Ye Yongheng, Cheng Zhiyuan, Yang Xinjing, Yang Suxin, Tang Kuanqiang, Yu Hui, Gao Jinshan, Zhang Yaohua, Leng Jiantian, Zhang Wei, Zhang Ye, Bu Moran, Liang Zhengwei, Dong Zhicheng, Zhang Zhonghui, Feng Xianzhong
Key Laboratory of Soybean Molecular Design Breeding, State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China.
University of Chinese Academy of Sciences, Beijing, China.
Plant Biotechnol J. 2025 Jul;23(7):2978-2993. doi: 10.1111/pbi.70124. Epub 2025 May 7.
Stem lodging resistance plays a critical role in maintaining soybean yield stability, yet the molecular mechanisms governing stem development and lodging tolerance remain poorly understood. Here, we report the characterization of lodging-related mutant 3 (lrm3), a weak-stemmed soybean line exhibiting increased lodging susceptibility. Molecular cloning revealed that LRM3 encodes a U-box E3 ubiquitin ligase that physically interacts with the transcription factor MYB6, targeting it for 26S proteasome-mediated degradation. Transcriptomic and chromatin immunoprecipitation analyses demonstrated that MYB6 binds directly to the promoter regions of PHENYLALANINE AMMONIA-LYASE (PAL) genes, repressing their transcriptional activity and consequently reducing lignin biosynthesis and secondary cell wall deposition in stems. Population genetic analysis identified three major LRM3 haplotypes, with Haplotype 1 preferentially retained in landraces and modern cultivars, suggesting artificial selection during domestication. Collectively, our findings elucidate a previously uncharacterized regulatory mechanism integrating ubiquitin-mediated proteolysis and phenylpropanoid metabolism to enhance stem mechanical strength. This study provides novel genetic insights and molecular tools for improving lodging resistance in soybean breeding programs.
茎秆抗倒伏性对维持大豆产量稳定性起着关键作用，然而，调控茎秆发育和抗倒伏性的分子机制仍知之甚少。在此，我们报道了倒伏相关突变体3（lrm3）的特征，这是一个茎秆较弱、倒伏易感性增加的大豆品系。分子克隆显示，LRM3编码一个U-box E3泛素连接酶，它与转录因子MYB6发生物理相互作用，将其靶向26S蛋白酶体介导的降解。转录组学和染色质免疫沉淀分析表明，MYB6直接结合苯丙氨酸解氨酶（PAL）基因的启动子区域，抑制其转录活性，从而减少茎秆中木质素的生物合成和次生细胞壁的沉积。群体遗传分析确定了三种主要的LRM3单倍型，单倍型1在地方品种和现代品种中优先保留，表明驯化过程中存在人工选择。总的来说，我们的研究结果阐明了一种以前未被描述的调控机制，该机制整合了泛素介导的蛋白水解和苯丙烷代谢，以增强茎秆机械强度。本研究为提高大豆育种计划中的抗倒伏性提供了新的遗传见解和分子工具。
