Conservação dos recursos genéticos de Passiflora e seleção de descritores mínimos para caracterização de maracujazeiro

Abstract

The human activities have been caused severe genetic erosion in the genus Passiflora. Therefore, Embrapa Mandioca e Fruticultura has an Active Germplasm Bank of Passiflora, with about 220 accessions is maintained in vivo and seeds stored in cold chambers. The objectives of this study were to monitor possible allele losses and variation in their frequency in the germplasm regeneration cycle, so as to estimate the effective population size due to the conservation strategy adopted in four species of Passiflora. In addition, we aimed to select and define a set of minimum descriptors for the characterization of P. edulis. Microsatellite markers were used for monitoring the allelic losses on four accessions and in the estimate of effective population size, whereas morph-agronomic markers and multivariate analysis were used in the definition of minimum descriptors. We identified significant changes in the number and frequency of alleles with the selection of plants to represent the accessions being losses and fixation of alleles more frequent for smaller samples. Loses up to 49% of alleles were observed in P. cincinnata specie, which can compromise future genetic gains in breeding programs. The effective population size, inversely proportional to the observed inbreeding, influences the conservation strategy used for each species. Regarding the selection of minimum descriptors, four quantitative and two qualitative descriptors were discarded. Consequently, the list of minimum descriptors for P. edulis characterization may consist of 16 quantitative and six multicategoric descriptors, without information loss.