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