A bHLH protein, OsBIM1, positively regulates rice leaf angle by promoting brassinosteroid signaling.
A bHLH protein, OsBIM1, positively regulates rice leaf angle by promoting brassinosteroid signaling.
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DOI：
10.1016/j.bbrc.2021.09.035
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发表时间：
2021-09
影响因子：
3.1
通讯作者：
Quanxiang Tian;Junxia Luan;C. Guo;Xingyu Shi;P. Deng;Zhenzhen Zhou;Wenhua Zhang;Like Shen
中科院分区：
文献类型：
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作者：
Quanxiang Tian;Junxia Luan;C. Guo;Xingyu Shi;P. Deng;Zhenzhen Zhou;Wenhua Zhang;Like Shen
水稻叶角是决定植株结构和产量的重要农艺性状。油菜素内酯（BRs）在水稻叶片角度调控中起着至关重要的作用，因此对BRs信号通路的研究越来越多。然而，拟南芥BR信号传导中一些重要成分的同源物尚未在水稻中得到表征。在这项研究中，我们发现了一个名为OsBIM1的水稻bHLH转录因子，它是与AtBIM1 （BES1-Interacting MYC-like Protein1）最接近的水稻同源物。过表达OsBIM1显著增加水稻叶片倾角，而T-DNA敲除突变体OsBIM1和宽型突变体（WT）表现出相似的叶片倾角。osbim1过表达增强了水稻对BR处理的敏感性和应答性。基因表达分析显示，OsILI1的过表达显著增加了促进BR信号传导和应答的关键转录因子fincreased LEAF inclation1 （OsILI1）的转录本。同时，OsBIM1抑制了BR生物合成途径关键酶OsD2的表达。OsBIM1可以结合silil1启动子，增强silil1在BR治疗中的表达。OsBIM1过表达对叶角的促进作用在收获期仍能观察到，但OsBIM1过表达导致籽粒变小，产量降低。这些结果表明，OsBIM1在BR信号传导中起正调控作用，其过表达通过促进BR的敏感性和响应来增加水稻层倾角。
Rice leaf angle is an important agronomic trait determining plant architecture and crop yield. Brassinosteroids (BRs) play crucial roles in controlling rice leaf angle, thus an increasing number of researches were focused on the BR signaling pathway in rice. However, the orthologs of some important components in Arabidopsis BR signaling have not yet been characterized in rice. In this study, we identified a rice bHLH transcription factor named OsBIM1, as the closest rice homolog of AtBIM1 (BES1-Interacting MYC-like Protein1). Overexpression of OsBIM1 significantly increases rice leaf angles, whereas the T-DNA knock-out mutantosbim1and wide type (WT) showed similar leaf inclination.OsBIM1overexpression enhances the sensitivity and response to BR treatment in rice. Gene expression analysis showed that the overexpression of OsBIM1 significantly increased the transcripts ofINCREASED LEAF INCLINATION1(OsILI1) that functions as a key transcription factor promoting BR signaling and response. Meanwhile, OsBIM1 inhibited the expression ofDWARF2(OsD2, a key enzyme in BR biosynthesis pathway). OsBIM1 can bind withOsILI1promoter and enhanceOsILI1expression in response to BR treatment. The promoting effect of OsBIM1 overexpression on leaf angle can still be observed at harvest stage, but overexpression of OsBIM1 resulted in smaller grain size and reduced yield. These results indicate that OsBIM1 functions as a positive regulator in BR signaling, and its overexpression increases rice lamina inclination by promoting BR sensitivity and response.