Expression of ABA biosynthesis and drought signaling-related genes in the indicated genotypes. Relative expression of a AtABA3, b AtABI2, c AtABA2, d AtDREB1, e AtDREB2, f AtAPX1, and g AtNCED3. The experiments were repeated at least three times. Error bars represent ±SE. Significance differences are represented by asterisks (Student t-test). * represents p < 0.05, ** represents p < 0.01 and *** represents p ≤ 0.001.