Caracterização da diversidade genética de Teca (Tectona grandis) de diferentes procedências usando marcadores microssatélites / Characterization of genetic diversity of teak (Tectona grandis) from different provenances using microsatelliate markes

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Teak (Tectona grandis) is one of the main timber species in the world with high economic value, famous for its beauty, strength and durability. The species occurs naturally in India, Myanmar, Thailand, Laos and Indonesia, where diversity studies have been conducted with regard to the conservation of genetic resources. However, there is a need for studies of genetic diversity of teak in Brazil that could be used mainly for the protection of plant varieties and for breeding. Therefore, the objective of this study was to characterize the genetic diversity of teak genotypes used in Brazilian plantations. We tested 10 microsatellite primers, obtained in the literature, to assess 60 teak genotypes, 33 genotypes from seeds of plantations in Caceres, 14 clones obtained in Caceres and 13 clones originated from Honduras, Malaysia, India, Indonesia, Ivory Coast and Solomon Islands. The genotypes were divided in eight groups, in accordance to its origin, for the genetic diversity analysis. Multivariate analysis were conducted using the Bayesian method implemented in the program STRUCTURE, as well as cluster and principal coordinates analysis. Of the 10 primers tested, 9 showed polymorphism, and were then used for statistical analysis. High genetic variability for the teak genotypes was detected, with the average number of alleles per locus equal to 5.22. Caceres genotypes showed 100% polymorphism, followed by the clones from India with 90% polymorphism. The average observed heterozygosity ( o = 0.352) was lower than the average expected heterozygosity ( e = 0.443). Consistent with other studies in teak, most of the genetic variability was concentrated within groups (Hs = 0.436). With the analysis of the STRUCTURE software it was possible to define the division of the genotypes into three groups, 73.4% placed in one group (red) represented the majority of the genotypes of Caceres, and 13.3% allocated in the green group composed of some clones from India, a clone from Solomon Islands, Malaysia and Honduras and the clones of the Ivory Coast. The 13.3% of the remaining genotypes possessed a mixture of the two groups (red and green). Cluster analysis using Jaccard index indicated the separation of the genotypes into six distinct groups: group I belonging to the clone from Indonesia, group II having two clones from India, group III with genotypes from Caceres and two clones from India and Malaysia, group IV having the Honduras and Malaysia genotypes, group V with clones from India and group VI with clones belonging to the Ivory Coast and the Solomon Islands. This result was consistent with the principal coordinate analysis. From the results described above, together with the cluster analysis using Neis distance, it was possible to infer two probable origins of teak implemented in Brazil: India and Malaysia. After assessing the genetic divergences, suggestions were made concerning the use of contrasting genotypes as parents in breeding programs.

ASSUNTO(S)

crop protection teca variação genética. genetic diversity. plant breeding proteção de plantas melhoramento genético marcador molecular molecular markers teak

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