花生栽野杂种高油新种质含油量的QTL定位

Increasing oil content is a major objective of peanut breeding in China. However, the progress of peanut breeding for high oil content has been limited owing to lack of elite resource with high and stable oil content and the poor knowledge of genetic basis for oil content. The results from the previous studies indicate that the oil content in the wild Arachis species is significantly higher than that in cultivated varieties. The wild Arachis species is the important source for oil improvement of cultivated peanut. In the present project, two novel peanut genotypes with high and stable oil content derived from interspecific hybridization between cultivated and different wild species will be crossed with low oil genotypes to develop F1, F2 and recombinant inbred line (RIL) populations. The genetic properties of oil content will be analyzed based on the variation in the F1, F2 and RIL populations. Meanwhile, the genetic diversity of the RILs will be detected by SNP markers. Genetic maps will be constructed based on the SNP genotypes. The QTLs for oil content will be identified by linkage analysis. The relationship between the oil content and the number of QTLs and the relationship among the different QTLs will be further analyzed based on oil content and QTLs in each RIL. High oil bulk and low oil bulk will be constructed using extreme RILs and sequenced to identify QTLs controlling oil content by the QTL-seq approaches. These QTLs will be used to confirm the genomic regions of QTLs identified by linkage mapping. Then, the validated QTLs will be used to detect other peanut germplasm and their descendants to explore the different distributions of QTLs for oil content. Elite genotypes with high and stable oil content and their effective diagnostic markers will be developed from the present study. These results will provide fundamental basis of knowledge, techniques and crucial genetic materials for developing novel peanut cultivars with high oil content.

提高含油量是我国花生遗传改良的重要方向之一。前期研究结果表明，花生野生种含油量显著高于栽培种，是改良栽培品种含油量的重要资源。本项目拟以近年来创制的2个含有不同野生种亲缘的高油栽野杂种新种质与低油种质杂交构建的F1、F2和重组近交系（RIL）群体为材料，检测种子含油量，分析栽野杂种高油新种质含油量的遗传特性；通过SNP分析，构建遗传连锁图；通过连锁分析定位含油量相关的QTLs，分析不同QTL之间和QTL与环境之间的关系，明确不同栽野杂种高油新种质含油量QTLs的异同；对RIL群体中极端家系构建的高油池和低油池进行基因组重测序，通过QTL-seq技术定位含油量QTLs，对连锁分析定位的QTLs进行验证；利用所得QTLs检测其他花生亲本和杂交后代，获得含油量高且稳定的种质和分子标记。本项目的开展，将为花生高油育种的亲本选配、后代标记辅助选择和优良高油种质创制提供理论依据和材料基础。

本项目针对我国花生品种含油量总体偏低且不稳定、优质高油资源相对缺乏、含油量遗传基础研究薄弱等问题，利用野生花生含油量显著高于栽培种的特点，分别由两个不同野生种亲缘的高油栽野杂种新种质与低油种质进行杂交组配，获得F1、F2后代及其衍生的重组自交系群体。在三个不同环境下，对两个群体（Z群体和J群体）家系的含油量表型进行了调查。研究结果显示，两个群体家系的含油量表型总体呈现正态分布，不同环境之间表型的相关系数分别为0.46-0.56和0.42-0.50，从中各发现了8份和4份含油量稳定超过55%的家系。多环境下的遗传方差分析显示含油量性状主要受到胚基因型控制,其广义遗传率分别为0.83和0.75。利用基因组重测序技术鉴定Z群体和J群体家系基因型，分别获得了233365个和382569个标记的基因型，进一步构建了包含2802个和2701个重组位点的两张高密度遗传连锁图谱。结合三个环境的表型数据和基因型数据开展了连锁分析和QTL与QTL以及QTL与环境互作分析。两个群体分别在遗传图谱上定位了10个和9个含油量位点，其中包括两个多环境稳定QTL(qZOCB04和qJOCB06)。利用群体家系构建高低油极端混池，采用QTL-seq方法同样检测到qZOCB04的候选区间。根据两个群体双亲的基因组变异信息，在稳定含油量QTLqZOCB04和qJOCB06的目标区间内鉴定到12个和11个候选基因在双亲之间存在非同义突变或者移码突变。针对稳定含油量位点qZOCB04和qJOCB06开发了紧密连锁分子标记InDel_B04和InDel_B06，在花生资源中的高低油材料及其杂交组配后代中，验证了标记的选择效果。组合利用开发的两个分子标记进行辅助选择，最高可以提高含油量2个百分点。本研究结果将为提高分子选择技术效率和培育高油新品种提供理论、技术和材料基础。