Liu Yunchuan, Wang Mingming, Wang Yaojia, Liu Haixia, Xi Wei, Seung David, Wang Xiaolu, Zhuang Lei, Li Huifang, Li Tian, Liu Hongxia, Hou Jian, Liu Xu, Hao Chenyang, Zhang Xueyong
State Key Laboratory of Crop Gene Resources and Breeding/National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China; John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
Mol Plant. 2025 Jun 18. doi: 10.1016/j.molp.2025.06.007.
Starch is the primary storage compound in wheat grains and is essential for both flour quality and grain weight. In this study, we identified TaMYB44, an R2R3-MYB transcription factor gene that controls starch content in wheat grains, through a genome-wide association study. The TaMYB44 homoeologs were predominantly expressed in developing grains, with peak levels observed 10 days after pollination. Functional analyses revealed that TaMYB44 acts as a negative regulator of starch synthesis in the endosperm, limiting grain size by repressing starch synthesis-related genes and modulating secondary metabolism. Knockout mutants of TaMYB44 exhibited significantly increased starch accumulation, larger grain size, and improved yield stability across diverse growing environments. Furthermore, we discovered that TaWDR1 interacts with TaMYB44, alleviating its repressive effects to restore starch synthesis and enhance grain weight. Notably, the functions of MYB44 appear to be partially conserved between wheat and rice, underscoring its potential as a target for genetic improvement. Our findings offer valuable insights into the transcriptional regulation of starch synthesis and provide genetic resources for enhancing grain yield in wheat and rice.
淀粉是小麦籽粒中的主要贮藏化合物，对面粉品质和粒重都至关重要。在本研究中，我们通过全基因组关联研究鉴定出TaMYB44，这是一个控制小麦籽粒淀粉含量的R2R3-MYB转录因子基因。TaMYB44同源基因在发育中的籽粒中主要表达，授粉后10天观察到峰值水平。功能分析表明，TaMYB44作为胚乳中淀粉合成的负调控因子，通过抑制淀粉合成相关基因和调节次生代谢来限制籽粒大小。TaMYB44的敲除突变体在不同生长环境下表现出淀粉积累显著增加、籽粒尺寸更大以及产量稳定性提高。此外，我们发现TaWDR1与TaMYB44相互作用，减轻其抑制作用以恢复淀粉合成并增加粒重。值得注意的是，MYB44的功能在小麦和水稻之间似乎部分保守，突出了其作为遗传改良靶点的潜力。我们的研究结果为淀粉合成的转录调控提供了有价值的见解，并为提高小麦和水稻的籽粒产量提供了遗传资源。
