基于连锁作图与关联分析发掘辣椒疫病抗性基因

Identification on resistance genes is an important basis of crop resistance genetic improvement. Phytophthora blight in pepper is caused by Phytophthora capsici Leonian, causing severe damage to Capsicum crops, and the disease occurs widely in pepper cultivation areas in the world. The genetic mechanism of resistance of pepper to the disease is complex. In this study, we will conduct both linkage mapping and association analysis to overall dissect the variation of the resistant traits and identify the resistance genes (QTLs) to P. blight based on resistance identification and genotyping with genome-wide SSR markers. The linkage mapping was based on a RIL population (F6, n=201) developed from 'C. annuum V06C1720'(susceptible) × 'C. annuum V06C1825' (resistant) cross, and the association mapping was applied to 405 accessions of the primary core collection. SSR markers tightly linked to P. blight resistance gene will be screened and the excellent alleles having potential value in pepper breeding and their carrier materials will be identified from the research. The study will lay solid foundation for the molecular marker-assisted breeding, resistance genes cloning and resistance genetic improvement in pepper.

抗病基因发掘是农作物抗性遗传改良的重要基础。辣椒疫病（Phytophthora blight）是由疫霉菌（Phytophthora capsici L.）侵染引起的一种毁灭性辣椒病害，其抗性遗传机理复杂。本研究以项目组基于'C. annuum V06C1720'（高感）× 'C. annuum V06C1825' （高抗）构建的RIL（F6，n=201）为连锁作图群体、辣椒初级核心种质（n=405）为关联分析群体，在系统开展疫病抗性鉴定和SSR标记全基因组扫描基础上，联合应用连锁作图和关联分析方法，全面剖析辣椒疫病抗性变异，发现并精细定位辣椒疫病抗性基因（QTLs），获得紧密连锁的SSR分子标记，挖掘具有潜在育种价值的优异等位变异及其载体材料。研究结果将为辣椒疫病抗性分子标记辅助选择育种、抗性基因克隆以及抗性遗传改良奠定坚实基础。

本研究以'C. annuum V06C1720'（高感）× 'C. annuum V06C1825'（高抗）构建的RIL为连锁作图群体、辣椒核心种质为关联分析群体；基于SSR标记技术，获得CM0005c、ge35-141pmH0135Cd和Hpms1-139c等12个疫病抗性优异等位变异，其表型贡献率为2.94%~21.29%；发掘出种质55、65、161、171、132、91、106、125、127、169、170等优良疫病抗性载体材料；利用RIL和GBS技术，构建了总长2010.48cM，标记间距为0.23cM的辣椒SNP分子永久遗传图谱；应用该图谱检测到疫病病株率、病情指数等相关QTLs 19个，分布于辣椒第1、4、6、10染色体上，加性效应在-13.24~26.96，解释的表型变异从189.61%~ 722.23%，其中，14个QTLs分布于4号染色体232.30 cM ~248.40 cM 区域。研究结果为辣椒疫病抗性分子标记辅助选择育种、抗性基因克隆以及辣椒抗性遗传改良奠定了基础。