ( i.e. , aphid vs. lepidopteran species ) , likely due to their different feeding modes .

Interestingly , similar patterns of plant responses were induced by the same insect herbivore species in terms of defense signaling ( jasmonic acid pathway ) , aliphatic glucosinolate metabolism ( at both the gene expression and phenotypic levels ) and genome-wide responses .

Furthermore , plant responses to insect herbivores belonging to the same taxon ( i.e. , four lepidopteran species ) were not explained by herbivore specialization or phylogenetic history .

Overall , this study suggests that different feeding modes of insect taxa as well as herbivore-specific plant responses , which may result from distinct ecological/evolutionary interactions between A. thaliana ( or a close relative ) and each of the lepidopteran species , may explain why observed responses deviate from those predicted by the specialist/generalist paradigm .


Transcriptional regulation plays a central role in plant hormone signaling .

At the core of transcriptional regulation is the Mediator , an evolutionarily conserved , multisubunit complex that serves as a bridge between gene-specific transcription factors and the RNA polymerase machinery to regulate transcription .

Here , we report the action mechanisms of the MEDIATOR25 ( MED25 ) subunit of the Arabidopsis thaliana Mediator in regulating jasmonate- and abscisic acid (ABA)-triggered gene transcription .

We show that during jasmonate signaling , MED25 physically associates with the basic helix-loop-helix transcription factor MYC2 in promoter regions of MYC2 target genes and exerts a positive effect on MYC2-regulated gene transcription .

We also show that MED25 physically associates with the basic Leu zipper transcription factor ABA-INSENSITIVE5 ( ABI5 ) in promoter regions of ABI5 target genes and shows a negative effect on ABI5-regulated gene transcription .

Our results reveal that underlying the distinct effects of MED25 on jasmonate and ABA signaling , the interaction mechanisms of MED25 with MYC2 and ABI5 are different .

These results highlight that the MED25 subunit of the Arabidopsis Mediator regulates a wide range of signaling pathways through selectively interacting with specific transcription factors .


Plants subjected to drought and saline stress conditions suffer from tissue dehydration .

Such dehydration is caused by the imbalance between root water uptake by roots and water loss by transpiration .

Therefore , determination of root hydraulic properties is crucial to understand plant water balance .

Root hydraulic conductivity ( L ) can be used to estimate root water transport capacity .

L depends on root architecture ( length and diameter of the root and proliferation of secondary roots ) , radial water transport pathway ( root xylem vessels , plasmodesmata , apoplastic space , caspary bands ) , and on intrinsic membrane permeability to water ( aquaporins , water membrane protein channels ) .

Different methods have been developed to measure L , such as Pressure Chamber , Free Exudation , High-Pressure Flowmeter ( HPFM ) , and Root Pressure Probe ( RPP ) .

In this chapter , we will focus on Pressure Chamber , Free Exudation , and HPFM methods which have been used to determine the effect of jasmonates ( JA ) on root hydraulic conductivity .


Plant growth and development are controlled by nine structurally distinct small molecules termed phytohormones .

Over the last 20 years , the molecular basis of their signal transduction , from receptors to transcription factors , has been dissected using mainly Arabidopsis thaliana and rice as model systems .

Phytohormones can be broadly classified into two distinct groups on the basis of whether the subcellular localization of their receptors is in the cytoplasm or nucleus , and hence soluble , or membrane-bound , and hence insoluble .

Soluble receptors , which control the responses to auxin , jasmonates , gibberellins , strigolactones and salicylic acid , signal either directly or indirectly via the destruction of regulatory proteins .

Responses to abscisic acid are primarily mediated by soluble receptors that indirectly regulate the phosphorylation of targeted proteins .

Insoluble receptors , which control the responses to cytokinins , brassinosteroids and ethylene , transduce their signal through protein phosphorylation .

This chapter provides a comparison of the different components of these signalling systems , and discusses the similarities and differences between them .


The volatile metabolite methyl jasmonate ( MeJA ) plays an important role in intra- and interplant communication and is involved in diverse biological processes .

In this study , we report the cloning and functional characterization of a S-adenosyl-l-methionine : jasmonic acid carboxyl methyltransferase ( JMT ) from Fragaria vesca and Fragaria × ananassa .

Biochemical assays and comprehensive transcript analyses showed that JMT has been erroneously annotated as gene fusion with a carboxyl methyltransferase ( CMT ) ( gene15184 ) in the first published genome sequence of F. vesca .

Recombinant FvJMT catalyzed the formation of MeJA with KM value of 22.3μM while FvCMT and the fusion protein were almost inactive .

Activity of JMT with benzoic acid and salicylic acid as substrates was less than 1.5 % of that with JA .

Leucine at position 245 , an amino acid missing in other JMT sequences is essential for activity of FvJMT .

In accordance with MeJA levels , JMT transcript levels decreased steadily during strawberry fruit ripening , as did the expression levels of JA biosynthesis and regulatory genes .

