Genetic and Molecular Architecture and Character Association Analysis in Papaya (Carica Papaya L.)

Abstract

The study was conducted at the Horticulture Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, using a line x tester mating design involving fourteen papaya genotypes (ten lines and four testers). The analysis revealed significant genetic variation among key traits, with high genotypic and phenotypic coefficients of variation (GCV and PCV) observed for fruit yield per plant, number of fruits per plant, and fruit weight. This indicates substantial genetic diversity and environmental influence on these traits, suggesting strong potential for improvement through selective breeding. Traits like fruit yield per plant showed a high genetic advance percentage (93.16%), making them prime candidates for enhancement in future breeding programs. Correlation studies revealed that traits such as fruit weight, fruit diameter, and pulp thickness have strong positive relationships with fruit yield, implying that selecting these traits can directly improve yield. Path coefficient analysis further identified days to flowering and plant height as having significant direct effects on fruit yield, providing valuable targets for selection. The study also examined genetic diversity using SSR markers. Out of 20 SSR primers tested, 13 were polymorphic, resulting in a polymorphism percentage of 65%, indicating a high level of genetic variation among the genotypes. Primers such as CP05 and CP98 showed the highest polymorphism, with CP05 demonstrating no amplification in six genotypes, while CP98 exhibited two distinct bands in Co-7 and Red Indian. The Polymorphism Information Content (PIC) value averaged 0.45, reflecting moderate marker informativeness. Dendrogram analysis clustered the genotypes into three major groups, highlighting different genetic similarity patterns. Cluster 1 included closely related genotypes like Arka Prabhat and Dwarf Lily, suggesting common genetic traits. Cluster 2 had moderate genetic similarity, indicating potential for combining diverse traits in breeding programs. Cluster 3 comprised genetically distinct genotypes like Pant Papaya-2 and Coorg Honeydew, offering valuable genetic diversity for introducing novel traits into breeding efforts. Overall, this study provides comprehensive insights into the genetic diversity and potential for trait improvement in papaya, using both quantitative trait analysis and molecular markers. The findings offer a valuable resource for breeders aiming to enhance fruit yield, quality, and other agronomic traits in papaya breeding programs.