OsMYB1 antagonizes OsSPL14 to mediate rice resistance to brown planthopper and Xanthomonas oryzae pv. oryzae.

OsMYB1 negatively mediates rice resistance to brown planthopper and rice blight. Additionally, OsMYB1 interacts with OsSPL14 and antagonizes its function by oppositely regulating downstream resistance-related genes. In their natural habitats, plants are concurrently attacked by different biotic factors. Xanthomonas oryzae pv. oryzae (Xoo) is a pathogen that severely deteriorates rice yield and quality, and brown planthopper (BPH; Nilaparvata lugens) is a rice specific insect pest with the damage topping other pathogens. Although genes for respective resistance to BPH and Xoo have been widely reported, few studies pay attention to simultaneous resistance to both. In this study, we identified a MYB transcription factor, OsMYB1, which exhibited diverse transcriptional regulatory capabilities and a negative regulatory role in resistance to both BPH and Xoo. Biochemical and genetic analysis proved OsMYB1 to be a TF that could interact with OsSPL14, a positive regulator of rice resistance to Xoo. OsSPL14 mutants showed increased sensitivity to BPH, suggesting that OsSPL14 is contrary to OsMYB1 in regulating rice resistance to these two biotic stresses. Consistently, OsMYB1 and OsSPL14 displayed opposite functions in regulating defense-related genes. OsMYB1 can form transcription regulation complexes with repressor OsJAZs instead of co-repressor TOPLESS to possibly realize its transcriptional repression function. Taken together, we concluded that two interacting TFs in rice, OsMYB1 and OsSPL14, played antagonistic roles in regulating resistance to BPH and Xoo.