裙带菜永久F2群体的构建及多环境下主要数量性状的QTL定位研究

Undaria pinnatifida is an important economic seaweed in China. The morphology of U. pinnatifida is complex, with many of the economic traits being quantitative ones. It is easier to bring about errors if only depending on phenotype in the process of selection, resulting in the retardation of the breeding. In order to enhance the breeding efficiency it is urgent to investigate from the molecular level on the QTLs that control the quantitative traits. In this project two inbred lines will be used as parents to obtain an F1 gametophyte clones population, from which an immortalized F2 (IF2) sporophyte population will be established by random crossing between F1 gametophyte clones. Cultivation trial of IF2 population will be conducted in four different environments. Eight major quantitative traits, including plant weight, plant length and width, stipe length and width, sporophyll length, width and weight, will be measured and statistically analyzed. An SNP-based high density genetic map will be constructed by using the SLAF-seq method. The genetic pattern of the quantitative traits and their relationship with environment will be elucidated. The number, location, genetic effect and contribution to the phenotype variations of QTLs on the linkage groups will be analyzed. The stability of QTL mapping under different environments will be evaluated. Common QTLs with major genetic effect under different environment will also be explored. This project will not only shed light on revealing the genetic mechanism of complex quantitative traits of U. pinnatifida, but also lay a foundation for molecular assisted selection and breeding, as well as fine mapping and cloning of QTLs in further studies.

裙带菜是我国重要的大型经济海藻，其形态分化较为复杂，经济性状多为数量性状。在育种过程中仅依赖表型进行选择往往带来偏差，延缓育种的进度。为了提高育种效率，迫切需要从分子水平对数量性状位点（QTL）进行研究。本项目拟以表型差异显著的两个裙带菜近交系作为亲本，建立通过F1配子体克隆随机配对杂交构建永久F2孢子体群体的新方法，在4个不同环境下开展海上栽培实验，对株重、株长和宽、柄长和宽、孢子叶长和宽、孢子叶重等8个主要数量性状进行测定和统计分析，利用SLAF-seq技术构建基于SNP的高密度遗传连锁图谱，旨在揭示上述性状的遗传规律及其与环境的关系，分析QTL在连锁群上的数目、位置、作用方式及其对表型变异的贡献率，分析多环境下QTL定位的稳定性，发掘遗传效应大且在不同环境下稳定表达的QTL，揭示数量性状的分子遗传机制，为实施分子标记辅助选择以及进一步开展 QTL精细定位和克隆奠定基础。

裙带菜是我国重要的大型经济海藻，其形态分化较为复杂，经济性状多为数量性状。在育种过程中仅依赖表型进行选择往往带来偏差，延缓育种的进度。为了提高育种效率，迫切需要从分子水平对数量性状位点（QTL）进行研究。本项目以基因型差异显著的雌、雄配子体克隆作为亲本，提出并建立了通过全同胞F2配子体克隆随机配对杂交构建永久F2（IF2）孢子体群体的新方法。开发了高多态性的SSR标记30个，利用它们完成了IF2群体的亲权鉴定，证实了所构建的IF2群体的准确性。开展了亲本、F1及IF2孢子体的海上栽培实验，完成了株重、株长、株宽、叶片长、柄宽、孢子叶长、宽和重等8个主要经济性状的测定和统计分析，发现所有性状的测量值均符合正态分布，完成了不同性状之间的关联性分析。完成了一株雄性配子体克隆的全基因组测序与染色体水平的组装，以此为基础，对F2配子体克隆群体进行重测序和SNP分型。根据构建IF2群体过程中的配子体配对方式推断IF2群体每个孢子体株系的基因型，由此构建了IF2群体的高密度遗传连锁图谱，总图距为2326.89cM，分为30个连锁群。总共包含1679个bin，平均每个连锁群56个bin，平均bin间距1.5cM。以遗传连锁图谱为基础，通过复合区间作图法对上述8个主要数量性状进行QTL定位分析，成功对其中6个性状（株长、株宽、株重、柄宽、孢子叶长和重）进行了定位。总共定位到16个QTL，其中柄宽和孢子叶重各4个，株宽和孢子叶长各3个，株长和株重各1个。每个QTL表型贡献率的范围为2.82%-37.7%。评估了每个QTL的加性和显性效应值。本项目的研究结果为揭示裙带菜数量性状遗传的分子机制，为实施分子标记辅助选择以及进一步开展QTL精细定位和克隆奠定了重要的基础。