Liu Rongjia, Zhao Da, Li Pingbo, Xia Duo, Feng Qingfei, Wang Lu, Wang Yipei, Shi Huan, Zhou Yin, Chen Fangying, Lou Guangming, Yang Hanyuan, Gao Haozhou, Wu Bian, Chen Junxiao, Gao Guanjun, Zhang Qinglu, Xiao Jinghua, Li Xianghua, Xiong Lizhong, Li Yibo, Li Zichao, You Aiqing, He Yuqing
National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.
Institute of Food Crops, Hubei Academy of Agricultural Sciences, Wuhan 430070, China.
Plant Commun. 2025 Jan 13;6(1):101178. doi: 10.1016/j.xplc.2024.101178. Epub 2024 Oct 28.
Grain size, which encompasses grain length, width, and thickness, is a critical determinant of both grain weight and quality in rice. Despite the extensive regulatory networks known to determine grain length and width, the pathway(s) that regulate grain thickness remain to be clarified. Here, we present the map-based cloning and characterization of qGT3, a major quantitative trait locus for grain thickness in rice that encodes the MADS-domain transcription factor OsMADS1. Our findings demonstrate that OsMADS1 regulates grain thickness by affecting sugar delivery during grain filling, and we show that OsMADS1 modulates expression of the downstream monosaccharide transporter gene MST4. A natural variant leads to alternative splicing and thus to a truncated OsMADS1 protein with attenuated transcriptional repressor activity. The truncated OsMADS1 protein results in increased expression of MST4, leading to enhanced loading of monosaccharides into the developing endosperm and thereby increasing grain thickness and improving grain quality. In addition, our results reveal that NF-YB1 and NF-YC12 interact directly with OsMADS1, acting as cofactors to enhance its transcriptional activity toward MST4. Collectively, these findings reveal a novel molecular mechanism underlying grain thickness regulation that is controlled by the OsMADS1-NF-YB1-YC12 complex and has great potential for synergistic improvement of grain yield and quality in rice.
粒形，包括粒长、粒宽和粒厚，是水稻粒重和品质的关键决定因素。尽管已知存在广泛的调控网络来决定粒长和粒宽，但调控粒厚的途径仍有待阐明。在此，我们展示了基于图谱克隆和鉴定的qGT3，它是水稻粒厚的一个主要数量性状位点，编码MADS结构域转录因子OsMADS1。我们的研究结果表明，OsMADS1通过影响灌浆期的糖分输送来调控粒厚，并且我们发现OsMADS1调节下游单糖转运蛋白基因MST4的表达。一个自然变异导致选择性剪接，从而产生具有减弱转录抑制活性的截短型OsMADS1蛋白。截短型OsMADS1蛋白导致MST4表达增加，从而增强单糖向发育中的胚乳的装载，进而增加粒厚并改善粒质。此外，我们的结果揭示，NF-YB1和NF-YC12直接与OsMADS1相互作用，作为辅因子增强其对MST4的转录活性。总的来说，这些发现揭示了一种由OsMADS1-NF-YB1-YC12复合体控制的粒厚调控新分子机制，在协同提高水稻产量和品质方面具有巨大潜力。
