Progress in apple breeding for resistance to fire blight

Abstract

The paper presents the most important issues concerning the breeding of apple trees resistant to fire blight, which creates great op­portunities to increase the efficiency of apple fruit production without the use of other protection methods, including the chemical treatment. The phenotypic assessment of susceptibility of apple genotypes to the disease is based on observations on the occurrence of symptoms in field and/or closed facilities, e.g. in the greenhouse. Molecular biology methods, including identification of resistance mark­ers, and biotechnology are valuable tools to accelerate the breeding process. Breeding programs conducted in various research centers around the world use wild species of the genus Malus and commercial cultivars of apple. Apple rootstocks with very high resistance to fire blight (USA) and a number of scab-resistant cultivars, also showing high resistance to the disease (Germany, Switzerland) have already been bred. In recent years cultivar Early Szampion and clone No. 69 (J-2003-05) have been bred in Poland. Both genotypes are characterized by a very high resistance, and produce attractive tasty fruit. They have the prospect of being used in breeding programs and commercial plantings.