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

Author: Bian Wu, Peng Yun, Hao Zhou, Duo Xia, Yuan Gu, Pingbo Li, Jialing Yao, Zhuqing Zhou, Jianxian Chen, Rongjia Liu, Shiyuan Cheng, Hao Zhang, Yuanyuan Zheng, Guangming Lou, Pingli Chen, Shanshan Wan, Mingsong Zhou, Yanhua Li, Guanjun Gao, Qinglu Zhang, Xianghua Li, Xingming Lian and Yuqing He

Plant Cell. 2022 Apr 26. 34(5):1912-1932.

Abstract: 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 WCR1 (WHITE-CORE RATE 1), 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 (TrJ) and wild rice O. 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.

DOI: 10.1093/plcell/koac057