The osphyB-2 mutant exhibited an early senescence phenotype during DIS. (A) WT and osphyB-2 whole plants were grown for 1 month under LD (14-h light/day) conditions and then were transferred to darkness at 28 °C for 10 days (10 DDI); (B) The color change that occurs in leaf segments of WT, osphyB-2, and osphyA-3 during DIS; (C,D) The changes of total Chl level (C) and ion leakage rate (D) in the leaf segments of WT and osphyB-2 during DIS. They were incubated on 3 mM MES (pH 5.8) buffer with the abaxial side up at 28 °C in darkness. Mean and SD values in (C,D) were obtained from at least five biological replicates. Asterisks indicate significant difference between WT and osphyB-2 (Student’s t-test p values, *p < 0.05; **p < 0.01). NS, not significant; DDI, day(s) of dark incubation.