Evaluation of Fire Blight Resistance of Eleven Apple Rootstocks Grown in Kazakhstani Fields

Abstract

Clonal rootstocks of apple trees are one of the main components of intensive horticulture, and they play an important role in regulating tree growth, yield, fruit quality, and resistance to biotic and abiotic stresses. In the two-year monitoring survey reported here, eleven rootstocks mainly used for cultivar grafting in Kazakhstan were assessed for fire blight resistance, taking genetic background into consideration. The loci FB_F7 on LG7 and FB_MR5 and RLP1 on LG3 were analyzed on the basis of SCAR and SNP markers. The rootstocks ‘Geneva 41’, ‘62-396’, and ‘Geneva16’, bearing resistant alleles for five markers (AH0JFXM, AH21B92, AH4AAGA, AH5I8MI, and AH6R6SQ), four markers (AH0JFXM, AH21B92, AH4AAGA, and AH5I8MI), and one (AH4AAGA) SNP marker, respectively, were not infected during the monitoring period despite weather conditions in 2022 being favorable for the development and spread of Erwinia amylovora. No connection was identified between the presence of a resistant allele for the AE10-375 marker and fire blight resistance responses. This is the first study to evaluate the fire blight resistance of foreign and local rootstocks grown in the Kazakhstan southern region.