Identificação de ipês (Bignoniaceae) por DNA barcoding

Abstract

Ipês are trees or shrubs of the Bignoniaceae family widely used in urban afforestation in all regions of Brazil. In winter these plants lose most of their leaves and replace them with bunches of flowers of intense colors very appreciated in landscaping. Although they are frequently used in urban vegetation and are highly popular, some species are not yet represented in the public DNA sequence banks and others are not correctly identified, even with gender indication issues. DNA barcoding is a molecular identification tool that uses small DNA sequences to identify species. To be considered a good DNA barcode, the genomic region must follow certain criteria, such as: 1) be easily amplified in the laboratory; 2) result in short sequences; and 3) be sufficiently variable to discriminate taxa at the species level. In this study, we used two of the plastid markers indicated by the Consortium for the Barcode of Life (CBOL), the matK gene and the intergenic spacer trnH-psbA, to verify their potential for identifying species of urban ipê trees in the city of Campo Grande, Mato Grosso do Sul. We study 12 species popularly known as ipê of the genera Cybistax, Handroanthus, Jacaranda, Tabebuia and Tecoma. Our results suggest that the trnH-psbA marker is the best single locus candidate to identify the ipês’ species, when compared to matK, while results based on concatenated markers (matK + trnH-psbA), indicated the same efficiency rate of identification as trnH-psbA only, but supported by higher branches. In the BLAST analyzes, we have had little success in identifying the species. This is because the public DNA sequence database does not include all species covered in this study and presents low quality sequences. This demonstrates the need for a local database for identification through DNA barcodes and for more studies that provide high quality DNA sequences, with taxonomic accuracy.