Suppressing an auxin efflux transporter enhances rice adaptation to temperate habitats
Yanchun Cui, Lifang Huang, Peng Liu, Xiaodong Wang, Bi Wu, Yongjun Tan, Xuan Huang, Xiaojie Hu, Zhankun He, Yuqi Xia, Zhansheng Li, Wenli Zhang, Wenbang Tang, Yongzhong Xing, Caiyan Chen, Donghai Mao
Abstract
Rice (Oryza sativa L.), a chilling-sensitive staple crop originating from tropical and subtropical Asia, can be cultivated in temperate regions through the introduction of chilling tolerance traits. However, the molecular mechanisms underlying this adaptation remain largely unknown. Herein, we show that HAN2, a quantitative trait locus, confers chilling tolerance in temperate japonica rice. HAN2 encodes an auxin efflux transporter (OsABCB5) and negatively regulates chilling tolerance, potentially via auxin-mediated signaling pathway. During rice domestication, HAN2 has undergone selective divergence between the indica and temperate japonica subspecies. In temperate japonica rice, the insertion of a Copia long terminal repeat retrotransposon downstream of HAN2 reduces its expression, thereby enhancing chilling tolerance and facilitating adaptation to temperate climates. Introgression of the temperate japonica HAN2 allele into indica rice significantly improves chilling tolerance at both seedling and booting stages. These findings advance our understanding of rice northward expansion and provide a valuable genetic resource for improving yield stability under chilling stress. The mechanism through which auxin regulates chilling tolerance remains unclear. Here, the authors discover a negative regulator of chilling tolerance in japonica rice, which encodes an ABCB transporter with auxin efflux function, and show its potential to increase indica rice chilling tolerance.