Genetic diversity in the physic nut based on ISSR markers

The use of oleaginous species is an alternative in the growing search for biofuels, where the physic nut (Jatropha curcas) stands out due to its robustness and the quality of its oil. The result is a demand to develop cultivars of this species, and for this, a knowledge of its genetic variability is fundamental. The aim of this study was to evaluate the genetic diversity of 23 accessions of jatropha collected in different regions of Brazil. The DNA of the accessions was extracted and analysed by means of 12 ISSR primers. A genetic dissimilarity matrix was generated from the electrophoretic profiles of the bands and used in elaborating the dendrogram and in grouping the individuals, which was also carried out as per the Tocher method. A Coincidence Index was calculated to check the existence of a relationship between the groups of accessions and their places of collection. A total of 44 bands were amplified, of which 26 were polymorphic (49.08%). The genetic distance between the genotypes ranged from 0.034 to 0.314. The clustering methods resulted in the formation of distinct groups, where three groups were formed by the Tocher Method and seven by the UPGMA. The accessions under study had a narrow genetic base, which could cause difficulties for the process of crop breeding, and lead to greater genetic vulnerability in the new cultivars.