Fig. 7

OsbHLH079 delays ABA-induced leaf senescence in rice. A Expression of OsbHLH079 in response to senescence-promoting phytohormones. WT seedlings were grown on half-strength Murashige and Skoog (MS) solid medium (pH 5.7) under constant light conditions at 30 °C for 10 days. Seedlings were then transferred to half-strength MS liquid medium supplemented with 100 µM ABA, 10 mM ACC, 100 µM MeJA, or 100 µM SA. Leaves were harvested at 3 and 6 h after treatments, and their total RNAs were used for RT-qPCR analysis, with expression levels of OsbHLH079 normalized to those of GAPDH. Means and standard deviations were obtained from four biological replicates consisting of approximately three leaves per sample. Statistically significant differences compared to the mock-treated samples are marked by asterisks, as determined by the two-tailed Student’s t-test (***P < 0.001). ABA, abscisic acid; ACC, 1-aminocyclopropane-1-carboxylic acid; MeJA, methyl jasmonate; NS, not significant; SA, salicylic acid. B-D Leaf color (B), total chlorophyll content (C), and ion leakage rate (D) of WT, osbhlh079-D, OsbHLH079-OE, osbhlh079-1, and osbhlh079-2 under ABA-induced senescence conditions. Flag leaf discs were collected at the heading stage from the rice plants grown under natural field conditions. The leaf discs were then treated with a 3 mM MES buffer (pH 5.8) containing 50 µM ABA for the indicated time periods under continuous light conditions at 30 °C. Data presented in (C, D) represent the average ± SD of four biological replicates [around 10 mg of leaf discs per replicate in (C) and approximately five leaf discs per replicate in (D)]. Asterisks indicate significantly different values according to Student’s t-test (**P < 0.01 and ***P < 0.001). ABA, abscisic acid; Chl, chlorophyll; DT, day(s) of treatment; FW, fresh weight; NS, not significant. These experiments were performed twice with similar results