Divergência genética de acessos de meloeiro por meio de marcadores rapd

Abstract

The melon (Cucumis melo L.) is one of the most important vegetables for the Brazilian northeast. It is a highly polymorphic species, with several variations in its characteristics, which can be exploited for genetic improvement. The objective of this work is to study the genetic diversity of acessions of C. melo L. from the Cucurbitaceae Active Germplasm Bank for the Brazilian Northeast region with the use of RAPD molecular markers. Were used 28 RAPD primers, for the molecular analysis, which create 242 (67,41%) polymorphic markers. The complement to the Jaccard index was used to generate the matrix of genetic distances from the molecular markers data. The genotypes were grouped by two methods: the UPGMA and the Tocher method. The RAPD markers enabled the identification of genetic distance for all studied accessions. The average genetic distance among the genotypes was 0,22, with minimum distance between the accessions BGMEL 66.0 e BGMEL 67.0 and maximum between BGMEL 63.0 e BGMEL 111.0. The access BGMEL 97.2 was the most distanced from the other accessions. the UPGMA and Tocher methods perfectly agreed, by utilizing 0.189 as a cut off point (77.87% dissimilarity) at the dendrogram, with formation of seven groups. The study showed the genetic variability among accessions. It was also observed strong association among the groups formed by clustering methods based on RAPD markers and the taxonomic classification of the genotypes, unlike what occurred in the case of geographical origin of accessions.