Tillering is one of the most important determinants of biomass and yield in rice (Oryza sativa L.). The capacity of plants to develop tillers from primordial meristems or buds is determined not only by the genotype but also by environmental cues. Here, we characterized the function of rice grassy tiller1 (OsGT1) and its interaction with other genetic and biological factors involved in tiller bud outgrowth in rice by generating OsGT1 RNA interference (RNAi) and overexpression (OX) lines. The tiller number was increased in OsGT1-RNAi mutants but strongly suppressed in OsGT1-OX lines. Expression analysis of OsGT1 in rice phyB mutants and in genotypes carrying various genetic combinations of GT1 RNAi and phyB demonstrated that OsGT1 is not involved in phyB-mediated suppression of tiller development in rice. Expression analysis of fine culm1 (fc1), a rice tb1 homolog, and molecular assays demonstrated that FC1 enhances the expression of OsGT1 by directly binding to its promoter. Comparison of the transcriptomic profiles of fc1 and OsGT1-RNAi mutants revealed differentially expressed genes (DEGs) common to both genotypes. Finally, analysis of tillering phenotypes of OX and RNAi seedlings treated with various phytohormones implied a possible role of OsGT1 in strigolactone-mediated tiller outgrowth. Overall, this study enhances our understanding of the diverse mechanisms of tiller development in grasses.

分蘖是水稻生物量和产量的最重要的决定因素之一（稻属）。植物从原始分生组织或芽形成分ers的能力不仅取决于基因型，还取决于环境提示。在这里，我们通过产生OsGT1 RNA干扰（RNAi）和过表达（OX）系来表征水稻草分till1（OsGT1）的功能及其与水稻分till芽生长相关的其他遗传和生物学因素的相互作用。在OsGT1-RNAi突变体中，分number数增加，但在OsGT1- OXi系中，分strongly数被强烈抑制。OsGT1在水稻phyB中的表达分析突变体和携带GT1 RNAi和phyB各种遗传组合的基因型表明，OsGT1不参与phyB介导的水稻分er发育抑制。优良culm1（fc1），水稻tb1同源物的表达分析和分子分析表明，FC1通过直接与其启动子结合来增强OsGT1的表达。fc1和OsGT1的转录组谱比较-RNAi突变体揭示两种基因型共有的差异表达基因（DEG）。最后，对用各种植物激素处理过的OX和RNAi幼苗的分ing表型进行分析表明，OsGT1可能在雌激素内酯介导的分er生长中发挥作用。总体而言，这项研究增强了我们对草分development发育的多种机制的理解。