背景:疫霉根腐病,全球辣椒生产的主要限制因素,是由土传卵菌引起的,辣椒疫霉.这项研究旨在使用由157个辣椒属组成的小组来检测辣椒基因组中与疫霉根腐病抗性相关的重要区域。基因型。使用源自基因分型测序(GBS)的单核苷酸多态性(SNP)标记进行多位点基因组范围关联研究(GWAS)。用辣椒分离株分别接种个体植物,\'PWB-185\',\'PWB-186\',和\'6347\',在4-8叶期,并在接种后14天内对疾病症状进行评分。疾病评分用于计算疾病参数,包括疾病严重程度指数百分比,百分比的抗性植物,疾病进展曲线下的面积,和估计每个基因型的边际均值。
结果:大多数基因型显示根腐病症状,而5个菌种对所有分离株完全耐药,没有表现出感染症状。来自GBS的总共55,117个SNP标记用于进行多基因座GWAS,其鉴定了330个与疾病抗性相关的显著SNP标记。其中,分布在所有12条染色体上的56个SNP标记在分离株中是常见的,表明与更持久的抵抗力有关。候选基因包括核苷酸结合位点富含亮氨酸重复序列(NBS-LRR),系统获得性耐药(SAR8.2),和受体样激酶(RLKs),在相关标记的0.5Mb内鉴定。
结论:通过开发竞争性等位基因特异性标记(KASP®)进行标记验证,结果将用于提高辣椒对疫霉根腐病的抗性,全基因组选择,和标记辅助育种。
BACKGROUND: Phytophthora root rot, a major constraint in chile pepper production worldwide, is caused by the soil-borne oomycete,
Phytophthora capsici. This study aimed to detect significant regions in the Capsicum genome linked to
Phytophthora root rot resistance using a panel consisting of 157 Capsicum spp. genotypes. Multi-locus genome wide association study (GWAS) was conducted using single nucleotide polymorphism (SNP) markers derived from genotyping-by-sequencing (GBS). Individual plants were separately inoculated with P. capsici isolates, \'PWB-185\', \'PWB-186\', and \'6347\', at the 4-8 leaf stage and were scored for disease symptoms up to 14-days post-inoculation. Disease scores were used to calculate disease parameters including disease severity index percentage, percent of resistant plants, area under disease progress curve, and estimated marginal means for each genotype.
RESULTS: Most of the genotypes displayed root rot symptoms, whereas five accessions were completely resistant to all the isolates and displayed no symptoms of infection. A total of 55,117 SNP markers derived from GBS were used to perform multi-locus GWAS which identified 330 significant SNP markers associated with disease resistance. Of these, 56 SNP markers distributed across all the 12 chromosomes were common across the isolates, indicating association with more durable resistance. Candidate genes including nucleotide-binding site leucine-rich repeat (NBS-LRR), systemic acquired resistance (SAR8.2), and receptor-like kinase (RLKs), were identified within 0.5 Mb of the associated markers.
CONCLUSIONS: Results will be used to improve resistance to
Phytophthora root rot in chile pepper by the development of Kompetitive allele-specific markers (KASP®) for marker validation, genomewide selection, and marker-assisted breeding.