Desenvolvimento de marcadores IRAP para a genotipagem de Phaseolus vulgaris L.

Abstract

Common bean is a legume of great importance in human nutrition. Its cultivation is done mostly by small farmers, and it is an important source of income and subsistence for them. Knowing the genetic resources available is an important tool for sustainable development of agriculture. The loss of genetic resources and consequent loss of genetic variability has direct implication in the environment, food production and economy. Agriculturally, its involves loss of genetic constitutions that contribute to crop improvement. Molecular markers are the key in the study of variability and genetic diversity. They are accurate ways to identify and do a thorough evaluation of genetic variation that helps to understand the genetic diversity among varieties of the same species. The molecular DNA markers detect variations in nucleotide sequences into specific genome sites. The IRAP markers (InterRetrotranposon Amplified Polymorphism) are based on retrotransposons. These markers examine the variation in insertion sites of retrotransposons, and the amplification is made in the DNA sequence between the regions of the long terminal repeats (LTR) of two retrotransposons. The molecular characterization of common bean (Phaseolus vulgaris L.) genotypes is an important option for registration of cultivars and characterization of landraces. The design of primers was performed with RJPrimer software from in silico search of retrotransposons available in Phytozome 10.1 database (P. vulgaris Genome v1.0). The genomic DNA was obtained from young leaves of 22 common bean genotypes. DNA amplification was performed by PCR using 12 designed IRAP primers pairs. The PCR products were subjected to 2% agarose gel electrophoresis. The analysis of the dissimilarity of thegenotypes was performed with NTSYS-pc software using Dice coefficient. A dendrogram was generated from the UPGMA clustering analysis. The degree of correlation between the dissimilarity matrix was obtained by performing Mantel test with 1000 permutations. Two dendrograms of dissimilarity were generated allowing a visible separation between the landraces and commercial genotypes. The IRAP markers were able to point out the similarity between parental genotypes and their descendents as in the case of IPR Andorinha, BRS Estilo and their F2 generation. Was observed a similarity between IPR Siriri and IPR Tangara, which are related. It was possible to identify the genetic similarity between genotype Bolinha and the landrace Land2 that have very similar phenotype. The developed IRAP primers allow the identification of genetic polymorphisms in P. vulgaris and can be used as an auxiliary tool in the characterization of genotypes and identification of redundancies present in working collections.