Cláusio Antônio Ferreira de Melo

Reproductive and cytogenetic characterization in Passiflora sublanceolata

Abstract Reproductive biology (pollen-ovule ratio, pollen viability, germination in vitro pollination and stigma receptivity in vivo) and karyotype characterization by classical and molecular techniques were performed in Passiflora sublanceolata. The pollen-ovule ratio was 83.9, suggesting that this species is facultative autogamous. Pollen viability was below 70% during all anthesis period (6:00 a.m. to 12:00 p.m.). Low in vitro germination rates were observed after anthesis beginning, with none percentage at one, four and six hours and medium percentage (52.9%) at five hour. The stigma remained receptive during the whole anthesis (100%). The average fertilization percentages resulting from controlled pollinations varied between 8.4% at six hour after anthesis beginning and 50% at two and three hour. The fruit characteristics did not show significant differences by the effects of pollination time. The chromosome number was 2n = 22. The average chromosome length and the haploid chromosome length were 1.60 μm and 17.61 μm, respectively. Six CMA+3 /DAPI− terminal blocks were observed. By means of the FISH technique it was found that the species presented six 45S rDNA terminal sites, two 5S rDNA sites, terminal and pericentromeric, and telomeric hybridization sites associated only to the terminal regions. Passiflora sublanceolata has great reproductive potential and cytogenetic stability as diploid plant. The results obtained in this work will assist in the use of P. sublanceolata as genitor in interspecific hybridizations with other taxa for breeding programs primarily aimed to obtain hybrids for ornamental plant market.

Identification and characterization of karyotype in Passiflora hybrids using FISH and GISH

BackgroundA great interest exists in the production of hybrid plants of the genus Passiflora given the beauty and exotic features of its flowers which have ornamental value. Hybrid paternity confirmation is therefore important for assuring germplasm origin, and is typically carried out by molecular marker segregation. The aim of this study was to karyotypically characterize the chromosome heritance patterns of the progeny resultant from a cross of P. gardneri and P. gibertii using classical cytogenetics, chromosome banding, and molecular cytogenetics.ResultsAll analyzed genotypes showed the same diploid chromosome number as the genitor species: 2n = 18. Classical and CMA3 and DAPI staining allowed for chromosome counting and satellite identification (secondary constrictions). Fluorescence in situ hybridization (FISH) and genomic in situ hybridization (GISH) were used to characterize subgenomes by either identifying rDNA-specific genome patterns or parental genomes, respectively.ConclusionsThe heritance of chromosomal markers presenting rDNA sites from each parent for genome identification confirmed that all obtained plants were hybrids. These results will improve breeding programs involving the species of this genus. Apart from confirming hybridization, GISH allowed the visualization of recombination between the homeologous chromosome and the introgression of sequences of interest.