Abstract Chili pepper (Capsicum annuum L.) is one of the most important vegetable crops, largely suffers from various biotic stresses, including Phytophthora capsici L., imposing huge yield loss. Due to the lack of agronomically superior traits in available resistant accessions, chili breeders are constantly searching for new sources of resistance with genetically diverse traits. In the present study, a total of 233 chili pepper accessions from Ethiopia and India were screened under P. capsici infection. A total of 22 highly resistant and 17 moderately resistant accessions were identified. Among these, only 32 chili pepper accessions with mean disease index ranging from 1.4 to 2.0 and 2.20–3.8, were selected for genetic diversity analysis. From a total of 19 SSR primers analyzed, only 14 SSR primers were shown to be polymorphic. The result showed that a total of 31 alleles with an average of 2.214 alleles per primer were amplified across the selected accessions. A maximum of 3 alleles were observed in only 3 SSR primers. The analysis of 14 SSR primers resulted in PIC values ranging from 0.12 to 0.98 with an average of 0.64, the percentage of polymorphic loci of 11.45–96.87% with an average of 57.69% and effective number of alleles (Ne) of 1.058–2.174 with a mean of 2.213. This indicated that the 14 SSR primers detected variation among 32 chili pepper accessions. The genetic dissimilarity index (GDI) value ranged from 0.05 to 0.51, with the highest GDI (0.51) in Gutowayu_80039 and IC_537646 accessions. The population structure and cluster analysis grouped the chili pepper accessions into three genetic resistance groups. In addition, the UPGMA cluster analysis of the 14 SSR primers clearly distinguished between one resistance group and the other. As per AMOVA analysis, a total of 42% and 58% of variation among and within populations were detected in the nine populations of C. annuum, respectively. The resistance/moderate resistance accessions greatly showed both phenotypic and genotypic variation. The accessions GojamMecha_9082, Mareko_233636, GojamMecha_9086, IC_526851, and IC_537587 showed high level of resistance with diversified resistance loci, which could be used as a source of resistance for chili pepper breeders.

中文翻译：

---

辣椒疫霉 (Phytophthora capsici) 感染下辣椒 (Capsicum annuum L.) 的表型特征及使用 SSR 标记分析已鉴定抗性种质的遗传多样性

摘要 辣椒（Capsicum annuum L.）是最重要的蔬菜作物之一，受到包括辣椒疫霉（Phytophthora capsici L.）在内的多种生物胁迫的影响，造成了巨大的产量损失。由于可用抗性种质中缺乏农艺上的优越性状，辣椒育种者一直在寻找具有遗传多样性性状的新抗性来源。在本研究中，共筛选了来自埃塞俄比亚和印度的 233 份辣椒种质。共鉴定出 22 个高度抗性和 17 个中等抗性种质。其中，仅选择平均病害指数在 1.4 至 2.0 和 2.20 至 3.8 之间的 32 个辣椒种质进行遗传多样性分析。从总共分析的 19 个 SSR 引物中，只有 14 个 SSR 引物被证明是多态的。结果表明，在选定的种质中总共扩增了 31 个等位基因，每个引物平均有 2.214 个等位基因。仅在 3 个 SSR 引物中观察到最多 3 个等位基因。对14条SSR引物进行分析，PIC值范围为0.12~0.98，平均为0.64，多态位点百分比为11.45~96.87%，平均为57.69%，等位基因有效数（Ne）为1.058~2.174，平均值为 2.213。这表明 14 个 SSR 引物在 32 个辣椒种质中检测到变异。遗传差异指数（GDI）值范围为0.05~0.51，其中Gutowayu_80039和IC_537646种质的GDI值最高（0.51）。种群结构和聚类分析将辣椒种质分为三个遗传抗性组。此外，14 个 SSR 引物的 UPGMA 聚类分析清楚地区分了一个抗性组和另一个。根据 AMOVA 分析，在 C. annuum 的 9 个种群中分别检测到种群间和种群内总共 42% 和 58% 的变异。抗性/中等抗性种质极大地显示了表型和基因型变异。GojamMecha_9082、Mareko_233636、GojamMecha_9086、IC_526851和IC_537587等种质表现出高水平的抗性，具有多样化的抗性位点，可作为辣椒育种者的抗性来源。抗性/中等抗性种质极大地显示了表型和基因型变异。GojamMecha_9082、Mareko_233636、GojamMecha_9086、IC_526851和IC_537587等种质表现出高水平的抗性，具有多样化的抗性位点，可作为辣椒育种者的抗性来源。抗性/中等抗性种质极大地显示了表型和基因型变异。GojamMecha_9082、Mareko_233636、GojamMecha_9086、IC_526851和IC_537587等种质表现出高水平的抗性，具有多样化的抗性位点，可作为辣椒育种者的抗性来源。