HPR1 protein content and growth phenotype of complemented hpr1 lines. A, HPR1 protein level analysis in rosette leaves of Col-0 (wild-type [WT]), hpr1-1, and HPR1-, HPR1-T335A-, and HPR1-T335D-complemented hpr1 transgenic lines. Soluble proteins were extracted from rosette leaves of 4-week-old short-day, ambient air-grown plants, and HPR1 protein levels were revealed by immunoblotting using anti-HPR1 antibodies. The large subunit of Rubisco stained with Coomassie blue was used as a loading control. B, Growth phenotype of 4-week-old short-day, ambient air-grown Col-0 (wild-type), hpr1-1, and HPR1-, HPR1-T335A-, and HPR1-T335D-complemented hpr1 plants. C, Rosette diameter of all plant lines grown under the same conditions as in B. Values are means ± sd (n = 5) of three biological repetitions. The asterisks indicate significant differences compared to Col-0 (*P < 0.05, **P < 0.01, and ***P < 0.001).