Diversity studies in Passiflora subgenus Tacsonia

About 60 species of the genus Passiflora produce an edible fruit. Most of them are found in the subgenera Passiflora (maracujas and granadillas) and Tacsonia (banana passion fruits). The Andean subgenus Tacsonia is characterized by a long floral cup (about 10 cm), and a corona reduced to a single row of small tubercules. We studied the morphological and isozyme diversity among the most widespread species: the cultivated P. mollissima ('curuba de Castilla'), P. cumbalensis (the rosy passion fruit), P. mixtea, P. pinnatistipula, and 'Curuba india', an undetermined culfigen of banana passion fruit, which is taking economic importance. The study also included P. manicata, from the intermediate subgenus Manicata. Cluster analysis was applied on qualitative morphological data from 45 Ecuadorian accessions and on isozyme data from 331 accessions from Venezuela, Colombia and Ecuador. Morphologically, the accessions group themselves consistently by species, demonstrating negligible intraspecific variation. P. mollissima appears closer to P. mixta and more distant from P. cumbalensis than in the current taxonomy. It was clearly distinct from the 'curuba india'. P. pinnatistipula is logically intermediate between all these species and the more distant P. manicata. Six polymorphic enzyme systems (IDH, 6-PGDH, PGM, DIA, PRX, ACP) revealed 55 zymotypes characterized by the presence/absence of 30 electromorphs. Polymorphism was much higher in the wild than in the cultivated accessions. The analysis clustered the accessions into seven main groups, four of which correspond to particular types or species: 'curuba india', P. cumbalensis, P. pinnatistipula, and P. manicata. P. mollissima and P. mixta formed three groups, one dominated by Colombian cultivated material, the second by Colombian wild accessions, and the third by Ecuadorian accessions. As in the morphological study, P. manicata appeared distant from the other species while P. pinnatistipula occupied an intermediate position. 'Curuba india' appears to be a new taxon of cultivated banana passion fruit. The close relation between P. mollissima and P. mixta is interesting for banana passion fruit improvement. (This work is partially funded through the Colciencias project 1203-12-097-98). (Résumé d'auteur