Association mapping in common bean revealed regions associated with Anthracnose and Angular Leaf Spot resistance

ABSTRACT: Despite important biotic stresses to common bean, Anthracnose (ANT) and Angular Leaf Spot (ALS) can cause losses of up to 80 % and occur in more than 60 countries around the world. Genetic resistance is the most sustainable strategy to manage these diseases. Thus, we aimed to (1) identify new SNP markers associated with ALS and ANT resistance loci in elite common bean lines, and (2) provide a functional characterization of the DNA sequences containing the identified SNP markers. We evaluated 60 inbred lines, under field conditions, which represent the elite germplasm developed by the Embrapa common bean breeding program across 22 years, in terms of severity of the ALS and ANT. The lines were genotyped with 5,398 SNPs. Then, a Mixed Linear Model was run to determine the SNP-trait associations. We observed two-significant marker-trait associations reacting to ANT, both located on chromosome Pv-02. These markers explained 25 % of the phenotypic variation. For ALS, only one significant marker-trait association was observed, which is located in chromosome Pv-10 and explained 19 % of the phenotypic variation. These markers, along with others already used, will be useful to add or keep ANT and ALS resistance loci identified in this work in the new carioca and black seeded cultivars.

摘要：尽管普通菜豆面临多种重要生物胁迫，炭疽病（Anthracnose, ANT）与角斑病（Angular Leaf Spot, ALS）可导致最高80%的产量损失，且在全球60余个国家广泛分布。遗传抗性是防控此类病害最具可持续性的策略。为此，本研究旨在实现两大目标：其一，筛选与优良普通菜豆品系中ALS和ANT抗性位点相关的新型单核苷酸多态性（Single Nucleotide Polymorphism, SNP）标记；其二，对携带所鉴定SNP标记的DNA序列开展功能表征。

本研究针对Embrapa普通菜豆育种项目历经22年培育的优良种质资源中的60份自交系，在田间条件下对其ALS和ANT病害严重度进行了评价。采用5398个SNP标记对所有供试品系完成基因分型，随后通过混合线性模型（Mixed Linear Model）开展标记-性状关联分析。

研究结果显示，共检测到2个与ANT抗性相关的显著标记-性状关联位点，均定位于Pv-02染色体，二者可解释25%的表型变异；针对ALS抗性，仅检测到1个显著标记-性状关联位点，定位于Pv-10染色体，可解释19%的表型变异。

本研究鉴定获得的上述标记，结合已有的可用标记，将有助于在新型卡里奥卡型和黑籽型菜豆品种中导入或保留本研究发掘的ANT与ALS抗性位点。