苹果属野生资源遗传多态性及其褐斑病抗性的关联分析

Marssonina apple blotch is one of the most severe apple diseases commonly occurring in arid apple production areas of northwest region. It mainly infects the leaves and leads to premature defoliation of apple tree, thereby affecting the quality and quantity of fruits. Wild apple containing a series of excellent resistance genes is an abundant resource for apple genetic improvement. Nevertheless in the preliminary study we found that different wild apple genotypes showed significant variation of the resistance to marssonina apple blotch. Based on this phenomenon, a Malus wild apple germplasm containing 333 wild apple accessions from 31 Malus species will be investigated in this study. Based on the ABI PRISM 3730 DNA sequencing platform, through scanning of all the accessions from this Malus wild apple germplasm by a set of 20 SSRs evenly distributed across apple genome, the genetic diversity will be analyzed, the relationship and population structure within this large collection of apples will be evaluated and a Malus wild apple core collect will be constructed. Meanwhile, based on the high-throughput 20K SNP Illumina Infinium® array, the whole Malus wild apple core collect will be further scanned to obtain genotypic data. Moreover, an artificial inoculation in vitro assay will be also carried out on this core collection to evaluate their resistance to massonina apple blotch and to get the target phenotypic data. Finally, by using genome-wide association analysis method SNP markers significantly related to the resistance of massonina apple blotch will be identified. The results of this study will provides theoretical foundation for apple molecular assisted breeding, marssonina apple blotch resistance gene separation and genetic improvement of apple resistance to marssonina apple blotch.

苹果褐斑病是西北旱区产地普遍发生且较为严重的病害之一。该病主要危害叶片，引起早期落叶，影响苹果的品质和产量。野生苹果蕴藏有优良的抗病基因，是遗传改良的丰富资源。然而前期研究发现：野生苹果个体间褐斑病抗性差异显著。基于此，本项目拟以31 种333 份野生苹果资源为试材，利用均匀分布在苹果基因组上的 20个SSR，通过ABI PRISM 3730 DNA 测序平台对该资源进行基因分型，从分子水平对其遗传多样性、亲缘关系以及群体结构进行分析并建立苹果属野生资源的核心种质；同时，进一步对核心种质采用20K SNP Illumina Infinium® array进行全基因组扫描以及褐斑病病菌的离体叶片人工接种，最终结合SNP基因型数据与褐斑病抗性表型数据进行全基因组关联分析，探寻与褐斑病抗性性状显著相关的标记位点。研究结果将为苹果的分子辅助育种，褐斑病抗病基因分离以及抗病性状遗传改良提供理论依据。