Huang Kunyong, Chen Long, Jiao Guiai, Ruan Zheyan, Li Xinwei, Tang Shaoqing, Hu Peisong, Wei Xiangjin
State Key Laboratory of Rice Biology and Breeding, China National Center for Rice Improvement, China National Rice Research Institute, Hangzhou 310006, China.
Environment-Friendly Crop Germplasm Innovational and Genetic Improvement Key Laboratory of Sichuan Province, Chengdu 610066, China.
Life (Basel). 2025 Jun 16;15(6):962. doi: 10.3390/life15060962.
Starch is the primary component of the endosperm and plays a crucial role in rice quality. Although the enzymes involved in starch synthesis have been extensively studied, the transcription factors that regulate these enzymes remain largely unknown. Here, we identified a MYB family transcription factor, , that regulates starch biosynthesis in rice. is highly expressed during endosperm development. Mutations of result in reduced grain thickness and a decrease in 1000-grain weight. The endosperm of mutants exhibit rounded and loosely packed starch granules, decreased amylose content, altered fine structure of amylopectin, and modified physicochemical properties. The analysis of RT-qPCR showed that the expression of several starch-synthesis enzyme-coding genes (SSEGs), including , , , , , , and , is altered in mutants. Further experiments indicated that OsMYBR1 directly binds to the promoters of , , , , , and , resulting in an increase in the expression of but a decrease in the expression of , , and . In contrast, -overexpressing endosperm appears normal, with starch granule morphology, increased amylopectin content, and improved alkali spreading value, indicating enhanced rice eating and cooking quality (ECQ). These findings suggest that the overexpression of could be a promising strategy for improving rice ECQ.
淀粉是胚乳的主要成分，在水稻品质中起着关键作用。尽管参与淀粉合成的酶已被广泛研究，但调控这些酶的转录因子仍 largely 未知。在此，我们鉴定出一个 MYB 家族转录因子，其调控水稻中的淀粉生物合成。在胚乳发育过程中高度表达。的突变导致谷粒厚度降低和千粒重下降。突变体的胚乳表现出圆形且排列松散的淀粉颗粒、直链淀粉含量降低、支链淀粉精细结构改变以及理化性质改变。RT-qPCR 分析表明，包括、、、、、和在内的几个淀粉合成酶编码基因（SSEGs）的表达在突变体中发生改变。进一步实验表明，OsMYBR1 直接结合到、、、、和的启动子上，导致表达增加，但、和表达降低。相反，过表达的胚乳看起来正常，具有淀粉颗粒形态、支链淀粉含量增加以及碱消值提高，表明水稻食味和蒸煮品质（ECQ）增强。这些发现表明，的过表达可能是改善水稻 ECQ 的一种有前景的策略。
