Zhong Weiping, Wu Lanxin, Li Yan, Li Xiaxuan, Wang Junyi, Pan Jingwen, Zhu Shouhong, Fang Shentao, Yao Jinbo, Zhang Yongshan, Chen Wei
State Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China.
Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, Xinjiang, China.
Plant Biotechnol J. 2024 Nov;22(11):3175-3193. doi: 10.1111/pbi.14439. Epub 2024 Jul 26.
Branch length is an important plant architecture trait in cotton (Gossypium) breeding. Development of cultivars with short branch has been proposed as a main object to enhance cotton yield potential, because they are suitable for high planting density. Here, we report the molecular cloning and characterization of a semi-dominant quantitative trait locus, Short Branch Internode 1(GhSBI1), which encodes a NAC transcription factor homologous to CUP-SHAPED COTYLEDON 2 (CUC2) and is regulated by microRNA ghr-miR164. We demonstrate that a point mutation found in sbi1 mutants perturbs ghr-miR164-directed regulation of GhSBI1, resulting in an increased expression level of GhSBI1. The sbi1 mutant was sensitive to exogenous gibberellic acid (GA) treatments. Overexpression of GhSBI1 inhibited branch internode elongation and led to the decreased levels of bioactive GAs. In addition, gene knockout analysis showed that GhSBI1 is required for the maintenance of the boundaries of multiple tissues in cotton. Transcriptome analysis revealed that overexpression of GhSBI1 affects the expression of plant hormone signalling-, axillary meristems initiation-, and abiotic stress response-related genes. GhSBI1 interacted with GAIs, the DELLA repressors of GA signalling. GhSBI1 represses expression of GA signalling- and cell elongation-related genes by directly targeting their promoters. Our work thus provides new insights into the molecular mechanisms for branch length and paves the way for the development of elite cultivars with suitable plant architecture in cotton.
在棉花（棉属）育种中，枝条长度是一个重要的植株形态性状。培育短枝品种已被提议作为提高棉花产量潜力的主要目标，因为它们适合高密度种植。在此，我们报告了一个半显性数量性状位点——短枝节间1（GhSBI1）的分子克隆与特征分析，该位点编码一个与杯状子叶2（CUC2）同源的NAC转录因子，并受微小RNA ghr-miR164调控。我们证明，在sbi1突变体中发现的一个点突变扰乱了ghr-miR164对GhSBI1的定向调控，导致GhSBI1表达水平升高。sbi1突变体对外源赤霉素（GA）处理敏感。GhSBI1的过表达抑制了枝节间伸长，并导致生物活性GA水平降低。此外，基因敲除分析表明，GhSBI1是棉花中多个组织边界维持所必需的。转录组分析显示，GhSBI1的过表达影响植物激素信号传导、腋芽分生组织起始和非生物胁迫响应相关基因的表达。GhSBI1与GA信号的DELLA阻遏物GAIs相互作用。GhSBI1通过直接靶向其启动子来抑制GA信号传导和细胞伸长相关基因的表达。因此，我们的工作为枝条长度的分子机制提供了新的见解，并为培育具有合适植株形态的棉花优良品种铺平了道路。
