Genetic diversity of improved genotypes of Tectona grandis in the state of Mato Grosso, Brazil
Teak (Tectona grandis) is a tree species native to South-east Asia and widely cultivated in Latin America. In Mato Grosso state, Brazil, teak is the second-most planted forest species due to its high productivity resulting from high adaptability to the soil and climate conditions of the region. However, there is little information about the genetic diversity of improved genotypes cultivated in the state. Thus, the objective of this study was to quantify, through ISSR (inter-simple sequence repeat) molecular markers, the genetic diversity of improved teak genotypes used in different plantations in Mato Grosso state. For this, 31 ISSR primers were tested on 113 genotypes separated into nine populations. Six primers were selected to perform the analyses, resulting in 55 amplified loci. All selected primers showed a high polymorphic information content. Considering all genotypes in the Mato Grosso population, the percentage of polymorphic loci (P) was 96.4%, the genetic diversity according to Nei՚s genetic diversity index (H) was 1.96, and according to Shannon՚s information / diversity index (I), it was 0.53. Considering each population individually, P varied from 50.9% to 90.9%, H from 0.21 to 0.33, and I from 0.30 to 0.49. Most of the genetic diversity observed was within populations (86%). Four genetic groups were identified, with a high level of admixture among them. The existence of a considerable genetic diversity within populations indicates the possibility of exploring this variation in genetic improvement programmes. However, the introduction of new genetic materials is recommended to increase the genetic base of this species in Brazil.