Natural variation in WHITE-CORE RATE 1 regulates redox homeostasis in rice endosperm to affect grain quality

• Published in: The Plant cell 2022-04, Vol.34 (5), p.1912-1932
• Main Authors: Wu, Bian, Yun, Peng, Zhou, Hao, Xia, Duo, Gu, Yuan, Li, Pingbo, Yao, Jialing, Zhou, Zhuqing, Chen, Jianxian, Liu, Rongjia, Cheng, Shiyuan, Zhang, Hao, Zheng, Yuanyuan, Lou, Guangming, Chen, Pingli, Wan, Shanshan, Zhou, Mingsong, Li, Yanhua, Gao, Guanjun, Zhang, Qinglu, Li, Xianghua, Lian, Xingming, He, Yuqing
• Format: Article
• Language: English
• Subjects: Edible Grain - genetics; Endosperm - genetics; Gene Expression Regulation, Plant - genetics; Homeostasis - genetics; Oryza - genetics; Oryza - metabolism; Oxidation-Reduction; Regular Issue
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1093/plcell/koac057

Grain chalkiness reduces the quality of rice (Oryza sativa) and is a highly undesirable trait for breeding and marketing. However, the underlying molecular cause of chalkiness remains largely unknown. Here, we cloned the F-box gene WHITE-CORE RATE 1 (WCR1), which negatively regulates grain chalkiness and improves grain quality in rice. A functional A/G variation in the promoter region of WCR1 generates the alleles WCR1A and WCR1G, which originated from tropical japonica and wild rice Oryza rufipogon, respectively. OsDOF17 is a transcriptional activator that binds to the AAAAG cis-element in the WCR1A promoter. WCR1 positively affects the transcription of the metallothionein gene MT2b and interacts with MT2b to inhibit its 26S proteasome-mediated degradation, leading to decreased reactive oxygen species production and delayed programmed cell death in rice endosperm. This, in turn, leads to reduced chalkiness. Our findings uncover a molecular mechanism underlying rice chalkiness and identify the promising natural variant WCR1A, with application potential for rice breeding.