Distribution of powdery mildew resistance genes in the Kazakhstan apple cultivar collection.

Abstract

The monogenic resistance to powdery mildew (caused by Podosphaera leucotricha) of apple trees is crucial when selecting them. DNA markers allow it to differentiate apple cultivars by individual resistance traits and determine prospective genotypes with high reliability. The presented research determines the results of molecular genetics and phytopathological analyses of apple cultivars on loci Pl-2, Pl-1, Pl-w, and Pl-d for reactions to powdery mildew. The molecular screening procedure involved using seven gene-specific markers (EM M01, EM M02, AT20-450, OPN18 SCAR, OPU02 SCAR, dr70F/dr339, and dr55F/dr336R). The resistance genes Pl-1, Pl-2, Pl-w, and Pl-d were amplified in 30 of the 34 research cultivars, with 8 Kazakh and 26 other country apple cultivars among the ones researched, according to the results of a molecular screening. Although resistance genes are still helpful for breeding, they are only recommended for use in extended pyramids of multiple resistant genes. Several cultivars are excellent candidates for additional breeding programs against powdery mildew and for pyramiding the Podosphaera leucotricha resistant genes in new cultivars.