Wu Mingming, Cai Maohong, Zhai Rongrong, Ye Jing, Zhu Guofu, Yu Faming, Ye Shenghai, Zhang Xiaoming
Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, China.
Front Plant Sci. 2023 Mar 9;14:1136849. doi: 10.3389/fpls.2023.1136849. eCollection 2023.
Rice kernel quality has vital commercial value. Grain chalkiness deteriorates rice's appearance and palatability. However, the molecular mechanisms that govern grain chalkiness remain unclear and may be regulated by many factors. In this study, we identified a stable hereditary mutant, (), which has a white belly in its mature grains. The grain filling rate of was lower than that of the wild type across the whole filling period, and the starch granules in the chalky part were oval or round and loosely arranged. Map-based cloning showed that was an allelic mutant of , which encodes a mitochondrion-targeted P-type pentatricopeptide repeat protein. Amino acid sequence analysis found that two PPR motifs present in the C-terminal of WBG1 were lost in wbg1. This deletion reduced the splicing efficiency of intron 1 to approximately 50% in , thereby partially reducing the activity of complex I and affecting ATP production in grains. Furthermore, haplotype analysis showed that was associated with grain width between and rice varieties. These results suggested that influences rice grain chalkiness and grain width by regulating the splicing efficiency of intron 1. This deepens understanding of the molecular mechanisms governing rice grain quality and provides theoretical support for molecular breeding to improve rice quality.
水稻籽粒品质具有重要的商业价值。籽粒垩白会降低水稻的外观和适口性。然而，控制籽粒垩白的分子机制仍不清楚，可能受多种因素调控。在本研究中，我们鉴定出一个稳定的遗传突变体（），其成熟籽粒腹部为白色。在整个灌浆期，该突变体的籽粒灌浆速率低于野生型，垩白部分的淀粉粒呈椭圆形或圆形且排列松散。图位克隆表明，该突变体是WBG1的等位突变体，WBG1编码一个定位于线粒体的P型五肽重复蛋白。氨基酸序列分析发现，wbg1中WBG1 C末端存在的两个PPR基序缺失。这种缺失使该突变体中WBG1内含子1的剪接效率降低至约50%，从而部分降低了复合体I的活性并影响了该突变体籽粒中的ATP产生。此外，单倍型分析表明，在粳稻和籼稻品种之间，WBG1与籽粒宽度相关。这些结果表明，WBG1通过调控WBG1内含子1的剪接效率影响水稻籽粒垩白和籽粒宽度。这加深了对控制水稻籽粒品质分子机制的理解，并为改良水稻品质的分子育种提供了理论支持。
