Analysis of transferability of microsatellite primers (SSR) in wild Passiflora species and intraspecific genetic diversity in Passiflora alata.

The genus Passiflora L. is the most representative of Passifloraceae, with over 500 known species, among which 150-200 originated from Brazil. In addition to the great commercial importance of this genus for the fruit market, many of the species have exotic flowers with a huge diversity of colors and can thereby be exploited as ornamental plants. This study was aimed at investigating the transferability of microsatellite primers in wild Passiflora species (P. cacao, P. cincinnata, P. glandulosa, P. gibertii, and P. mucronata) and characterizing 29 P. alata accessions using microsatellite primers that were previously developed in a library enriched with microsatellites from P. edulis f. flavicarpa for P. alata. The interspecies cross-amplification rate varied, and P. cacao exhibited the highest rate of amplification, suggesting a greater degree of proximity to P. edulis. The study of intraspecific accessions in P. alata found genetic similarity, with values ranging from 0.47 to 1.00 and an average similarity of 0.74. Hence, this study revealed the intraspecific genetic variability of P. alata in the Universidade Estadual de Santa Cruz's Active Germplasm Bank and will lead to the adoption of mating strategies between accessions; thus making their use more suitable for breeding purposes.

Genetic variation in a wild population of the 'sleep' passion fruit (Passiflora setacea) based on molecular markers.

Little is known about the molecular genetic diversity of most Passiflora species. We used RAPD markers to evaluate the genetic diversity of 24 genotypes of the 'sleep' passion fruit (Passiflora setacea). Twelve primers generated 95 markers, 88% of which were polymorphic. The genetic distance estimated by the complement of the Dice index ranged from 0.29 (among accessions Ps-G1 and Ps-G13) to 0.69 (among accessions Ps-G21 and Ps-G23). Genotype grouping based on the UPGMA algorithm showed considerable variability among genotypes. We conclude that P. setacea has a broad genetic base that could be exploited in breeding programs.

Confirmation of cross-fertilization using molecular markers in ornamental passion flower hybrids.

Several interspecific Passiflora hybrids are produced in the northern hemisphere for the ornamental plant market. In Brazil, production of passion flower hybrids is limited to the introgression of genes into the main cultivated species, yellow passion fruit, to be used as rootstocks. Confirmation of hybridization in the initial developmental stage is important for breeding perennial and sub-perennial plants, such as passion flowers, reducing time and costs in plant stock maintenance. In order to obtain F1 hybrids with ornamental potential, four species of Passiflora (P. alata, P. gardneri, P. gibertii, and P. watsoniana) from the Active Germplasm Bank at UESC were hybridized. Flower buds, in pre-anthesis, of the genitors were previously protected, and the female buds were emasculated. To confirm hybridization, the genomic DNA of the genitor species and the supposed hybrids was extracted and RAPD primers were used to obtain molecular markers and select passion flower interspecific hybrids. Eight primers were used to confirm hybrids derived from P. gardneri with P. alata, P. watsoniana with P. alata, P. watsoniana with P. gardneri, and P. gardneri with P. gibertii; 75, 50, 45, and 46% of the informative bands, respectively, confirmed the hybrid nature of these plants. The RAPD technique was effective in the early identification of hybrids; this will be useful for development of hybrid Passiflora progeny.

Genetic variability in wild genotypes of Passiflora cincinnata based on RAPD markers.

The genetic diversity and characteristics of commercial interest of Passiflora species make it useful to characterize wild germplasm, because of their potential use for fruit, ornamental and medicinal purposes. We evaluated genetic diversity, using RAPD markers, of 32 genotypes of Passiflora cincinnata collected from the wild in the region of Vitória da Conquista, Bahia, Brazil. Thirteen primers generated 95 polymorphic markers and only one monomorphic marker. The mean genetic distance between the genotypes estimated by the complement of the Dice index was 0.51 (ranging from 0.20-0.85), and genotype grouping based on the UPGMA algorithm showed wide variability among the genotypes. This type of information contributes to identification and conservation of the biodiversity of this species and for the identification of pairs of divergent individuals for maximum exploitation of existing variability.

Genetic diversity in wild species of passion fruit (Passiflora trintae) based on molecular markers.

In spite of the importance of and the considerable variability observed in Passiflora (Passifloraceae), little is known about the genetic diversity of most of the species of this genus. We evaluated the genetic diversity by RAPD markers in 18 genotypes of Passiflora trintae. The 15 primers generated 112 markers, 84% of which were polymorphic. The genetic distance estimated by the complement of the Dice index (average dissimilarity = 0.30) and genotype grouping based on the UPGMA algorithm showed low variability among genotypes. More attention should be given to the study and conservation of the biodiversity of this economically important genus.

Comparison of coefficients and distance measurements in passion fruit plants based on molecular markers and physicochemical descriptors.

We investigated seven distance measures and 14 similarity coefficients in a set of observations of variables of the 'yellow' passion fruit plant (Passiflora edulis Sims), submitted to multivariate analyses (distance, projection and grouping). Fourteen genotypes were characterized, based on DNA amplification with 16 random amplified polymorphic DNA primers and the assessment of nine fruit physical-chemical descriptors. The distance measurements and the similarity coefficients were compared by the Spearman correlation test, projection in two-dimensional space and grouping efficiency, using five grouping methods; the genotype ranking varied with the different techniques. Coler-Rodger distance measures, Euclidean distance square measures and Yule similarity coefficients proved to be inadequate for projection in two-dimensional space or for grouping matrices. Regardless of the origin of the distance matrix, the unweighted pair group method with arithmetic mean grouping method proved to be the most adequate. The various distance measurements, similarity coefficients and grouping methods gave different values of distortion, cophenetic correlation and stress; they influence the characterization of genetic variability and this should be taken into account for studies of yellow passion fruit plants.