Wang Miao, Sun Shi, Wu Cunxiang, Han Tianfu, Wang Qingyu
College of Plant Science, Jilin University, Changchun 130062, Jilin, China.
Ministry of Agriculture Key Laboratory of Soybean Biology (Beijing), Institute of Crop Sciences, the Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Int J Mol Sci. 2014 Mar 4;15(3):3871-88. doi: 10.3390/ijms15033871.
Brassinosteroids (BRs) constitute a group of steroidal phytohormones that contribute to a wide range of plant growth and development functions. The genetic modulation of BR receptor genes, which play major roles in the BR signaling pathway, can create semi-dwarf plants that have great advantages in crop production. In this study, a brassinosteroid insensitive gene homologous with AtBRI1 and other BRIs was isolated from Glycine max and designated as GmBRI1. A bioinformatic analysis revealed that GmBRI1 shares a conserved kinase domain and 25 tandem leucine-rich repeats (LRRs) that are characteristic of a BR receptor for BR reception and reaction and bear a striking similarity in protein tertiary structure to AtBRI1. GmBRI1 transcripts were more abundant in soybean hypocotyls and could be upregulated in response to exogenous BR treatment. The transformation of GmBRI1 into the Arabidopsis dwarf mutant bri1-5 restored the phenotype, especially regarding pod size and plant height. Additionally, this complementation is a consequence of a restored BR signaling pathway demonstrated in the light/dark analysis, root inhibition assay and BR-response gene expression. Therefore, GmBRI1 functions as a BR receptor to alter BR-mediated signaling and is valuable for improving plant architecture and enhancing the yield of soybean.
油菜素甾醇（BRs）是一类甾体植物激素，对植物的多种生长发育功能有重要作用。在BR信号通路中起主要作用的BR受体基因的遗传调控能够培育出半矮化植株，这些植株在作物生产中具有很大优势。在本研究中，从大豆中分离出一个与拟南芥AtBRI1及其他BRIs同源的油菜素甾醇不敏感基因，并将其命名为GmBRI1。生物信息学分析表明，GmBRI1具有一个保守的激酶结构域和25个串联的富含亮氨酸重复序列（LRRs），这些是BR受体接收和响应BR的特征，并且其蛋白质三级结构与AtBRI1具有显著相似性。GmBRI1转录本在大豆下胚轴中更为丰富，并且对外源BR处理有上调响应。将GmBRI1转入拟南芥矮化突变体bri1 - 5可恢复其表型，尤其是在荚果大小和株高方面。此外，这种互补作用是由光/暗分析、根抑制试验和BR响应基因表达所证明的BR信号通路恢复的结果。因此，GmBRI1作为BR受体发挥作用，改变BR介导的信号传导，对于改善植株形态和提高大豆产量具有重要价值。
