Genetic diversity of Schizolobium parahyba var. amazonicum (Huber ex. Ducke) Barneby, in a forest area in Brazil.

Schizolobium parahyba var. amazonicum (Fabaceae) is an arboreal species, endemic to the Amazon Rainforest, popularly known as paricá. It is used on a commercial scale in the timber sector, pulp and paper production, reclamation projects in degraded and landscaped areas. However, there is no availability of genetically improved material selected for the environmental conditions of the State of Espírito Santo, Brazil. In this sense, the present study aimed to characterize the genetic diversity in a population of S. amazonicum, established in a forest area in the southern region of the State of Espírito Santo, using inter-simple sequence repeat (ISSR) molecular markers. DNA samples from 171 individuals were analyzed using 11 ISSR primers, which generated 79 polymorphic bands in a total of 136 fragments (58%). The polymorphic information content performed for the ISSR markers revealed a mean of 0.37, classifying them as moderately informative. The number of loci found (N = 79) was greater than that established as the optimal number (N = 69) for the analyses. High genetic diversity was found with the parameters, genetic diversity of Nei (HE = 0.375) and Shannon index (I = 0.554). The data demonstrated in the dendrogram, based on the UPGMA cluster analysis, corroborated by the Bayesian analysis performed by the STRUCTURE program, which indicated the formation of two distinct clusters (K = 2). One of the groups was formed with the majority of the individuals (153 genotypes) and the second with the minority (18 genotypes). The results revealed high genetic diversity in the population of S. amazonicum evaluated in the present study, determining the potential of the population to be used as an orchard for seed collection and production of seedlings with confirmed genetic variability.

Genetic diversity of Plathymenia reticulata Benth. in fragments of Atlantic Forest in southeastern Brazil.

Studies of genetic diversity in natural populations are important for the definition of conservation strategies, especially in populations reduced by processes of fragmentation and continuous forest extraction. Molecular markers stand out as interesting tools for these studies. The objective of this research was to characterize the diversity and genetic structure of Plathymenia reticulata (Fabaceae), occurring in two fragments of the Montana Semideciduous Forest in the southern of Espírito Santo State, Brazil, using inter-simple sequence repeat (ISSR) molecular markers. DNA samples from 149 individuals were analyzed using 10 ISSR primers, generating 156 fragments, of which 101 were polymorphic (64.74%). The individuals sampled were classified into three units: adult trees (A), a mixture of progenies (B), and young regenerating individuals (C). The number of loci used (N = 101) was greater than that established as optimal number (N = 88), indicating precision in analyses. The genetic diversity index of Nei (H' = 0.407) and the Shannon index (I = 0.594) were found to have high genetic diversity. Besides, through the diversity parameters evaluated, it was possible to confirm that in the areas of natural regeneration and progeny mix there is genetic diversity equivalent to that found in adults. The analysis of molecular variance indicated that most of the genetic variation is found within the groups (96.53%). Genetic differentiation among adult trees was low (ΦST = 0.03) indicating that high gene flow rates (Nm = 12.70) are counteracting the effects of genetic drift. The data obtained allowed to evaluate the potential of adult trees as matrices for seed collection and to obtain seedlings with confirmed genetic variability.