Molecular diversity and genetic relationships of Sri Lankan pomegranate (Punica granatum L.) landraces assessed with Inter Simple Sequence Repeat (ISSR) regions
7 February 2017
Attanayake, Rekha ; Kumari , Sarojani ; Weerakkody, Palitha ; Rajapaksha, Ranil; abdamania@ucdavis.edu, Ardeshir; Bandaranayake, PradeepaPomegranate (Punica granatum L.) was first introduced to Sri Lanka, possibly through ancient trade routes, over thousands of years ago. However, there is no information about the diversity of the germplasm in the country, which is important, both, for breeding new varieties and for conservation efforts. In the current study, Inter-simple sequence repeat (ISSR) regions were used to investigate the genetic diversity and population structure of pomegranate on the island of Sri Lanka. Hundred and twenty accessions representing seven populations from all pomegranate growing regions of the country were analyzed using 20 ISSR primers. A total of 107 loci were amplified with the average polymorphism information content of 0.3. While the average inter-population genetic distance was 0.141, it was 0.149 between populations, exhibiting medium genetic distance, both within and among populations. The analysis of molecular variance and Nei’s genetic diversity revealed higher genetic variation within populations than among populations. A lower genetic differentiation (GST) was observed in pair-wise comparison of populations, further suggesting little variation between them. A considerable level of gene flow (Nm) was reported among these populations, irrespective of the geographical affiliations. Clustering pattern of the populations was also in agreement with above analysis and suggest human involved genetic migration and exchange patterns. The Unweighted Pair Group Method with Arithmetic Mean (UPGMA) dendrogram and Principal Component Analysis clustered the pomegranate accessions into two main clusters with several sub-clusters. While clustering did not show any relationships with the geographical origins, all red peeled accessions clustered into a small sub-cluster suggesting sharing of common ISSR regions among them. The results indicate that the ISSR variability is sufficiently informative and powerful to assess genetic diversity of P. granatum landraces in Sri Lanka.