Tiller angle is one of the most important agronomic traits and one key factor for wheat ideal plant architecture, which can both increase photosynthetic efficiency and greatly enhance grain yield. Here, a deacetylase HST1-like (TaHST1L) gene controlling wheat tiller angle was identified by the combination of a genome-wide association study (GWAS) and bulked segregant analysis (BSA). Ethyl methane sulfonate (EMS)-mutagenized tetraploid wheat lines with the premature stop codon of TaHST1L exhibited significantly smaller tiller angles than the wild type. TaHST1L-overexpressing (OE) plants exhibited significantly larger tiller angles and increased tiller numbers in both winter and spring wheat, while TaHST1L-silenced RNAi plants displayed significantly smaller tiller angles and decreased tiller numbers. Moreover, TaHST1L strongly interacted with TaIAA17 and inhibited its expression at the protein level, and thus possibly improved the content of endogenous auxin in the basal tissue of tillers. The transcriptomics and metabolomics results indicated that TaHST1L might change plant architecture by mediating auxin signal transduction and regulating endogenous auxin levels. In addition, a 242-bp insertion/deletion (InDel) in the TaHST1L-A1 promoter altered transcriptional activity and TaHST1L-A1b allele with the 242-bp insertion widened the tiller angle of TaHST1L-OE transgenic rice plants. Wheat varieties with TaHST1L-A1b allele possessed the increased tiller angle and grain yield. Further analysis in wheat and its progenitors indicated that the 242-bp InDel possibly originated from wild emmer and was strongly domesticated in the current varieties. Therefore, TaHST1L involved in the auxin signalling pathway showed the big potential to improve wheat yield by controlling plant architecture.

中文翻译：

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HST1 样基因通过调控普通小麦内源生长素控制分蘖角度

分蘖角是最重要的农艺性状之一，是小麦理想株型的关键因素之一，它既能提高光合效率，又能大大提高籽粒产量。在这里，通过全基因组关联研究 (GWAS) 和批量分离分析 (BSA) 的组合鉴定了控制小麦分蘖角度的脱乙酰酶HST1 样( TaHST1L ) 基因。甲磺酸乙酯 (EMS) 诱变的四倍体小麦品系与 TaHST1L 的过早终止密码子相比野生型表现出明显更小的分蘖角。TaHST1L-过表达 (OE) 植物在冬小麦和春小麦中表现出显着更大的分蘖角度和增加的分蘖数，而TaHST1L-沉默的 RNAi 植物显示出明显更小的分蘖角度和减少的分蘖数。此外，TaHST1L与TaIAA17强相互作用，在蛋白水平抑制其表达，从而可能提高分蘖基部组织中内源性生长素的含量。转录组学和代谢组学结果表明，TaHST1L可能通过介导生长素信号转导和调节内源生长素水平来改变植物结构。此外，TaHST1L-A1启动子中的 242-bp 插入/缺失 (InDel) 改变了转录活性，而带有 242-bp 插入的TaHST1L-A1b等位基因扩大了TaHST1L- OE 转基因水稻植株的分蘖角。具有TaHST1L-A1b 的小麦品种等位基因具有增加的分蘖角和籽粒产量。对小麦及其祖先的进一步分析表明，242-bp InDel 可能起源于野生二粒小麦，并在当前品种中得到了强烈驯化。因此，参与生长素信号通路的TaHST1L显示出通过控制植物结构来提高小麦产量的巨大潜力。