Morphological aspects of Passiflora edulis f. flavicarpa chromosomes using acridine orange banding and rDNA-FISH tools

Passiflora edulis f. flavicarpa is considered the most important species of the genus Passiflora, mainly because of its botanical and commercial importance, as well as for crop breeding and genomic programs. However, its chromosome characterization has been conflicting on what concerns the number and localization of secondary constrictions (SC) and nucleolus organizer regions (NORs). In this context, conventional and molecular cytogenetic methodologies have been adapted to resolve these morphology problems. Cellular dissociation, air-drying techniques and Giemsa staining, acridine orange fluorochrome and fluorescent in situ hybridization (FISH) methodologies were used, We identified four secondary constrictions, in the subterminal portion of the long arm of chromosomes 1 and 8 and in the subterminal portion of short arm of chromosomes 2 and 7. Regions emitting yellowish fluorescence were observed on chromosomes 7 and 8 after acridine orange staining. The same pairs were evidenced with the rDNA 18S probe used in the FISH technique, indicating that only two of the four secondary constrictions are related with NORs.