Molecular characterization and genetic variability among peach rootstocks based on codominant markers

Abstract

The objective of this work was to establish a standard for molecular characterization and differentiation of peach rootstocks, as well to estimate genetic variability parameters based on codominant markers. Fourteen genotypes were evaluated using primers for microsatellite loci from the BPPCT and UDP series and for the STS and SCAR loci. The electrophoretic profile was recorded for the presence or absence of bands, which were used to calculate the genetic similarity among cultivars by the simple matching coefficient, and to perform cluster analysis by the unweighted arithmetic average (UPGMA) method. The number of alleles per locus, allele frequencies, observed and expected heterozygosity, inbreeding, and polymorphic information content (PIC) were calculated. The 18 loci produced 82 polymorphisms, allowing for the elaboration of a dendrogram, which discriminated the genotypes into three main groups. Observed and expected heterozygosity in the 18 SSR loci were 0.66 and 0.22, respectively. Maximum values for inbreeding (1.0) were identified in loci UDP 98407, UDP 98412, BPPCT 034, BPPCT 016, SCAR‑SCAL 19, and STS OPAP4. PIC ranged from 0.81 for SCAR‑SCAL 19, to 0.46 for UDP 98407. The polymorphism of the 18 markers allows for an accurate genetic relationship among the evaluated peach genotypes and the identification of the more contrasting ones for use in breeding programs.