Allelic diversity, phylogeny and population structure of globally collected guava germplasm (Psidium spp.) unveiled through genome-wide g-SSR markers
摘要
Guava (Psidium guajava L.) is an economically and nutritionally important fruit crop, though Indian cultivars possess a narrow genetic base, as most of the cultivars are derived from Allahabad Safeda and its selections. To broaden the genetic base, 78 guava genotypes representing cultivars, selections, exotic/ USDA introductions, and wild species have been collected and conserved in the guava field gene bank at ICAR–IARI, New Delhi. Comprehensive molecular characterization of this germplasm is crucial for effective management, detection of duplicates or misclassified accessions, and for enriching the genetic base to facilitate the development of novel guava cultivars.
ResultsOut of 60 g-SSR markers screened, 44 (73.3%) were polymorphic, generating 187 alleles with an average of 4.25 alleles per locus. The mean gene diversity was 0.58 with observed Heterozygosity was 0.148 and Polymorphic information content (PIC) values ranged from 0.177 to 0.721 (mean 0.52). Neighbour-Joining analysis classified the guava genotypes into three major clusters, effectively separating wild species, indigenously developed cultivars, and USDA introductions. STRUCTURE analysis identified two sub-populations among the studied guava genotypes. AMOVA revealed that the majority of genetic variation (72%) resided among individuals within populations, and PCoA corroborated the clustering pattern. Furthermore, moderate-to-high cross-species transferability of SSRs was observed across the studied wild Psidium species.
ConclusionsThe studied g-SSRs proved effective for efficient genetic characterization of guava germplasm, enabling identification of duplicates, synonyms, and misclassified accessions. The high allelic diversity and distinct clustering of USDA introductions and wild species highlight their potential for enriching the genetic base of guava cultivars. These findings offer important insights to support germplasm conservation, efficient management, and development of future breeding strategies to sustain the guava industry.