Acta Hortic. 1127. ISHS 2016. DOI 10.17660/ActaHortic.2016.1127.62 XXIX IHC - Proc. Int. Sym. on Plant Breeding in Horticulture Eds.: N. Onus and A. Currie 401 Dissimilarity based on morphological characterization and evaluation of pollen viability and in vitro germination in Passiflora hybrids and backcrosses O.N. Jesus 1 , T.L. Soares 1 , E.J. Oliveira 1 , T.C.P. Santos 1 , D.H. Farias 2 , C.H. Bruckner 2 and Q.S. Novaes 3 1 Embrapa Cassava & Fruits, Cruz das Almas (BA), Brazil; 2 Federal University of Viçosa, Viçosa (MG), Brazil; 3 State University of Southwest Bahia, Conquista-BA, Brazil. Abstract Brazil is considered the main center of the genetic diversity and greatest worldwide producer of passion fruit. Passionfruit woodiness virus (Cowpea aphid born mosaic virus) is an important pathogenic agent of the passion fruit crop, causing severe losses in yield. Wild species of Passiflora are valuable sources of genetic resistance to this disease. Interspecific crosses are a promising method to incorporate resistance genes in commercial species (Passiflora edulis Sims.), despite problems with male sterility in developed hybrids. The objective of the present work was to study the dissimilarity based on morphological characteristics, and the viability and in vitro germination of pollen grains of progenitors, F 1 hybrids, as well as progenies of the first generation of backcross BC 1 [(P. edulis × P. cincinnata) × P. edulis]. Analysis of the severity of the viral disease showed that most genotypes were considered as susceptible to highly susceptible. The resistant hybrids did not show symptoms of foliar deformation. Cluster analysis showed two major groups; one represented by P. cincinnata and the second group by the hybrids and recurrent progenitor P. edulis. Morphological characterization of the hybrids showed phenotypic variation as to the color and shape of flowers, although the descriptors used were not able to show these differences. As expected, the progenitors (P. edulis and P. cincinnata) presented higher percentages of pollen viability, followed by the BC 1-H45 progenies. The progenies of the BC 1 will also be evaluated in the future with molecular markers aiming to accelerate the selection of hybrids with higher percentages of the genome of the recurrent parent. Keywords: Passiflora, characterization, virus, interspecific hybrids, breeding INTRODUCTION Passiflora is the most species-rich genus of the family Passifloraceae (Ulmer and MacDougal, 2004). Of 530 species, at least 140 are native to Brazil (Cervi, 2006). The species Passiflora edulis Sims. f. flavicarpa Deg. (including both the yellow and purple passion fruits) stands out among the cultivated species of Passiflora. About 95% of the passion fruit orchards in Brazil are planted with P. edulis (Borges et al., 2005). Brazil is considered the main producer of passion fruit (776 000 t), but the average productivity of 14.78 t ha -1 is considered too low compared with the potential of more than 48 t ha -1 (Freitas et al., 2011). The lack of high-yielding and pest-resistant cultivars is considered an important factor that limits the potentially high productivity. The fruit woodiness virus (Cowpea aphid born mosaic virus; CABMV) severely hampers production and reduces orchard life (Van Regenmortel et al., 2000; Nascimento et al., 2004.). P. edulis cultivars are highly susceptible to CABMV, which has led to reduced planted areas in most locations in Brazil (Oliveira et al., 2013). The passion fruit breeding program at Embrapa aims to incorporate resistance to various diseases of wild species into commercial cultivars by means of interspecific hybridization. Passiflora cincinnata Mast. is an important source of genes for genetic resistance to foliar diseases (Oliveira et al., 2013), longevity, extended flowering period and