FIGURE 5.

Influence of K supply on the expression of genes involved in ABA biosynthesis and degradation in flag leaves of barley under drought stress. Relative mRNA levels of (A) 9-cis- epoxy-carotenoid dioxygenase (HvNCED2) and (B) ABA-8′-hydroxylase 1 (HvABA-8′-OH1) in flag leaves of the lines HPR and LPR. Plants were pre-cultured under sufficient water supply (control) or water limitation (stress) and under low or high K supply. Flag leaves from 12 weeks-old plants were harvested 12 days after imposing drought stress. Bars indicate mean ± SD. Different letters denote significant differences according to three-way ANOVA and Tukey’s test (p < 0.05; n = 4–6). Ubi E2-17 (ubiquitin-conjugating enzyme) was used as reference gene.