Genetic variation among sweet, purple, and yellow passion fruit accessions was assessed using inter-simple sequence repeat (ISSR) markers. Eighteen ISSR primers were used to evaluate 45 accessions. The number of polymorphic bands per primer varied from 4 to 22, with 12.4 bands per primer on average. Nei's genetic distance between accessions ranged from 0.04 to 0.35. Clustering using the neighbor-joining method resulted in the formation of 11 major clusters. It was not possible to classify the accessions according to their geographic origin, showing that there is no structure in the gene bank. The overall mean Shannon-Weaver diversity index was 0.32, indicating good resolution of genetic diversity in passion fruit germplasm using ISSR markers. Our results indicate that ISSR can be useful for genetic diversity studies, to provide practical information for parental selection and to assist breeding and conservation strategies.

Conventional methods for the selection of papaya pure lines are time-consuming. Procedures involving the use of molecular markers and the indirect selection of homozygous plants can reduce this time considerably. The objective of this study was to evaluate the informativeness of a microsatellite marker set when used in marker-assisted selection (MAS) for the development of new papaya lines. Eighty-three lines originating from two segregating F 3 populations and from papaya germplasm were used for the molecular analysis of 27 microsatellite primers. Twenty polymorphic microsatellite primers were identified, allowing the identification of 86 alleles, with an average of 3.18 alleles per primer. The observed heterozygosity values were low for both the markers (0.00-0.29) and the individual lines (0.00-0.35). The inbreeding coefficient (f) ranged from 0.634 to 1.00. Eleven lines with f = 1.00 and 18 lines with f varying from 0.953 to 0.961 were identified. In addition, papaya lines showed high genetic diversity, which will certainly contribute to the development of new varieties. Our results show that the use of microsatellites in MAS is a quick and effective procedure for the development of papaya lines.

ABSTRACT

-Due to the low genetic variability reported in the commercial plantations of papaya (Carica papaya L.), the objective of this study was analyze the genetic diversity of 32 genotypes including cultivars, landraces, inbred lines, and improved germplasm using the AFLP technique (Amplified Fragment Length Polymorphism). The genetic distance matrix was obtained using the Nei and Li genetic distance and clustering was performed using the unweighted pair-method with arithmetic mean (UPGMA). Using 11 combinations of EcoRI/MseI primers, 383 polymorphic bands were obtained. On average, 34.8 polymorphic bands were obtained per primer combination. Five clusters were formed. The traditional cultivar 'Sunrise' and the inbred line CMF-L30-08 were the closest genotypes, and the improved germplasm (CMF041) and landrace (CMF233) the most distant. The main papaya cultivars commercially grown in Brazil, as well as four inbred lines and three improved germplasm, were clustered together, however, were not grouped in the same branch. The genetic distance between the Sunrise and Golden cultivars was 0.329, and even arising from mutation and selection within the Sunrise variety, the Golden stores considerable genetic variability. Additional variability was observed in the inbred lines derived from papaya breeding program at Embrapa Cassava and Fruits. Index terms: papaya breeding, genetic resources, genetic diversity, Carica papaya L.. CARACTERIZAÇÃO MOLECULAR DE GENÓTIPOS DE MAMOEIRO COM USO DE MARCADORES DO TIPO AFLPRESUMO -Em virtude da baixa variabilidade genética relatada nos plantios comerciais de mamoeiro (Carica papaya L.), o objetivo deste trabalho foi analisar a divergência genética de 32 genótipos incluindo cultivares, variedades locais, linhagens e germoplasma melhorado, utilizando a técnica de AFLP (Amplified Fragment Length Polymorphism). A matriz de distâncias genéticas foi obtida com a distância de Nei e Li, e o agrupamento foi realizado utilizando o método UPGMA (unweighted pair-method with arithmetic mean). Utilizaram-se 11 combinações de iniciadores com corte das enzimas EcoRI / MseI. Foram geradas 383 bandas polimórficas, com média de 34,8 por combinação de iniciadores. O agrupamento dos dados permitiu a formação de cinco grupos, sendo a cultivar Sunrise e a linhagem CMF-L30-08 os genótipos mais relacionados, e CMF041 (germoplasma melhorado) e CMF233 (variedade local), os mais dissimilares. As cultivares de mamoeiro mais cultivadas no Brasil, bem como quatro linhagens e três acessos de germoplasma melhorado foram agrupadas, porém não no mesmo ramo. Mesmo sendo oriunda de mutação e seleção dentro de Sunrise, a cultivar Golden ainda possui considerável variabilidade genética, uma vez que a distância genética entre estas cultivares foi de 0,329. Variabilidade adicional foi observada nas linhagens do programa de melhoramento. Termos para indexação: melhoramento, recursos genéticos, diversidade genética, Carica papaya L..Rev. Bras.