Intra-genotypic variability in elite parent lines of papaya

Abstract

This study aimed to characterize papaya lines via microsatellite markers, and select genotypes based on the fixation index in order to promote the genetic purification of important commercial hybrids parent lines. Overall, 400 genotypes from three parental lines (JS-12, SS-72/12, and Sekati) were genotyped. Expected (HE), observed (HO) heterozygosity, and fixation index (F), were estimated. Genetic distances were estimated using an unweighted index, which was graphically presented via cluster analysis using the UPGMA and PCoA. Intra-genotypic variability was detected in both JS-12 and Sekati lines, while an absence of it was observed in SS-72/12. Such variability may positively contribute to the fitting of ‘UENF/Caliman 01’ and ‘UC-10’ hybrids into the traits of commercial interest how size and weight fruit. Regarding the fixation index, 293 genotypes showed maximum values (F=1) facilitating the genotypes selection process. Concerning population analysis, a close proximity between heterotic group ‘Formosa’ lines was observed, while a greater distance among ‘Solo’ group ones, and this enables systematic exploitation of such material. The fixation index maximum enabled the 80 genotypes selection thereby contributing to the parents genetic purification, since, the selected genotypes will be used in future hybridization steps to generate hybrids fitted into the traits of commercial interest.

Key words
Carica papaya L; genetic variability; microsatellite markers; genetic purification.