Immune Mechanism of Ethylicin-Induced Resistance to Xanthomonas oryzae pv. oryzae in Rice

Ethylicin (ET) was reported to be promising in the control of rice bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo). The detailed mechanism for this process remains unknown. Disclosed here is an in-depth study on the action mode of ET to Xoo. Through plant physiological and biochemical analysis, it was found that ET could inhibit the proliferation of Xoo by increasing the content of defense enzymes and chlorophyll in rice (Oryza sativa ssp. Japonica cv. Nipponbare). Label-free quantitative proteomic analysis showed that ET affected the rice abscisic acid (ABA) signal pathway and made the critical differential calcium-dependent protein kinase 24 (OsCPK24) more active. In addition, the biological function of OsCPK24 as a mediator for rice resistance to Xoo was determined through the anti-Xoo phenotypic test of OsCPK24 transgenic rice and the affinity analysis of the OsCPK24 recombinant protein in vitro and ET. This study revealed the molecular mechanism of ET-induced resistance to Xoo in rice via OsCPK24, which provided a basis for the development of new bactericides based on the OsCPK24 protein.