Assessment of genetic diversity in Pithecellobium dulce (Roxb.) Benth. germplasm using RAPD and ISSR markers

Key message Pithecellobium dulce has a huge repository of morphological and genetic diversity within the species which has been documented for further tree research and breeding programmes. A total of 40 accessions of a multipurpose leguminous tree, Pithecellobium dulce, differing in morphological and phenological characteristics was collected from different locations in Rajasthan and genetic diversity assessed using random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) markers. Out of 60 RAPD primers, 43 decamer primers produced 311 scorable bands of which 223 bands were polymorphic. Polymorphic banding patterns with the number of amplified fragments varied from 1 (OPA-12 and OPF-17) to 12 (OPF-04, OPT-07, OPT-17, OPT-20). Percent polymorphism ranged from 33.3 % (OPF-07, OPA-20, OPT-05) to 89 % (OPA-13) with an average of 64.34 %. Out of the 20 ISSR primers screened, 8 primers produced 77 amplification products of which 55 were polymorphic. The number of bands amplified per primer varied between 6 (UBC-820) and 13 (UBC-808 and UBC-816) with average band size between 300 and 4,500 bp. Percent polymorphism ranged from 38 % (UBC-817) to 100 % (UBC-811) with an average of 71 %. Dendrogram constructed on the basis of combined RAPD and ISSR markers separated the accessions into five distinct clusters at 53 % variation with Jaccard's similarity coefficient ranging from minimum similarity (0.35) between Karoli (K) and Malviya Nagar, Jaipur (MN1) to maximum similarity (0.81) between two populations of Kota (K1 and K2). The matrices for two markers, RAPD and ISSR, were also compared using Mantel's test. The correlation value between the matrices is high (r = 0.83) indicating good correlation between the two molecular marker systems. The study indicated a high level of morphological and genetic diversity in P. dulce.