GENETIC CHARACTERIZATION AND BIOCHEMICAL ASSAY OF PASSION FRUIT (Passiflora edulis Sims) VARIETIES GROWN IN SELECTED REGIONS OF KENYA FOR DROUGHT TOLERANCE

Abstract

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 and biochemical characterization of germplasm for drought tolerance is indispensable for improvement and development of superior cultivars, little information is currently available on the genetic diversity and drought tolerance of passion fruit cultivated in Kenya. The objective of this study was to determine the genetic diversity of passion fruit varieties from passion fruit growing regions in Kenya using sequence-related amplified polymorphism (SRAP) markers and to characterize the varieties for drought tolerance. Twenty two passion fruit varieties were analyzed with 24 pairs of SRAP primers. Seven out of 24 pairs of SRAP primers displayed polymorphism and stable amplification profiles. A total of 931 clear bands were amplified 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 varieties were classified into two groups by cluster analysis using unweighted pair- group method with arithmetic mean (UPGMA) with 12% similarity. Shannon’s diversity index (SDI) was 0.0934 and Nei’s gene diversity index (NGDI) was 0.1370 in the present study. The study findings demonstrate the existence of genetic variability among passion fruit varieties grown in different regions of Kenya. This suggests the potential application of these varieties in breeding programs by exploiting the use of molecular markers for selection of specific traits.