Assessment of genetic diversity in Shorea robusta: an economically important tropical tree species

Abstract

The present investigation reports an elucidation of genetic diversity among four-populations of most economically and ecologically important tree species, sal (Shorea robusta Gaertn.) for the first time in India, using ISSR markers. A total of one-hundred individual S. robusta trees were sampled from four different populations, considering twenty-five individuals from each population. In total, twenty-ISSR primers were screened with S. robusta DNA, and out of twenty, sixteen-primer produced reproducible amplicons. Sixteen selected ISSR markers were amplified a total of 118 alleles and the total number of amplicons for individual primers ranged from 5 to 12, with a mean of 7.37 alleles per primer, of which 74 were polymorphic with an average of 4.62 alleles per primer. The ISSR primer (GA)8YG yielded highest number of alleles (12) and primers (CA)8RG and (CT)8G yielded lowest number of alleles (5), with an average alleles size between 200-3500bp. The percentage of polymorphic alleles ranged from 40 [(CA)8RG] to 83.33 [(AC)8C]. A dendrogram based on UPGMA analysis grouped the four populations into two major clusters, having Keonjhar population into first cluster and rest three populations into second cluster. It was notable that the second major cluster was further divided into three-separate sub-clusters, representing population from each three locations. Analysis of molecular variance (AMOVA) revealed that the majority of genetic variation exists within populations, compared to the variation that exists among the populations. The present study is a clear-cut indication that inter- and intra-population genetic variation exists in S. robusta and ISSRs appears to be an efficient marker system in quantifying genetic variability in different populations of S. robusta.