APPLE BREEDING FOR HIGH FRUIT QUALITY AND DURABLE DISEASE RESISTANCE

High fruit quality and durable disease resistance are crucial aspects in apple breeding directed towards sustainable production systems. The challenge of breeding durable disease resistant cultivars is approached by developing efficient molecular techniques that allow to detect the combined presence of the target resistance genes in a seedling. Examples for molecular selection towards genotypes with pyramided genetic resistance against scab (Venturia inaequalis) and powdery mildew (Podosphaera leucotricha) are promising. The genes we are currently working with include V_f, V_bj and V_r for scab resistance and P_l1 and P_l2 for mildew resistance. The correspondence of phenotypic mildew observation at two year old seedlings with molecular analysis is usually good. We have improved the efficiency in DNA extraction and to further reduce cost we are analysing up to eight markers in a single multiplex reaction. Systems have been established that allow to switch from a SCAR-based screening on agarose gels to a microsatellite based screening on a capillary-based automated fragment analyzer. Results of consumer tests carried out in Switzerland within the EU project DARE with new disease resistant apple cultivars confirm that progress has been achieved in improving fruit quality and, as a consequence, in consumer acceptance. Fruit firmness, juiciness and aroma are among the most important criteria.