It appears that CMT has originated by a recent duplication of JMT and lost its enzymatic activity toward JA .

In the newest version of the strawberry genome sequence ( June 2014 ) CMT and JMT are annotated as separate genes in accordance with differential temporal and spatial expression patterns of both genes in Fragaria sp. In conclusion , MeJA , the inactive derivative of JA , is probably involved in early steps of fruit development by modulating the levels of the active plant hormone JA .


Ramularia leaf spot disease ( RLS ) , caused by the ascomycete fungus Ramularia collo-cygni , has emerged as a major economic disease of barley .

No substantial resistance has been identified , so far , among barley genotypes and , based on the epidemiology of the disease , a quantitative genetic determinacy of RLS has been suggested .

The relative contributions of barley and R. collo-cygni genetics to disease infection and epidemiology are practically unknown .

Here , we present an integrated genome-wide analysis of host and pathogen transcriptome landscapes identified in a sensitive barley cultivar following infection by an aggressive R. collo-cygni isolate .

We compared transcriptional responses in the infected and noninfected leaf samples in order to identify which molecular events are associated with RLS symptom development .

We found a large proportion of R. collo-cygni genes to be expressed in planta and that many were also closely associated with the infection stage .

The transition from surface to apoplastic colonization was associated with downregulation of cell wall-degrading genes and upregulation of nutrient uptake and resistance to oxidative stresses .

Interestingly , the production of secondary metabolites was dynamically regulated within the fungus , indicating that R. collo-cygni produces a diverse panel of toxic compounds according to the infection stage .

A defense response against R. collo-cygni was identified in barley at the early , asymptomatic infection and colonization stages .

We found activation of ethylene signaling , jasmonic acid signaling , and phenylpropanoid and flavonoid pathways to be highly induced , indicative of a classical response to necrotrophic pathogens .

Disease development was found to be associated with gene expression patterns similar to those found at the onset of leaf senescence , when nutrients , possibly , are used by the infecting fungus .

These analyses , combining both barley and R. collo-cygni transcript profiles , demonstrate the activation of complex transcriptional programs in both organisms .


Seed germination is antagonistically controlled by the phytohormones gibberellic acid ( GA ) and abscisic acid ( ABA ) .

GA promotes seed germination by enhancing the proteasome-mediated destruction of RGL2 ( for RGA-LIKE2 ) , a key DELLA factor repressing germination .

By contrast , ABA blocks germination by inducing ABI5 ( for ABA-INSENSITIVE5 ) , a basic domain/leucine zipper transcription factor repressing germination .

Decreased GA synthesis leads to an increase in endogenous ABA levels through a stabilized RGL2 , a process that may involve XERICO , a RING-H2 zinc finger factor promoting ABA synthesis .

In turn , increased endogenous ABA synthesis is necessary to elevate not only ABI5 RNA and protein levels but also , critically , those of RGL2 .

Increased ABI5 protein is ultimately responsible for preventing seed germination when GA levels are reduced .

However , overexpression of ABI5 was not sufficient to repress germination , as ABI5 activity requires phosphorylation .

The endogenous ABI5 phosphorylation and inhibition of germination could be recapitulated by the addition of a SnRK2 protein kinase to the ABI5 overexpression line .

In sleepy1 mutant seeds , RGL2 overaccumulates ; germination of these seeds can occur under conditions that produce low ABI5 expression .

These data support the notion that ABI5 acts as the final common repressor of germination in response to changes in ABA and GA levels .


BACKGROUND : Postharvest fruit conservation relies on low temperatures and manipulations of hormone metabolism to maintain sensory properties .

Peaches are susceptible to chilling injuries , such as ' woolliness ' that is caused by juice loss leading to a ' wooly ' fruit texture .

Application of gibberellic acid at the initial stages of pit hardening impairs woolliness incidence , however the mechanisms controlling the response remain unknown .

We have employed genome wide transcriptional profiling to investigate the effects of gibberellic acid application and cold storage on harvested peaches .

RESULTS : Approximately half of the investigated genes exhibited significant differential expression in response to the treatments .

Cellular and developmental process gene ontologies were overrepresented among the differentially regulated genes , whereas sequences in cell death and immune response categories were underrepresented .

Gene set enrichment demonstrated a predominant role of cold storage in repressing the transcription of genes associated to cell wall metabolism .

In contrast , genes involved in hormone responses exhibited a more complex transcriptional response , indicating an extensive network of crosstalk between hormone signaling and low temperatures .

Time course transcriptional analyses demonstrate the large contribution of gene expression regulation on the biochemical changes leading to woolliness in peach .

CONCLUSION : Overall , our results provide insights on the mechanisms controlling the complex phenotypes associated to postharvest textural changes in peach and suggest that hormone mediated reprogramming previous to pit hardening affects the onset of chilling injuries .