小麦产量构成因子的杂种优势位点发掘与杂种优势群构建

Increasing grain yield is a long-term goal in crop breeding to meet the demand for global food security. Utilization of heterosis is an effective way to increase wheat yield. Molecular markers have been widely used to predict heterosis studies. However, there is little research about genome-wide prediction of heterosis in wheat hybrid. Based on the previous molecular clustering of 175 domestic and foreign wheat cultivars such as BNS and BNS366, multiple hybrid population (MHP) was constructed using 449 hybrid F1 resulting from 31 representative wheat cultivars by diallel and NCⅡ design. Field experiments were carried out across two different environments. In this study, we will study genome-wide prediction for heterosis comprising the following. First, the combining ability and heterosis will be evaluated using a phenotypic wheat dataset comprising 449 hybrids and their 31 parents; Second, the 31 parental lines used to develop the MHP will be genotyped by an Axiom® wheat 660K SNP chip, and the genotypes of hybrids can be deduced by their parental lines; Third, the heterotic groups of BNS hybrid wheat will be constructed by whole genomic molecular cluster analysis; Fourth, genome-wide association studies (GWAS) will be used to identify heterotic loci for yield related traits based the genotypes of MHP. This study provides key molecular markers for the selection of parents of hybrid wheat, and important reference for polygenic pyramiding and gene cloning of heterotic loci.

为保障全球粮食安全，不断提高粮食作物产量是育种工作的长期目标。杂种优势利用是提高小麦产量的有效途径。分子标记已经广泛用于预测杂种优势研究。但是，很少有关小麦杂种优势的全基因组预测报道。在前期不育系BNS和BNS366等175份国内外小麦品种分子标记聚类基础上，我们选取不同生态区的31份小麦品种为亲本，采用双列杂交设计组配449个组合，组成多杂种群体，已鉴定2年产量构成因子田间表现。本研究拟利用杂种群体开展杂种优势的全基因组预测；1）评价3年2点的产量相关性状配合力效应和杂种优势；2）利用高通量SNP芯片检测31个亲本的全基因组基因型，推导多杂种群体的基因型；3）通过分子聚类分析构建BNS型杂交小麦杂种优势群；4）利用全基因关联分析（GWAS）发掘杂种优势和F1产量构成因子显著关联的SNP。这为杂交种的亲本选配提供有效分子标记，也为分子标记聚合杂种优势相关基因位点及基因克隆提供重要参考。

本研究在小麦上开展了基于多杂种群体（multiple hybrid population，MHP）的全基因组关联分析（Genome-wide association studies，GWAS）研究，采用包括低温敏不育系BNS和BNS366的30个小麦品种（系），通过双列杂交和NCII配制了419个杂种F1的多杂种群体。通过评价三个环境的多杂种群体产量相关性状、配合力效应和杂种优势分析，并结合亲本和杂交种的高通量SNP分子聚类结果构建了BNS型杂交小麦杂种优势群；结合660K小麦SNP芯片产生的多杂种群体的基因型数据和产量相关性状采用rMVP软件进行GWAS分析，鉴定出与杂交种产量性状和中亲优势显著相关的195个SNP位点，尤其是单株穗数和千粒重中亲优势显著关联的SNP中有7个QTL簇(QTL clusters)。这为杂交种的亲本选配提供有效分子标记，也为聚合杂种优势相关基因位点及基因克隆提供重要参考。