Expression of salicylic acid biosynthesis genes and salicylic acid level in roots. Relative transcript levels of the TaICSs (A,B) and TaPALs (C–E), and salicylic acid level (F) in roots at 1, 7 and 14 days after waterlogging (DAWL). Transcript levels of the TaICSs and TaPALs were determined using Ta18SrRNA as the reference gene and expressed relative to the transcript levels of TaICS1 and TaPAL4 in control roots at 1 DAWL, respectively, which were arbitrarily set a value of 1. Data are means of three independent biological replicates ± SE. Asterisks show significant difference in transcript levels between the control (non-waterlogged) and waterlogged samples within waterlogging duration (one-way ANOVA; p < 0.05, Fisher’s LSD test).