Current Genetic Structure of Teak (Tectona Grandis) in Myanmar Based on Newly Developed Chloroplast Single Nucleotide Polymorphism and Nuclear Simple Sequence Repeat Markers

Teak ( Tectona grandis), which is among the most valuable tropical timber species, is under pressure from rapid deforestation and habitat fragmentation. Limited genetic information is available for Myanmar teak, which comes from the largest natural teak-bearing forest area in the world. To determine the phylogeographic patterns of Myanmar teak, we evaluated three newly developed chloroplast single nucleotide polymorphism (cpSNP) and 10 nuclear simple sequence repeat (nrSSR) markers in 480 individuals representing 20 natural populations. The cpSNP markers detected four haplotypes, each differing by a single mutation. The GST value was lower than the NST value and did not reveal a phylogeographic structure of Myanmar teak. Nuclear microsatellite analysis revealed high genetic diversity with the mean expected heterozygosity (0.652). The same level of genetic differentiation (4%) was observed for both cpSNP and nrSSR markers in different groups. Conservation of the HMB, TDG, KTA, and POL populations should receive highest priority because these contribute most to the total genetic diversity. The genetic boundaries of teak observed from combining the results of cpSNP and nrSSR marker barriers suggested four potential zones in the teak seed transfer guidelines of Myanmar. In light of our findings, we discussed appropriate gene conservation strategies and proposed seed zones to safeguard the current genetic resources of Myanmar teak.