Characterization of microsatellite loci in apple (Malus × domestica Borkh.) cultivars.

Abstract

Apple fruits constitute an important part of horticultural production in Lithuania and worldwide. Tools for assessment of genetic polymorphism and genotyping are required for breeding and research on apple genetic resources. The aim of the present study was to characterize microsatellite loci of indigenous and traditional Lithuanian apple tree (Malus × domestica Borkh.) cultivars and select primer pairs suitable for genotyping of the cultivars. Thirty-seven traditional and indigenous cultivars developed during the last century, and, as a reference, a set of eleven standard cultivars available at the collection of apple genetic resources at the Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry were assessed. Apple genotyping was performed using eleven PCR primers specific to polymorphic microsatellite loci of Malus × domestica as recommended by the European Cooperative Programme of Plant Genetic Resources (ECPGR) Malus workgroup. All microsatellite loci exhibited a high level of polymorphism – 8 to 14 alleles with a mean value of 10.45 for traditional and indigenous cultivars and 5 to 12 alleles 7.55 in average for reference cultivars. The observed heterozygosity varied from 0.70 to 0.97 with an average of 0.84 for traditional and indigenous cultivars and from 0.64 to 1.00 with a mean value of 0.90 for reference cultivars. CH01g12 was the most polymorphic micorsatellite locus in the group of 37 traditional and indigenous cultivars, while CH02b10 locus exhibited the highest polymorphism in the set of reference cultivars. The polymorphism of the microsatellite markers allowed us to specifically identify 35 of the traditional and indigenous cultivars.