摘要The plant hormone abscisic acid(ABA)is crucial for plant seed germination and abiotic stress tolerance.However,the association between ABA sensitivity and plant abiotic stress tolerance remains largely unknown.In this study,436 rice accessions were assessed for their sensitivity to ABA during seed germination.The considerable diversity in ABA sen-sitivity among rice germplasm accessions was pri-marily reflected by the differentiation between the Xian(indica)and Geng(japonica)subspecies and between the upland-Geng and lowland-Geng eco-types.The upland-Geng accessions were most sen-sitive to ABA.Genome-wide association analyses identified four major quantitative trait loci containing 21 candidate genes associated with ABA sensitivity of which a basic helix-loop-helix transcription factor gene,OsbHLH38,was the most important for ABA sensitivity.Comprehensive functional analyses using knockout and overexpression transgenic lines re-vealed that OsbHLH38 expression was responsive to multiple abiotic stresses.Overexpression of OsbHLH38 increased seedling salt tolerance,while knockout of OsbHLH38 increased sensitivity to salt stress.A salt-responsive transcription factor,Os-DREB2A,interacted with OsbHLH38 and was directly regulated by OsbHLH38.Moreover,OsbHLH38 af-fected rice abiotic stress tolerance by mediating the expression of a large set of transporter genes of phytohormones,transcription factor genes,and many downstream genes with diverse functions,in-cluding photosynthesis,redox homeostasis,and abiotic stress responsiveness.These results dem-onstrated that OsbHLH38 is a key regulator in plant abiotic stress tolerance.