ISSR and SSR markers for determining genetic relationships among three wild species of Passiflora
Passiflora cristalina, Passiflora miniata and Passiflora coccinea are wild species with similar floral characteristics, especially color and floral structure, as well as the color of their fruits. Due to their similarities, mainly the floral characteristics, these species are often confused in the field. Given that hybridization is commonplace between Passiflora species in the same region, hybrids could result from crosses involving mainly P. coccinea. We examined genetic distance and possible hybrid nature across P. cristalina, P. miniata, and P. coccinea, via ISSR and SSR markers. Genomic DNA was extracted from leaf samples of five Passiflora species (P. cristalina, P. coccinea, P. miniata, P. setacea, and P. edulis), the latter two being used as witness species. Following quantification, the amplification conditions were tested and optimized. Eighteen ISSR primers presented satisfactory amplification products, with 81 bands being amplified and 99% polymorphism. Through genetic distance and cluster analysis, P. cristalina and P. coccinea were found to be genetically close, while P. miniata remained in an isolated cluster, nevertheless with low dissimilarity with P. cristalina. Twenty-three SSR primers were tested, of which 18 were polymorphic. There was a high transferability rate, 95.65%, demonstrating that genetic proximity between tax is directly related to successful transferability. The main coordinates, genetic distance and cluster analyses showed a clear separation of species presenting similar floral characteristics (P. cristalina, P. coccinea, and P. miniata) from the remaining ones used as controls (P. edulis and P. setacea). SSR markers identified P. cristalina as a possible natural hybrid between P. miniata and P. coccinea.