Analysis of genetic diversity of passion fruit (Passiflora edulis Sims) genotypes grown in Kenya by sequence-related amplified polymorphism (SRAP) markers

Passion fruit (Passiflora edulis [Sims]) is currently ranked third among fruit exports from Kenya and has great potential since demand for both fresh fruit and processed juice is on a continuous increase. Although assessment of genetic variability of germplasm is indispensable for improvement and development of superior cultivars, little information is available on the genetic diversity of passion fruit cultivated in Kenya. The objective of this study was to determine the genetic diversity of passion fruit genotypes from major growing regions in Kenya using sequence-related amplified polymorphism (SRAP) markers. Twenty four SRAP primer combinations were screened using three passion fruit genotypes and only seven that displayed polymorphic and stable amplification profiles were used to analyze 22 genotypes. The seven primer combinations amplified a total of 931 clear bands with an average of 133 bands per primer pair, of which 610 (65.5%) bands were polymorphic. The similarity coefficients among the 22 passion fruit germplasms ranged from 0.51 to 1.0 with an average of 0.755. The 22 passion fruit genotypes were classified into two groups by cluster analysis using unweighted pair-group method with arithmetic mean (UPGMA) with 12% similarity. Shannon's diversity index was 0.0934 and Nei's gene diversity index was 0.1370 in the present study. The study findings demonstrate the existence of a considerable amount of genetic variability among passion fruit genotypes grown in different regions of Kenya. This indicates the potential application of these genotypes in breeding programs by exploiting the use of molecular markers for selection of specific agronomic traits.