摘要Rice ratooning,the fast outgrowth of dormant buds on stubble,is an important cropping practice in rice production.However,the low ratooning ability(RA)of most rice varieties restricts the application of this cost-efficient system,and the genetic basis of RA remains unknown.In this study,we dissected the genetic architecture of RA by a genome-wide association study in a natural rice population.Rice ratooning ability 3(RRA3),encoding a hitherto not characterized nucleoredoxin involved in reduction of disulfide bonds,was identified as the causal gene of a major locus controlling RA.Overexpression of RRA3 in rice significantly accelerated leaf senescence and reduced RA,whereas knockout of RRA3 significantly delayed leaf senes-cence and increased RA and ratoon yield.We demonstrated that RRA3 interacts with Oryza sativa histidine kinase 4(OHK4),a cytokinin receptor,and inhibits the dimerization of OHK4 through disulfide bond reduc-tion.This inhibition ultimately led to decreased cytokinin signaling and reduced RA.In addition,variations in the RRA3 promoter were identified to be associated with RA.Introgression of a superior haplotype with weak expression of RRA3 into the elite rice variety Guichao 2 significantly increased RA and ratoon yield by 23.8％.Collectively,this study not only uncovers an undocumented regulatory mechanism of cytokinin signaling through de-dimerization of a histidine kinase receptor-but also provides an eximious gene with promising value for ratoon rice breeding.