ABSTRACT. The limited number of papaya varieties available reflects the narrow genetic base of this species. The use of backcrossing as a breeding strategy can promote increases in variability, besides allowing targeted improvements. Procedures that combine the use of molecular markers and backcrossing permit a reduction of the time required for introgression of genes of interest and appropriate recovery of the recurrent genome. We used microsatellite markers to characterize the effect of firstgeneration backcrosses of three papaya progeny, by monitoring the level of homozygosity and the parental genomic ratio. The homozygosity level in the population ranged from 74 to 94%, with a mean of 85% for the three progenies (52-08, 52-29 and 52-34). The high level of inbreeding found among these genotypes increases the expectation of finding more than 95% fixed loci in the next generation of self-fertilization of superior genotypes. The mean proportion of the recurrent parent genome found in first-generation backcross progeny was 50.1%; 52-34 had a larger genomic region in common with the recurrent genitor and the lowest level of homozygosity. The progeny 52-08 was genetically closest to the donor genitor, and it also had the highest level of homozygosity. We found that linking conventional procedures and molecular markers contributed to an increase in the efficiency of the breeding program.

ABSTRACT. Brazil is the world leader in papaya production. However, only a small number of cultivars are registered for commercial planting, mainly owing to delays in obtaining cultivars and the high costs of the field phase of breeding programs. These costs can be reduced when molecular tools are combined with conventional breeding methods. In the present study, we conducted a molecular analysis of a self-fertilized population of a first backcrossing generation of BC 1 S 1 papaya plants via microsatellite markers both to monitor the level of homozygosity and the gene/allele transfer that confers the Golden trait (fruit color) and to assess the parental genomic proportion in the genotypes studied. Based on the analysis of 20 polymorphic microsatellite loci, 19 genotypes with the Golden trait belonging to BC 1 S 1 were evaluated in addition to the parental genotypes. Genetic distance was estimated through weighted index. The genotypes were then grouped using the hierarchical nearest neighbor method, and the analysis of principal coordinates was used to measure the proportion of parental genomes in the segregating genotypes. The mean value of the inbreeding coefficient was 0.36. The analysis of the principal coordinates revealed that on average, 64% of the recurrent parent genome was present in the population. Together, the analyses allowed the selection of 3 individuals for the next backcross cycle (33BC 1 S 1 -18, 34BC 1 S 1 -16, and 37BC 1 S 1 -10). These individuals had a higher proportion of the recurrent parent and were grouped close to the recurrent parent in the cluster analysis.

Abstract-STATs (signal transducer and activator of transcription) are a group of transcription factors that mediate actions of a variety of peptide hormones and cytokines within target cells (for example prolactin and growth hormone). In particular, STAT5A gene is a candidate marker for quantitative traits in farm animals. In this study, the STAT5A/Eco81I polymorphism was investigated with PCR-RFLP in a sample of Garganica goats. Garganica breed is an Italian goat breed that originates in the Gargano promontory, in Apulia region, by crossing the autochthonous population of goat with west European goats. Garganica breed show an exceptional ability to adapt to particularly difficult environments, as well as an extraordinary capacity to utilize poor pasture that would not otherwise be used. The investigated polymorphism is a substitution C→T at position 6852 within the exon 7 of the STAT5A gene. Only two out of three possible genotypes were identified in the population. The allelic frequencies of alleles C and T were 0.863 and 0.137 respectively and the population was kept in Hardy-Weinberg equilibrium. Moreover, some population genetic indices were also reported.