BAPID suppresses the inhibition of BRM on Di19‐PR module in response to drought.

SUMMARY: Drought is one of the most important abiotic stresses, and seriously threatens plant development and productivity. Increasing evidence indicates that chromatin remodelers are pivotal for plant drought response. However, molecular mechanisms of chromatin remodelers‐mediated plant drought responses remain obscure. In this study, we found a novel interactor of BRM called BRM‐associated protein involved in drought response (BAPID), which interacted with SWI/SNF chromatin remodeler BRM and drought‐induced transcription factor Di19. Our findings demonstrated that BAPID acted as a positive drought regulator since drought tolerance was increased in BAPID‐overexpressing plants, but decreased in BAPID‐deficient plants, and physically bound to PR1, PR2, and PR5 promoters to mediate expression of PR genes to defend against dehydration stress. Genetic approaches demonstrated that BRM acted epistatically to BAPID and Di19 in drought response in Arabidopsis. Furthermore, the BAPID protein‐inhibited interaction between BRM and Di19, and suppressed the inhibition of BRM on the Di19‐PR module by mediating the H3K27me3 deposition at PR loci, thus changing nucleosome accessibility of Di19 and activating transcription of PR genes in response to drought. Our results shed light on the molecular mechanism whereby the BAPID‐BRM‐Di19‐PRs pathway mediates plant drought responses. We provide data improving our understanding of chromatin remodeler‐mediated plant drought regulation network. Significance Statement: Drought is an enormous threat to plant growth and reproduction, but the roles of chromatin remodelers in mediating plant drought responses remain indistinct so far. In this study, we illuminated the molecular mechanism of the BAPID‐BRM‐Di19‐PRs pathway in drought response in Arabidopsis, promoting our cognition on chromatin remodeler‐mediated plant drought regulation network. [ABSTRACT FROM AUTHOR]