OsPHR2 modulates phosphate starvation-induced jasmonic acid response and resistance to Xanthomonas oryzae pv. oryzae

Phosphate (Pi) and jasmonic acid (JA) play critical roles in plant growth and development. In particular, crosstalk between JA and Pi starvation signaling has been reported to mediate insect herbivory resistance in dicot plants. However, its roles and mechanism in monocot-bacterial defense systems remain obscure. Here, we report that Pi starvation in rice activates the JA signaling and enhances resistance to Xanthomonas oryzae pv. oryzae (Xoo) infection. The direct regulation of OsPHR2 on the OsMYC2 promoter was confirmed by yeast one-hybrid, electrophoretic mobility shift, dual-luciferase, and chromatin immunoprecipitation assays. Molecular analyses and infection studies using OsPHR2-Ov1 and phr2 mutants further demonstrated that OsPHR2 enhances JA response and antibacterial resistance via transcriptional regulation of OsMYC2 expression, indicating a positive role of OsPHR2-OsMYC2 crosstalk in modulating the JA response and Xoo infection. Genetic analysis and infection assays using myc2 mutants revealed that Pi starvation-induced JA signaling activation and consequent Xoo resistance depends on the regulation of OsMYC2. Together, these results reveal a clear interlink between Pi starvation signaling and the JA signaling in monocot plants, and provide new insight into how plants balance growth and defense by integrating nutrient deficiency and phytohormone signaling.