Expression of ABA- and stress-responsive genes. Expression of ABA- and stress-responsive genes was assayed by qRT-PCR in seedlings of Col-0, 35S:RHA2a, rha2a, 35S:RHA2b, rha2b-1, and rha2a rha2b-1. Two-week-old seedlings were treated with 100 μm ABA for 0, 3, and 6 h. Data shown are means ± sd of three independent experiments. Asterisks indicate significant differences from the corresponding wild-type values determined by Student’s t test (* 0.01 ≤ P < 0.05, ** P < 0.01).