Identification of OsMYC2-regulated senescence-associated genes in rice.

The jasmonic acid (JA)-responsive transcription factor OsMYC2 acts as a positive regulator of leaf senescence by direct regulation of some senescence-associated genes in rice. OsMYC2, a transcription factor (TF), acts as a positive regulator of jasmonic acid (JA) signaling involved in development and defense in rice. Here, we report that OsMYC2 plays an important role in leaf senescence under dark-induced senescence (DIS) conditions. Overexpression of OsMYC2 significantly promoted leaf senescence, indicated by reduction of chlorophyll content under DIS conditions in rice. Leaf senescence under the DIS conditions was negatively regulated by OsJAZ8, a rice jasmonate ZIM-domain protein involved in the JA signaling pathway. OsMYC2 upregulated the expression of some senescence-associated genes (SAGs) and selectively bound to the G-box/G-box-like motifs in the promoters of some SAGs in vivo. These results suggest that OsMYC2 acts as a positive regulator of leaf senescence by direct- or indirect-regulation of SAGs in rice.