MOLECULAR CHARACTERIZATION AND GENETIC RELATIONSHIPS AMONG SUMMER SQUASH (CUCURBITA PEPO L.) GENOTYPES VIA SSR PROFILING

Uzma Maqbool, Asima Amin*, Baseerat Afroza, Gowhar Ali, Nageena Nazir, Parveez Ahmad Sheikh, Ishfaq Abidee, Spinder Jeet Kour

Genetic diversity is a crucial prerequisite for effective crop improvement and the development of high-yielding, climate-resilient cultivars of summer squash (Cucurbita pepo L.). The present study assessed molecular genetic variability and genetic relationships among forty diverse summer squash genotypes using simple sequence repeat (SSR) markers. Genomic DNA extracted from young leaf tissues was amplified with eighteen SSR primer pairs, generating reproducible and polymorphic banding patterns. A total of thirty-nine alleles were detected across all loci, with alleles per locus ranging from one to three and an average of 2.16, indicating moderate allelic diversity within the germplasm. Polymorphic information content (PIC) values varied from 0.0476 to 0.3693, with a mean of 0.2977, reflecting the moderate to high informativeness of the SSR markers. Cluster analysis based on genetic distance grouped the genotypes into three major clusters, revealing substantial genetic differentiation. While several genotypes showed close genetic similarity, distinct accessions such as SKUA-SQ-10 and SKUA-SQ-20 exhibited marked genetic divergence, highlighting their potential utility as parental lines in breeding programmes. The clustering pattern showed no strict association with genotype origin, suggesting historical gene flow and shared ancestry. Overall, the study confirms the effectiveness of SSR markers for genetic diversity assessment and provides valuable molecular insights to support germplasm conservation, parental selection and strategic hybridization for genetic improvement of summer squash.