High efficiency and reliability of inter-simple sequence repeats (ISSR) markers for evaluation of genetic diversity in Brazilian cultivated Jatropha curcas L. accessions.

Jatropha curcas L. is found in all tropical regions and has garnered lot of attention for its potential as a source of biodiesel. As J. curcas is a plant that is still in the process of being domesticated, interest in improving its agronomic traits has increased in an attempt to select more productive varieties, aiming at sustainable utilization of this plant for biodiesel production. Therefore, the study of genetic diversity in different accessions of J. curcas in Brazil constitutes a necessary first step in genetic programs designed to improve this species. In this study we have used ISSR markers to assess the genetic variability of 332 accessions from eight states in Brazil that produce J. curcas seeds for commercialization. Seven ISSR primers amplified a total of 21,253 bands, of which 19,472 bands (91%) showed polymorphism. Among the polymorphic bands 275 rare bands were identified (present in fewer than 15% of the accessions). Polymorphic information content (PIC), marker index (MI) and resolving power (RP) averaged 0.26, 17.86 and 19.87 per primer, respectively, showing the high efficiency and reliability of the markers used. ISSR markers analyses as number of polymorphic loci, genetic diversity and accession relationships through UPGMA-phenogram and MDS showed that Brazilian accessions are closely related but have a higher level of genetic diversity than accessions from other countries, and the accessions from Natal (RN) are the most diverse, having high value as a source of genetic diversity for breeding programs of J. curcas in the world.