大蒜资源基因型评价及抽薹开花相关性状的关联分析

Garlic (Allium sativum L.), an asexually propagated crop, is grown as an important vegetable and medicinal plant. However, the research and breeding is serious weak and very limited studies could be refered about the genetic background of garlic germplasm resources.The characteristics of vegetative propagation of garlic makes it very difficult to construct mapping populations for research on genetic mechanism, the development of elite genes and breeding. Why the cultivated varieties of garlic lost his sexual propagation ability and how to restore the difficult issue bewildering the scientists in the world. These two issues are urgent problems that breeder expected to solve. In this study, the diversity, population structure and genetic relationship of 600 accessions of garlic germplasm from the National Nursery of Vegetatively Propagated Vegetable Germplasm will be studied using Genotyping-by-Sequencing.The transcriptomes of characteristic including the wild garlic which possess the fertile ability, the different types of cultivated variety germplasm with different fertile ability will be sequenced analyzed by bulked segregant analysis to identificate the candidate genes. The profile of the gene relative bolting and flowering will be analyzed and the differentially expressed genes will be found out. Besides, the markers associated with flowering and bolting identified using association analysis will be compared with the different genes identified by transcriptome sequencing. The research would improve the utilazation effect of garlic germplasm and lay the foundation for the study of sexual mechanism of garlic.

大蒜为典型的无性繁殖作物，很难人工杂交构建研究所需的各种作图群体，其庞大而复杂的基因组缺乏必要的生物学信息，严重阻碍了该作物的遗传学研究和有性育种实践。大蒜自然变异丰富，但其遗传背景尚不清楚，制约着其重要农艺性状相关基因挖掘和有效利用。因此，栽培大蒜和野生大蒜资源的亲缘关系分析和有性育种一直是大蒜研究中的渴望解决的难题。针对上述问题，项目将通过简化基因组技术(GBS)对栽培和野生大蒜共600份资源进行基因型鉴定，深入评价不同类型大蒜资源之间的亲缘关系，特别是抽薹开花相关性状的进化关系；通过对稀有可育野生大蒜及不育资源花期花序组织进行混池转录组测序，开发抽薹开花候选基因标记；利用关联分析方法寻找与抽薹开花相关联的位点，获得高效分子辅助筛选标记；获得控制抽薹开花相关的候选基因，并进行初步功能验证。项目实施，将为特异大蒜资源的筛选提供分子标记，为有性机理研究奠定基础。

大蒜为典型的无性繁殖作物，很难人工杂交构建研究所需的各种作图群体，其庞大而复杂的基因组缺乏必要的生物学信息，严重阻碍了对其遗传学研究和有性育种实践。大蒜自然变异丰富，但其遗传背景尚不清楚，制约着其重要农艺性状相关基因挖掘和有效用。因此，栽培大蒜和野生大蒜资源的亲缘关系分析和有性育种一直是大蒜研究中的渴望解决的难题。针对上述问题，项目通过简化基因组技术606份资源进行基因型鉴定，深入评价不同类型大蒜资源之间的亲缘关系，特别是抽薹开花相关性状的进化关系；通过对稀有可育野生大蒜及不育资源花期花序组织进行混池转录组测序，开发抽薹开花候选基因标记；利用关联分析方法寻找与抽薹开花相关联的位点，获得高效分子辅助筛选标记；获得控制抽薹开花相关的候选基因，并进行初步功能验证。结果如下：对606份大蒜种质资源进行简化基因组GBS测序，共检测到1,100,259个SNPs。系统发育树、群体结构和PCA分析结果显示大蒜种质可分为5个类群。亚洲种质分散在5个类群中，表明亚洲大蒜种质基因型较为丰富；欧洲和北美洲种质主要分布在Pop2和Pop4中，南美洲种质主要分布在pop4中，非洲种质主要分布在Pop1和Pop5中。Pop2包含有其它类群的混合遗传成分，遗传多样性最高；对606份大蒜种质的抽薹性进行调查，发现328份种质为完全抽薹型，103份种质为不完全抽薹型，175份种质为不抽薹型。这三种类型分布在五大洲，超过一半的亚洲种质都是完全抽薹型。在受选择区域共筛选到1,238个候选基因，这些基因显著富集在分生组织从营养到生殖阶段转变、生殖芽系统发育、生殖过程等生物学过程；基于转录组数据、关联分析与差异基因差减比对挖掘到1个非同义突变SNP为控制抽薹开花和蒜薹数量性状的候选基因。利用WGCNA构建基因共表达网络，获得3个基因可作为研究大蒜育性的重要候选基因。项目发表文章7篇，获得专利3项。项目实施，将为特异大蒜资源的筛选提供分子标记，为有性机理研究奠定基础。