Desenvolvimento de marcadores de microssatélites e diversidade genética em acessos de Lippia alba (Mill.) N.E.Br. (Verbenaceae)

Abstract

Recent studies suggest that complete genome duplication is much more common than its stability, occurring in almost all angiosperms. Lippia alba (Mill.) N.E.Br. (Verbenaceae), is the most studied species within the genus Lippia, and it is widely used in folk medicine presenting economic importance mainly due to the richness of their essential oils. Recent studies have demonstrated the existence of at least five different ploidy levels in Lippia alba revealing a large genome plasticity making the species an interesting model of study. To better understand the genetic variation and the polyploidization process in Lippia alba, this study aimed to identify new genetic microsatellite markers and estimate the genetic diversity for 100 Lippia alba accessions. We assessed 9 loci already described and 16 new markers. The size of the fragments was detected by capillary electrophoresis using MegaBACE1000 sequencer (GE Healthcare, Buckinghamshire, UK). The identification of alleles was inferred using the Fragment Profile software (GE Healthcare, Buckinghamshire, UK). Final data were exported to an Excel spreadsheet according to the input files of each software used. PIC values (polymorphism information content) and heterozygosity were calculated using Cervus v3.0.7 software. Jaccard and Dice similarity coefficient were calculated to construct a dendrogram according to UPGMA algorithm (Unweighted Pair Group Method with Arithmetic Mean) using NTSYS and PAST softwares. Bayesian inference analysis was performed using STRUCTURE v 2.3.4 program. It was possible to observe the formation of groups according to the ploidy level and infer the possible origin of some cytotypes based on genetic similarity among accessions. Results contribute to support the hypothesis that the cytotypes have emerged by autopolyploidy.