茶树杂交系F1代的GWAS分析及重要品质性状基因的挖掘

Excellent tea tree resource is the most critical material in tea production, which affects tea quality and economic value. To elucidate the molecular genetic mechanism of tea tree's excellent characters and to excavate the main character genes is an important basis for the improvement of tea tree varieties and the improvement of tea quality and economic value. This study chose the hybrid group whose parents was established by the improved varieties of big-leaf and small-leaf tea tree as the material. Firstly, developing the biological characteristics analysis of the parents and their F1 plants to obtain the biological genetic variation law of their parents; Secondly, the main biochemical indexes of the parents and their F1 plants were determined to obtain the genetic changes of the main chemical indexes of parental leaves; Thirdly, high throughput sequencing technology was used to sequence the genomes of the parents and their F1 generation plants to obtain a large number of SNPS; Fourthly, proceeding principal component analysis, group stratification study, linkage disequilibrium analysis and correction for biological characteristics data, biochemical indexes content, and SNP obtained by high throughput sequencing of the parents and their F1 plants, and finally formed the association character scanning of the parents and their F1 plants scope of genome-wide to obtain important traits specific expression genes and loci. Through the above research, we hope to exactly find out the related gene of parent excellent traits in order to provide strong support and technical guarantee for tea tree molecular breeding.

优良的茶树资源是茶叶生产中最关键的物质资料，影响到茶叶品质和经济价值。阐明茶树优异性状的分子遗传机理，挖掘主要性状基因，是茶树品种改良、提高茶叶品质及经济价值的重要基础。本研究选用优异的大叶茶树良种和小叶茶良种以及作为亲本所构建的杂交群体为材料，一是开展亲本及其F1代植株的生物学特性分析，获得亲本的生物学特性遗传变异规律；二是对亲本及其F1代植株的主要生化指标进行测定，获得亲本叶片主要化学指标的遗传变化情况；三是利用高通量测序技术对亲本及其F1代植株基因组进行测序，获得大量SNP；四是对亲本及其F1代植株的生物学特性数据和生化指标含量以及高通量测序获得的SNP，进行主成分分析、群体分层研究、连锁不平衡分析和校正，最后形成亲本及其F1代植株全基因组范围的关联性状扫描，获得亲本重要性状特定表达基因及位点。通过上述研究，希望准确发掘到亲本优异性状的关联基因，为茶树分子育种提供有力支持和技术保障。

本项目以品质性状差异明显的大叶种茶树品种（云茶1号）和小叶种茶树品种（金萱）为亲本，采用人工杂交育种方法获得的F1代群体为材料，开展生物学特性分析、生化指标测定和高通量测序与分析。表型数据分析表明，F1代单株在12个性状上的遗传特性较复杂，出现变异的几率较大。GC、咖啡碱及儿茶素总量接近正态分布的形式，铁、锰等10种矿物元素含量和芳香类化合物相对含量存在丰富的变异类型。利用GBS简化基因组测序、质量控制和数据分析，鉴定得到139743个高质量的SNP位点。将过滤后得到的高质量SNPs分别与143份杂交F1代单株的表型性状和品质性状的相关指标进行GWAS分析，共筛选到248个与发芽期、叶面积等表型性状相关的候选基因，挖掘出与ECG、CG和可可碱含量等品质直接相关的功能基因19个。项目研究结果为解析茶树优异性状的形成和茶树遗传育种提供了重要的理论基础。