细胞壁相关的类受体激酶（GhWAKL3）调控棉花衣分性状的分子机制

The lint percentage, as a major factor which can affect cotton lint yield, plays a vital role in high-yield breeding of cotton. The cell wall-associated receptor-like kinase (WAK/WAKL) is important sensors for directly linking the extracellular matrix with intracellular compartments in plants. In our previous study, GhWAKL3 was identified to control the lint percentage through the artificial selection analysis and correlation analysis. And, overexpression of the gene in Arabidopsis significantly increased the density of root hairs and trichomes. Therefore, it was deduced that GhWAKL3 might be a key factor that perceived the signals of significant changes in cell wall during the process of fiber initiation, and transferred the signals to the cytoplasm, resulting in producing more fiber initials to improve the lint percentage. In the study, the overexpression and CRISPR/Cas9-mediated gene editing in cotton, and the analysis of kinase activity and expression profile will be carried out to validate the function of GhWAKL3 in controlling lint percentage. Then, the yeast two-hybrid, GST pull down and bimolecular fluorescence complementation assays will be employed to screen genes and pathways regulated by GhWAKL3. These results will provide new evidence for elucidating the molecular mechanism of controlling lint percentage, and offer genetics resource and theoretical foundation for molecular breeding for high yield in cotton.

衣分是决定纤维产量的主要因素之一，在棉花高产育种中起着重要作用。细胞壁相关的类受体激酶（WAK/WAKL）负责植物细胞壁与细胞质之间的信号转导。前期工作中，我们通过人工选择分析和关联分析鉴定到控制衣分性状的GhWAKL3基因，在拟南芥中超量表达显著增加根毛和表皮毛的密度。我们推测该GhWAKL3基因可能作为关键因子感知纤维起始过程中细胞壁的明显变化，进而将信号传递到细胞内，促进更多的纤维细胞突起，从而提高衣分。在此基础上，本项目拟通过在棉花中超量表达和CRISPR/Cas9系统介导的基因编辑，同时分析其激酶活性和表达模式，验证GhWAKL3基因在衣分性状形成中的功能；利用酵母双杂、GST融合蛋白沉降和双分子荧光互补等技术，确定该基因的互作蛋白，明确GhWAKL3基因调控的基因和途径。本研究将为阐明衣分性状形成的分子机制提供新的实验证据，并为棉花高产分子育种提供基因资源和理论支撑。

本项目通过基因表达分析，明确细胞壁相关的类受体激酶基因GhWAKL3在纤维起始期和伸长期丰度表达；利用亚细胞定位实验，确定GhWAKL3基因编码的蛋白质定位在细胞膜上；基因敲除GhWAKL3棉花的纤维突起和伸长受阻，衣分降低；在棉花中超量表达GhWAKL3促进纤维突起和伸长，提高衣分；互作蛋白筛选，鉴定出GhWAKL3基因编码蛋白质与蔗糖转运蛋白基因GhSUT6编码蛋白质存在相互作用；互作机制解析，发现GhWAKL3可以增强GhSUT6的蔗糖转运活性；超量表达GhSUT6棉花的纤维突起增多，纤维长度变长，衣分提高。研究结果揭示了GhWAKL3与GhSUT6互作调控棉花衣分性状的分子机制，为棉花高产优质分子育种提供基因资源和理论支撑。

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