Rapid Identification of Candidate SNPs and QTLs for Capsicum annuum Chili Fruit Size and Capsaicin Content Using...

Fruit size and pungency are key yield and quality traits in chili. This study combines high-throughput genotyping with bulk segregant analysis (BSA) to identify candidate SNPs and quantitative trait loci (QTLs) by analyzing extreme phenotypes from a Ghotki × Chakwal-4 F2 population. The traits were fruit length, diameter, length-to-diameter ratio, and weight, along with capsaicin content. Significant correlations were observed among length, diameter, and length-to-diameter ratio. A total of 534 single nucleotide polymorphisms (SNP) markers were used to develop genetic maps from 4315 to 6607 cM long. The SNP frequency data was pooled for the 25% of individuals showing extreme values for each measured trait, and bulk segregant analysis (BSA) was performed. BSA identified high-scoring SNPs associated with pungency (SNP 1_41308232; SNP 12_104377148), fruit length (SNP 1_92509300; SNP 6_218780813), and fruit weight (SNP 6_100989762 and SNP 6_138660974). Genetic mapping identified twelve pungency QTLs, three for fruit length, two for fruit diameter, two for the length-to-diameter ratio, and thirteen for fruit weight. Overlapping QTL regions on chromosome 6 influence fruit length, fruit width, and capsaicin content, indicating potential pleiotropy and offering promising targets for multi-trait selection in chili breeding. The study identifies key SNPs and QTLs that simultaneously influence chili fruit size and pungency, providing valuable targets for multi-trait breeding.