Madeiras das Leguminosae: um estudo anatômico e genético voltado à identificação de espécies

Abstract

Based on the need for better characterization and identification of timber species from Brazil, the group studied anatomical and/or genetic aspects of native species from the Leguminosae family. For this, samples from two populations of Stryphnodendron polyphyllum were selected to verify the existence of intra-specific variability. Seven species of Stryphnodendron were chosen to evaluate the interspecific variability. And nine species of Leguminosae from the Parque Estadual da Ilha Grande (PEIG) were chosen to assess the applicability of genetic identification, being eight of these species subjected to the evaluation of the timber anatomy as a resource to identify them. The botanical material was collected in situ and from a reference timber collection. Traditional methods for timber anatomy were applied and two methods for DNA extraction were used for evaluate them. Anatomical analyses of the S. polyphyllum evidenced an intra-specific variation such as gelatinous fibers, larger sizes radius, fibers of smaller lengths, smaller fibers diameters and smaller diameter of fibers pits for the specimens collected from the Semideciduous Forest affected by the water source. The interspecific variation observed in the genus Stryphnodendron allowed to individualize two of the seven species, S. paniculatum and S. polystachyum, by the type of axial parenchyma and number of cells for the radius length. The species with PEIG occurrence were individualized by: number of cells in the range of axial parenchyma, stratification of cellular elements, prismatic crystals, septated fibers and type of axial parenchyma. An efficient protocol for DNA extraction from timber was established. After optimizing conditions for chloroplast genome markers amplification, the authors selected four microsatellite DNA markers (cpSSR) and two intergenic regions (trnL-F and psbA-trnH). The intergenic spacers were capable to identify eight of the nine species, however the trnF-L was more successful to discriminate the species. The cpSSR markers made it possible to discriminate and identify genetically eight of the nine studied species. Multiple haplotypes were observed for different specimens of Pterocarpus rohrii. Therefore, it can be concluded that the timber anatomy allows the identification of intra-specific variations and among species form different genres. However, the interspecific variation, based on the genus Stryphnodendron, was not fully achieved by the timber anatomical analysis. This result corroborates with previous genetic analysis that point out the clade of multifoliate species with a recent diversification. The existence of multiple haplotypes for Pterocarpus rohrii indicates the need for new taxonomic studies in order to delimit the species. The results of timber anatomy when compared to the genetic results, attest characteristics of secondary xylem as the most conservative among plant parameters and capable to provide strong bases for taxonomic, systematic and phylogenetic studies.