Análise molecular da variabilidade genética entre genótipos de Ricinus communis L. revelada por marcadores RAPD

Abstract

The high world energy demand requires a search for renewable sources which are less harmful to environment. Castor bean (Ricinus communis L.) cultivation is an excellent alternative to compound the national energy matrix due to its traditional small and intermediate producers, standing out as a culture with high economical and social appeal, especially in Northeast region. There is a lack of information, especially at molecular level, related to the amount of high genetic variability available in this oil crop. The objective of this work was to characterize the genetic diversity within ten genotypes of Ricinus communis L. by using RAPD molecular markers. A total of seven lines and three cultivars were evaluated, which included five lines from Germplasm Bank of Embrapa Algodão, two lines from Costa Rica and three Northeastern cultivars. Genomic DNA extraction was performed according both to Graham et al. (1994) and an alternative protocol proposed in this study. Seven arbitrary oligonucleotides employed in the RAPD-PCR amplification permitted to evaluate the efficiency of the genomic DNA extraction protocols, DNA banding profiles and calculation of similarity indexes. Similarity and cluster analysis were conducted using both Jaccard and Dice coefficient and the unweighted pair group method. The similarity data matrix was converted into a dendrogram. The amplified fragments yielded a total of 58 polymorphic bands ranging from 2394 to 3386 bp. On the basis of the performed analysis, similarity indexes and data clustering revealed the occurrence of high genetic variability among the genotypes. RAPD molecular markers were efficient on the detection of DNA polymorphism within genotypes evaluated, suggesting that this marker could be suitable for further characterization studies related to the main agroindustrial features of castor bean germplasm.