ISSR markers in wild species of Passiflora L. (Passifloraceae) as a tool for taxon selection in ornamental breeding.

ABSTRACT

Inter simple sequence repeat (ISSR) molecular markers were developed and used to investigate interspecific genetic variation in 25 wild species of Passiflora preserved in an active germplasm bank (BAG-Passifloras); intraspecific diversity was also analyzed in P. cincinnata accessions. Of 31 primers tested, 20 identified polymorphic loci with a total of 331 bands, suggesting high polymorphism in the sample. Interspecific polymorphism was greater than intraspecific polymorphism. This is a common finding in studies of genetic variation using dominant markers. The ISSRs revealed species-specific amplification bands in 11 species; these bands ranged from 200 to 1000 bp, and they will be of use for developing SCAR markers for the identification of germplasm in further studies. The use of Jaccard's similarity coefficient to obtain a dendrogram by the UPGMA clustering method distributed the taxa into five major groups, with differences among grouping with respect to principal coordinate analysis. Despite the high cophenetic correlation coefficient (r = 0.94) of the dendrogram, taxonomic inconsistencies were observed; similar irregularities have been reported previously in studies using dominant markers. Intraspecific analysis of P. cincinnata accessions revealed a larger genetic distance between those from Bahia (P2) and from Minas Gerais (P2), indicating that both accessions have considerable potential as parents in a genetic improvement program for this species.