MOLECULAR CHARACTERIZATION OF ELITE LINES OF PAPAYA (Carica papaya L.) VIA SSR MARKERS
Keywords:
Carica papaya L., germplasm bank, SSR markersAbstract
This study aimed to analyze the genetic variability and to estimate diversity parameters of 23 elite papaya lines based on microsatellite molecular markers. The plant material was composed of elite lines, 18 from the 'Formosa' and five from the 'Solo' group. The expected heterozygosity (HE), observed heterozygosity (HO), and the coefficient of inbreeding (ƒ) for each genotype were estimated. The weighted index obtained the dissimilarity matrix, and the estimated genetic distance was presented graphically through the cluster analysis by the Ward method, as well as by the principal coordinates analysis (PCoA). The genotypes were also analyzed for genetic structure, using the Bayesian clustering method. Genetic variability was observed among the analyzed genotypes, mainly among the lines from the Formosa group. As for HO, four elite lines from the ‘Solo’ group had values equal to zero. However, the elite lines from the ‘Formosa’ group showed higher segregation in the loci with values ranging from 0.05 to 0.14. About ƒ, from the five lines in the 'Solo' group, four exhibited maximum fixation indexes for the analyzed loci, with the variation observed from 0.90 to 1.0, while the lines from the 'Formosa' group had a variation from 0.61 to 1.00. These results indicate the need for greater care in the process of obtaining inbreeding seeds to avoid pollen contamination, as well as the need to advance generations of self-fertilization with the lines from the 'Formosa' group to increase the level of inbreeding and ensure greater stability to hybrids that are developed from them
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