ASSESSMENT OF GENETIC DIVERSITY IN THE SACCHARUM GERMPLASM OF SRI LANKA

Abstract

Two hundred accessions of Saccharum germplasm repository of Sri Lanka were assessed for genetic diversity using 23 SSR primers. The accessions comprised typical Saccharum officinarum, Sacchurum spp. hybrids, Saccharum spontaneum and Erianthus arundinaceous.
Similarity matrix and dendrogram were constructed using the NTSYS pc 2.2. The values of polymorphic information content (PIC) were calculated for each primer to evaluate their efficiency. Based on genetic distances, analysis of molecular variance (AMOVA), principal coordinate analysis, Nei's gene diversity, Shannon's information index, number of polymorphic loci and their percentages for different types of accessions were performed to assess genetic relationship using GenAlEx-6, -6.5 and Popgene-1.31. A total of 439 SSR alleles were scored for tested primers. At the genetic similarity coefficient of 79%, the accessions were classified into four major clusters.
The genetic similarity among accessions ranged from 0.957 to 0.665. The average PIC value of primers was 0.926. AMOVA confirmed that the variation of the accessions within population was higher (84%) than between populations (16%). Based on the results of principal coordinate analysis, the accessions clustered into 3 major groups: i). hybrids imported from Pakistan, ii). Erianthus arundinaceous with all other hybrids and iii). Saccharum officinarum with Saccharum
spontaneum. Almost similar clustering pattern of accessions was obtained from principal coordinate analysis and dendrogram based on similarity indices. The highest Nei's gene diversity and Shannon's information index values confirmed that high genetic diversity observed within imported sugarcane hybrids. The information derived from this study is important in devising mating systems for maximizing efficiency of sugarcane breeding in Sri Lanka.