National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing Jiangsu 210095, China.
National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300, Fenglin Road, 200032 Shanghai, China.
Plant Physiol Biochem. 2017 Dec;121:1-13. doi: 10.1016/j.plaphy.2017.10.001. Epub 2017 Oct 12.
Brassinosteroids (BRs) regulate several aspects of plant growth and development. Although extensive studies have shown that BR signaling is conservative in higher plants, the molecular mechanism of regulating plant architecture in rice still remains to be explored. Here, we characterized a rice mutant named top bending panicle1 (tbp1). Compared to wild type, tbp1 mutant plants displayed semi-dwarf stature, erect leaves, small and round grains, as well as more tillers. Remarkably, the panicles of tbp1 plants were shorter and denser, and the tops of the panicles were curved by rolling of the base of flag leaves, which was later verified as due to reduced bulliform cell numbers. Map-based cloning, together with transgenic complementation and RNA-interference tests, revealed that TBP1 is a member of the somatic embryogenesis receptor kinases (SERKs) family involved in BR signaling. Furthermore, bimolecular fluorescence complementation and co-immunoprecipitation analysis demonstrated that a substitution at 61st amino acid (61) in the tbp1 mutant may result in a reduction of the interaction between TBP1 and OsBRI1 (BR receptor in rice). Taken together, our results demonstrate that TBP1 plays a significant role in regulating plant architecture via the brassinosteroid signaling pathway.
油菜素内酯（BRs）调节植物生长和发育的多个方面。尽管广泛的研究表明，BR 信号在高等植物中是保守的，但调节水稻植物结构的分子机制仍有待探索。在这里，我们对一个名为顶端弯曲穗 1 突变体（tbp1）的水稻突变体进行了描述。与野生型相比，tbp1 突变体植物表现出半矮秆、直立叶片、小而圆的籽粒以及更多的分蘖。值得注意的是，tbp1 植物的穗部更短、更密集，而且穗部的顶端由于旗叶基部的卷曲而弯曲，后来证实这是由于泡状细胞数量减少所致。基于图谱的克隆，以及转基因互补和 RNA 干扰试验表明，TBP1 是参与 BR 信号的体细胞胚胎发生受体激酶（SERKs）家族的一员。此外，双分子荧光互补和共免疫沉淀分析表明，tbp1 突变体中第 61 位氨基酸（61）的取代可能导致 TBP1 与 OsBRI1（水稻中的 BR 受体）之间的相互作用减少。总之，我们的研究结果表明，TBP1 通过油菜素内酯信号通路在调节植物结构中发挥重要作用。
