sentence: Arabidopsis ( Arabidopsis thaliana ) ecotype Col-0 ( WT ) , XRN4 T-DNA insertion lines ( xrn4 – 5 ( 59 ) and SALK_014209 ( 60 ) ) , xrn2 – 1xrn3 – 3 ( 60 ) and upf1 – 1 ( 61 ) in the Col-0 background were used .