GhSBI基因调控棉花果枝节间长度的分子机理解析

Plant architecture is the important agronomic traits that contribute to crop yield and mechanization. The length of branch internode, characterizing the cotton canopy, is the key agronomic trait which plays a crucial role in yield output and picker-harvesting performance. In our previous study, Chuannong72318, a mutant with extreme short fruiting branch internode, showed a single genetic locus in genetic analysis and molecular marker mapping. The gene GhSBI ( short branch internode) was located on a ~420kb interval in chromosome D01 of upland cotton by fine mapping, which contain six canditate genes. In this study, cytological observation, gene expression pattern, overexpression in transgenic cotton, RNAi by VIGS and CRISPR/Cas9 gene edit were applied to verify the function of GhSBI. The protein interaction and transcriptome sequencing were performed to reveal the regulatory networks of GhSBI in determining the short branch internode. This study will give insight into the development of branch internode in cotton by map-based cloning and gene edit, which supports the molecular design breeding in cotton theoretically and technically.

株型结构是作物提高产量，适应机械化需求的重要综合性状。果枝节间长度直接决定了棉花的株型，是影响棉花产量和机采性能的关键农艺性状。本项目组前期对陆地棉果枝节间极度缩短的突变体川农72318进行了遗传分析和分子标记定位，发现其短果节性状由单位点控制。通过精细定位，将棉花短果节基因GhSBI(Short Branch Internode)定位到D01染色体上约420kb的区间，包含6个候选基因。本研究拟通过细胞学观察，GhSBI表达模式分析，基于基因编辑、转基因等技术的基因功能分析，确定SBI的候选基因，并验证GhSBI是棉花短果节性状的决定因子；通过蛋白互作及转录组测序，进一步解析GhSBI在棉花果枝节间伸长中的表达调控网络。本项目的开展有助于解析棉花果枝节间发育的分子机理，为棉花株型育种提供理论指导和技术支撑。

棉花短果枝材料适于高密植和机械化采收。本研究在前期研究的基础上，将短果节突变sbi的候选基因GhSBI作为研究对象，采用转基因超表达、基因编辑等技术验证GhNB在棉花果枝发育中的生物学功能，并分析其表达模式和调控模式。结果表明，棉花短果节突变体sbi的节间细胞比正常材料短，节间伸长受到抑制。GUS染色表明，GhSBI主要在棉花的茎尖分生组织，发育早期花药，心皮中优势表达。Ghsbi突变导致基因表达量上升。超表达GhSBI基因会抑制节间伸长，而编辑GhSBI基因会导致子叶融合，花发育异常等表型。转录组分析表明，sbi突变与植物激素信号转导途径等相关。酵母双杂试验表明，GhSBI基因与GA 信号途径的关键负调控因子GhGAI 直接互作。本研究表明，GhSBI是棉花果枝发育的重要调控因子，利用调控GhSBI基因的表达量或蛋白活性，能相应调控棉花的株高、果枝长度等性状，是棉花株型改良的重要目标基因。