Genetic diversity and structure of teak (Tectona grandis L. f.) and dahat (Tectona hamiltoniana Wall.) based on chloroplast microsatellites and Amplified Fragment Length Polymorphism markers

Abstract

Teak (Tectona grandis L. f.) is a tropical forest tree species naturally occurring in India, Laos, Myanmar and Thailand. The closely related dahat (Tectona hamiltoniana Wall.) is an endemic tree species confined to Myanmar. Two chloroplast Simple Sequence Repeat (cpSSR) and sixty-nine Amplified Fragment Length Polymorphism (AFLP) markers were applied to assess patterns of genetic variation in four T. grandis and three T. hamiltoniana populations in Myanmar. The cpSSR analysis confirmed a clear genetic differentiation between species, revealing a single haplotype (H1) in T. grandis, while the three T. hamiltoniana populations were fixed on different haplotypes (H2 or H3). AFLP analysis revealed that genetic diversity varied between species, showing a slightly higher variation in T. grandis than in T. hamiltoniana. The T. hamiltoniana populations showed similar levels of genetic variation, while parameters varied considerably in T. grandis populations. Analyses of Molecular Variance revealed significant genetic differentiation between the two species (38.4 %, p < 0.05) and among populations within species. Genetic variation mainly resided within populations. Significant pairwise genetic differentiation (pairwise F (ST) ) was detected between most populations (p < 0.05). An Unweighted Pair Group Method with Arithmetic Mean dendrogram based on Nei's genetic distances revealed a clear genetic differentiation between species. Diagnostic AFLP markers with complete or nearly complete differentiation between species and complete differentiation at cpDNA markers indicated strong phylogenetic divergence between teak and dahat.