Genetic variation and origin of teak (Tectona grandis L.f.) native and introduced provenances

A total of 420 individuals belonged to 18 native teak (Tectona grandis L.f.) provenances from all four distributed countries and 10 introduced provenances were analyzed to for genetic variation, structure and genetic origin using SSR markers. The unbiased gene diversity for each provenance ranged from 0.4692 to 0.8523 with a mean value 0.6612, showing high variation within teak provenances and variation in India provenances was highest than in other countries' provenances. AMOVA analysis showed that the majority of variation existed within provenances (84.760%) and also substantial variation among countries (10.586%). As more as possible plus trees from large population should be selected or conserved in order to keep genetic variability for future improvement. Different countries populations should be preserved in the natural habitat or collected for ex site conservation with cooperation and region-wise strategies. A Mantel test revealed significant correlation between genetic distances and geographic distances of teak provenances (R.0.7355, P <0.001). The cluster analyses by UPGMA, PCA and STRUCTURE methods gave very similar results, showing India provenances were firstly differentiated, and Laos provenances clustered with Thailand provenances, then introduced provenances and Myanmar provenances successively joined in the clusters. The introduced provenances no. 19, 20, 22, 23, 25, 27 and 28 appeared to be very closely linked to Laos provenances (especially no. 17) and Thailand provenances (especially no. 5 and 6), while provenances no. 21, 24, 26 may be originated from Myanmar provenance (especially no. 16).