Figure 3.

Functional inactivation of ZmABH4 by CRISPR/Cas9 alters the ratio of PA to ABA and water relations in maize. A–D, Content of ABA, and the ratio of the first stable product of ABA 8′-hydroxylation, PA, relative to ABA in fully developed leaves measured (A and B) in leaves of well-watered plants (n = 21–25 plants), (C and D) in leaves of plants grown under either well-watered conditions, mild drought stress, or mild stress with subsequent rewatering (n = 4–5 plants, shown are means ± SE and individual data points). E, Assimilation rate (A_N) over stomatal conductance (g_s) of well-watered plants (n = 16–17 plants, mean ± SE). The percentage decrease in the mean value of the mutant relative to its WT is shown for A_N and g_s. F, Intrinsic water use efficiency (iWUE) calculated from data shown in E (n = 16–17 plants). G, WUE_plant of plants grown under progressive drought to determine the dry weights plants are capable of attaining with a given amount of water, n = 14–22 plants. H, Carbon isotope discrimination of kernels (Δ¹³C_Kernel), n = 18–22 plants. Bars show means ± SE. Boxplots with center line, median; box limits, upper and lower quartiles; whiskers, 1.5× interquartile range. One-sided Student’s t test between the abh4 mutant and respective WT with ***P < 0.001, **P < 0.01, *P < 0.05. I, Phenotypes of well-watered mutant and WT plants.