Microsatellite Analysis to Study Genetic Diversity in Khasi Pine (Pinus Kesiya Royle Ex. Gordon) Using Chloroplast SSR Markers

Pinus kesiya (Khasi pine) is the principal pine species in northeast India having high commercial value. Chloroplast microsatellites (cpSSR) were used to study the genetic diversity and population genetic structure of 10 populations of P. kesiya covering entire natural range of distribution in India. A total of 33 primer pairs (cpSSRs) of P. thunberghii and P. sylvestris were tested in P. kesiya for their transferability, out of which 18 chlo­roplast primers showed positive amplification and 10 were found polymorphic. A total of 250 individuals from 10 different populations were genotyped using the selected 10 cpSSRs. When alleles at each of the 10 loci were jointly analysed a total of 36 size variants were discovered, which combined to desig­nate 90 haplotypes among 250 individuals. None of the haplo­type was found common among the populations as they were population specific. The cpSSR indicated that P. kesiya popula­tions have maintained a moderately high genetic diversity (HT=0.638) which is typical in most coniferous species. Howe­ver, the inter-population genetic diversity was higher than the intra population diversity and the genetic differentiation bet­ween populations was also found to be very high (FST=0.47). A Bayesian cluster analysis separated the populations into six clusters where most of the individuals were found in single population clusters with minor admixtures. The distribution of genetic diversity and sub structuring of P. kesiya reflect week pollen mediated gene flow due to geographic isolation and genetic drift. The study has revealed useful cpSSR markers for P. kesiya, which were lacking earlier and also added an insight into the state of Khasi pine forest in the region, which can be useful for the better management and future conservation programs.