Identification of dwarfism loci Dw1 and Dw2 in clonal apple rootstocks using molecular markers

Abstract

The paper presents the results of identification of quantitative trait loci (QTL) of Dw1 and Dw2 involved in the control of dwarf growth in clonal apple rootstocks using the molecular markers. In total, 14 forms of rootstocks were analyzed. The microsatellite markers Hi01c04, Hi04a08, CH03a09 (for the Dw1 locus), MDP0000365711, and MDP0000243703 (for the Dw2 locus) were used in the study. Analysis of the results did not reveal a relationship between the presence of a marker and the manifestation of a sign. Of the three markers of the Dw1 locus, only Hi01c04 amplifies a fragment of the expected size of 120 bp. It was found in 9 forms of rootstocks (PB-4, 57-491, 83-1-15, M9, G16, 2-12-10, 2-9-102, 4-6-5 and 70-20-20). The Hi01c04 marker was identified in both dwarf and medium-sized forms. Of the two markers of the Dw2 locus, the desired fragment is amplified in MDP0000365711. It is typical for almost all genotypes. The exception is 83-1-15, 2-12-10 and 70-20-20, which have a null allele. To assess the genetic diversity of the Dw1 and Dw2 loci, 6 microsatellite sequences Hi01c04, Hi04a08, CH03a09, CH02d08, MDP0000365711, and MDP0000243703 were used. In 14 studied samples, 29 allelic variants ranging in size from 102 bp. up to 170 bp were identified. The number of alleles per locus varied from 1 (for the MDP0000365711 locus) to 7 (for the Hi04a08 locus). No rare alleles were identified. All alleles were observed more than three times. Based on the analysis of SSR spectra, a dendrogram reflecting the similarity of the genotypes under study was built.