Tectona grandis: Narrow Genetic Base? A New Perspective on the Genetic Variability of Teak

Abstract

Teak (Tectona grandis Linn. f.) is considered one of the most expensive hardwoods in the world. The dispersion of the species over the years has taken the teak beyond its origin centers and little is known about the genetic origin and genetic variability. This study aimed to investigate the genetic diversity and population structure existing in a teak germplasm bank collection in Brazil. DNA was extracted from young leaves and each sample were genotyped by whole genome sequencing at 8x of coverage, the sequencing were aligned using the genome at NCBI, and SNPcalls and quality control were made. To study the population structure of the genotypes, Bayesian variational inference was used via fastStructure, the phylogenetic tree was based on the modified Euclidean distance and the clustering by the UPGMA hierarchical method. Genetic diversity was analyzed based on the pairwise genetic divergence (Fst) of Weir and Cockerham. Genotyping by sequencing resulted in a database of approximately 1.4 million of variations SNPs were used for analysis. It was possible to identify four subpopulations with genetic variability between and within the subpopulations, so this study made it possible to confirm the existence of genetic variability in teak, contrary to what was expected.