Cytogenetic, molecular and morphological characterization of Passiflora capsularis L. and Passiflora rubra L.

Abstract

Passiflora capsularis and P. rubra are small plants with white flowers that open in the morning, favorable for indoor decoration. These species are very similar in terms of morphology, and the only differences refer to fruit color and hairiness of the ovary. Cytogenetic, molecular (SSR) and morphological studies were performed to differentiate the two species. The results of the cytogenetic analyses showed that the karyotypes of both species are similar, with 2n = 12, and 8 metacentric and 4 submetacentric chromosomes. A satellite was observed for both species, on the long arm of the second chromosome pair. Nuclear DNA content was estimated by flow cytometry of nuclei stained with propidium iodide. The 2C DNA content was 0.57 pg for P. capsularis and 0.62 pg for P. rubra; there were no significant differences between the species. Even with a high degree of cophenetic correlation (0.96), the result of cluster analysis according to Mahalanobis distance by UPGMA and Ward method using morphological and pollen descriptors has not showed a clear separation between the genotypes of P. capsularis and P. rubra. The primers tested using microsatellite markers did not present polymorphism. Cytogenetic, morphological and palynological data showed that, although P. capsularis and P. rubra have different phenotypic characteristics in relation to fruit and hairiness of the ovary, both may belong to the same species. Although the studied species were collected at the same coordinates and altitudes, the differences between them allowed their categorization as varieties of the species, indicating two botanical forms.