Caracterização citogenetica de algumas especies e hibridos interespecificos de Passiflora

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

ln passion ffuit breeding programs interspecific hybridization has been the best altemative in searching for diseases resistance in the Passiflora edulis f flavicarpa, the most cultivated commercial species. Studies were carried out on chromosomic characterization and meiotic behavior. The present work aimed to contribute with basic cytogenetic informations to breeding programs in three species of passion ffuit, P. edulis f flavicarpa, P. setacea and P. incarnata and in two interspecific hybrids: P. edulis f flavicarpa X P. setacea ( sexual hybrid) and P. edulisf flavicarpa + P. incarnata (somatic hybrid). The karyotypes of the parental species and the sexual hybrid showed 2n = 18 chromosomes. The somatic hybrid present 2n = 36, confirming the protoplast fusion. The species karyotypes showed similar morphology, with metacentric and submetacentric chromosomes. The last ones always presenting secondary constriction . AlI the studied species and hybrids showed a larger chromosome, number 4 pair, with a secondary constriction in the end of the long armo The P. setacea species and the hybrid P. edulis f flavicarpa X P. setacea showed secondary constrictions in three pairs of chromosomes while the somatic hybrid had them in four pairs. P. incarnata was the species with the largest average absolute length and the sexual hybrid had the largest karyotype total length when compared with the other species analyzed. The somatic hybrid had twice the karyotype totallength when compared with the other species and with the sexual hybrid. The meiotic analysis in both hybrids showed irregularities during the microsporogenesis. A greater homology represented by the number of bivalents, was observed in the hybrid between P. edulis f flavicarpa and P. setacea. The presence ofmultivalents in the sexual and the somatic hybrids gives evidence of genetic recombination. Micronuc1ei of the somatic hybrid in the meiosis II was observed as a consequence, the number of microspores in tetrads phase was higher than four and pollen grains with varied sizes were observed. The pollen viability was low in both hybrids, probably due to the meiotic irregularities.

ASSUNTO(S)

maracuja citogenetica

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