ISSR markers for analysis of molecular diversity and genetic structure of Indian teak (Tectona grandis L.f.) populations

Inter simple sequence repeats (ISSR) constitute a powerful dominant DNA molecular marker system used for diversity analysis, which is indispensable for making estimates of genetic base and demarcation of populations for undertaking conservation and improvement program of forest tree species. Twenty nine populations of teak (Tectona grandis L.f.) were collected from central and peninsular India for analysis of genetic diversity and structure. Genomic DNA from ten randomly selected individuals of each population was extracted and amplified using five ISSR primers (UBC-801, 834, 880, 899 and 900). The primers showed 100% polymorphism. UBC-900 recorded the highest Nei's genetic diversity (0.32 to 0.40) and UBC-899 had the highest Shannon's Information Index (0.49 to 0.59). AMOVA revealed a very high intra-population genetic diversity (91%), in comparison to inter-population genetic diversity among states (6.17%) and within states (2.77%) which were also indirectly confirmed by large standard deviations associated with genetic diversity estimates for individual population, as well as poor bootstrapping values for most of the cluster nodes. However, UPGMA dendrogram revealed several clusters, with populations from central India being present almost in each cluster, making groups with populations of adjoining states and distant states. Nevertheless, the cluster analysis distinguished the drier teak populations of central India from the moist teak populations of south India, which was also confirmed by Principle Coordinate Analysis. The findings advocates the need not only for enhancing selection intensity for large number of plus trees, but also for laying out more number of in situ conservation plots within natural populations of each cluster for germplasm conservation of teak aimed at improving the teak productivity and quality in future.