OsMAPK6 phosphorylates a zinc finger protein OsLIC to promote downstream OsWRKY30 for rice resistance to bacterial blight and leaf streak

Rice OsLIC encoding a CCCH zinc finger transcription factor plays an important role in immunity.However,the immune signaling pathways that OsLIC-involved and the underlying mechanisms that OsLIC-conferred resistance against pathogens are largely unclear.Here,we show that OsLIC,as a substrate for Os MAPK6,negatively regulates resistance to Xanthomonas oryzae pv.oryzae(Xoo)and X.oryzae pv.oryzicola(Xoc)by directly suppressing OsWRKY30 transcription.Biochemical assays showed that OsLIC bound to OsWRKY30 promoter and suppressed its transcription.Genetic assays confirmed that the osilc knockout mutants and OsWRKY30-overexpressing plants exhibited enhanced resistance to Xoo and Xoc,knocking out OsWRKY30 in the oslic mutants attenuated the resistance against bacterial pathogens.Os MAPK6 physically interacted with and phosphorylated OsLIC leading to decreased OsLIC DNA-binding activity,therefore,overexpression of OsLIC partially suppressed Os MAPK6-mediated rice resistance.In addition,both Os MAPK6-phosphorylated activation of OsLIC and phosphorylation-mimic OsLIC_(5D) had reduced DNA-binding activity towards OsWRKY30 promoter,thereby promoting OsWRKY30 transcription.Collectively,these results reveal that Os MAPK6-mediated phosphorylation of OsLIC positively regulates rice resistance to Xoo and Xoc by modulating OsWRKY30 transcription,suggesting that Os MAPK6-OsLIC-OsWRKY30 module is an immune signaling pathway in response to the bacterial pathogens.