棉花超长链脂肪酸代谢关键因子的遗传定位与功能解析

Cotton fiber is an important raw material for textile industries, whose quality directly determines textile traits. Thus, characterization of fiber development mechanism and identification of the key genes associated with fiber quality are vital for fiber quality improvement. Based on in vitro treatment and transcriptome analysis, very-long-chain fatty acids （VLCFAs） was addressed to play important roles in fiber development. Additionally, we found that the KCS genes, the key genes involved in VLCFAs synthesis pathway, were significantly down-regulated in the shortened fiber mutant pag1, resulting in reducing VLCFAs content compared to wild-type (WT) plant. Furthermore, over-expression of KCS2 and KCS6 significantly increased the VCFLAs content in transgenic plants, leading to improvement of fiber quality related to WT. However, the key gene isolation and their cell function characterization associated with VLCFAs metabolism pathway in cotton remain to be revealed. Thereby, in this project, we are ready to assay the content of various VLCFAs components with different carbon chain length and perform genome-wide association study on VLCFAs with genotype data derived from the completed re-sequencing of natural population of upland cotton, by which the key genetic loci or causal genes involved in cotton VLCFAs metabolism should be identified. Subsequently, the correlation between the different types of VCLFAs with the various indexes of fiber quality would be investigated. This study will provide germplasm and gene resources for cotton fiber quality improvement.

棉纤维是纺织工业的重要原料，其品质直接决定纺织品的质量。阐明纤维发育机制和克隆相关基因是纤维品质改良的基础。体外实验和表达谱分析暗示着超长链脂肪酸（VLCFAs）参与调控棉纤维发育。前期研究发现棉花短纤维pag1突变体VLCFAs合成路径中的KCS基因表达显著下调，VLCFAs含量显著也低于受体材料；反之，过量表达KCS2和KCS6基因提高了转基因植株中VLCFAs含量与纤维品质。然而，棉花VLCFAs代谢途径中的关键基因及其作用机制还有待进一步研究。因此，本课题拟在已建立的棉花自然群体及已完成的群体基因型分析的基础之上，结合棉纤维中不同碳链长度的VLCFAs代谢物，进行全基因组关联分析，鉴定参与VLCFAs代谢的关键遗传位点，解析关键基因；在验证这些基因功能的基础上，进一步分析群体中不同类型VLCFAs的含量与纤维品质各项指标的相关性。本研究将为改良棉花纤维品质提供种质和基因资源。

棉纤维是纺织工业的重要原料，其品质直接决定纺织品的质量。阐明纤维发育机制和克隆相关基因是纤维品质改良的基础。体外实验和表达谱分析暗示着超长链脂肪酸（VLCFAs）参与调控棉纤维发育。然而棉花VLCFAs代谢途径中的关键基因及其作用机制还有待进一步研究。针对上述问题，本项目以高质量的陆地棉参考基因组为基础，获得了陆地棉核心种质资源材料的基因型数据；收集了400余份陆地棉核心种质资源材料的纤维样品，分别开展转录组测序分析和VLCFAs含量的测定分析，获得了群体的表达量数据和VLCFAs含量数据；结合VLCFAs含量与基因型数据开展了全基因组关联分析（mGWAS），鉴定出参与VLCFAs代谢的关键遗传位点；结合表达量数据，开展了表达量-全基因组关联分析，获得了全基因组水平的eQTLs信息；结合转录组和eQTLs结果，分析了mGWAS信号区间内的候选基因，并挑选3个候选基因在棉花中进行功能验证，初步明确了候选基因的功能。本研究从正向遗传学入手，解析调控VLCFAs合成的关键遗传位点，为研究其他代谢物在棉花纤维发育中的作用提供了参考。