Analysis of genetic diversity of Hyptis pectinata (L.) Poit. plants using ISSR markers.

Hyptis pectinata, popularly known as 'sambacaitá' or 'canudinho', is a medicinal and aromatic species widely used in the Brazilian Northeast. In Sergipe, the excessive extraction of natural resources may reduce the genetic variability of native plants. Thus, molecular markers have frequently been applied to the characterization of genetic diversity as the basis for germplasm conservation and breeding programs. The objective of the present study was to evaluate the genetic diversity of H. pectinata plants collected in different municipalities of the State of Sergipe using ISSR molecular markers. Thirty-four primers were tested, nine of which were selected for providing reproducible and analyzable amplification products, resulting in 67 polymorphic bands. The expected heterozygosity ranged from 0.32 to 0.45, with a mean of 0.39. Polymorphism information content was of 0.49, which classifies the markers as moderately informative. A dendrogram was constructed using unweighted pair group method with arithmetic mean, forming three clusters: Cluster I (79 plants); Cluster II (4 plants); and Cluster III (2 plants). Jaccard's similarity coefficients ranged from 0.06 to 0.98. The plants SAM-117 and SAM-119 presented greater similarity. Conversely, SAM-107 and SAM-171 were the most genetically distant. In general, H. pectinata plants collected in the State of Sergipe presented low to moderate genetic diversity.

Genetic diversity of native populations of Croton tetradenius Baill. using ISSR markers.

Brazil has about 300 Croton species in different types of vegetation. Croton tetradenius Baill., which is endemic to the Northeast region and predominant in the Caatinga vegetation, stands out among the several species of this genus. Considering the importance of knowing the genetic variability of a species, the objective of this study was to analyze the genetic diversity of the genotypes of natural populations of C. tetradenius in the State of Sergipe, using ISSR molecular markers. Forty individuals were sampled in four natural populations of the State of Sergipe, Brazil. Thirteen primers were used for DNA amplification using ISSR-PCR, totaling 77 amplified fragments, of which 94.8% were polymorphic. Results of the cluster analysis obtained by the Jaccard's similarity index, using the UPGMA method, resulted in the formation of six distinct clusters. Analysis of molecular variance (AMOVA), used to estimate the genetic variability among populations, revealed significant genetic variance (P < 0.01) between and within the studied populations, and most of the genetic diversity was found (87%) within populations. According to the Jaccard's similarity index, none of the studied plants was genetically identical. CTE210 and CTE305 presented high similarity index (0.76), while CTE105 presented low similarity index (<0.16) with all related individuals. ISSR markers were efficient and allowed the formation of a molecular profile, and had sufficient polymorphism to estimate the genetic variability between the accessions of the studied populations.