Phenotypes of AtRGGA knockout and overexpressing plants. A, Representative 4-week-old plants of Col-0, rgga, and 35S::FLAG-RGGA genotypes grown in control conditions or after 7-d NaCl (300 mm) or drought treatment. B, Pro concentrations in Col-0, rgga, and 35S::FLAG-RGGA plants treated as described in A. Asterisks indicate statistically significant differences assessed by Student’s t test (P < 0.01).