Association between herbivore resistance and fruit quality in apple

Abstract

Enhanced fruit quality, plant health, and productivity are major objectives in apple breeding. The undesirable fruit quality traits frequently associated with pest- and disease-resistant cultivars may be related to resource allocation tradeoffs. The objective of the present study was to evaluate the association between insect resistance and fruit quality in apple. The studied 'Fiesta' × 'Discovery' apple progeny was characterized by reasonable fruit firmness and optimal sugar content and acidity but small fruit size. There was a positive correlation between codling moth (Cydia pomonella) fruit infestation and fruit firmness. Additionally, a positive correlation was detected between shoot infestation by green apple aphid (Aphis pomi), fruit number as well as sugar content. Infestation by the apple leaf miner moth (Lyonetia clerkella), the rosy apple aphid (Dysaphis plantaginea), the leaf-curling aphid (Dysaphis cf. devecta), and the apple rust mite (Aculus schlechtendali) was not significantly related to fruit quality traits. The positive relationship of increased infestation by some pest insects and quality-determining fruit characteristics such as firmness or sugar content points to a possibly increased necessity for plant protection measures in apple cultivars producing high-quality fruits. One possible explanation of higher pest infestation in cultivars producing fruits with high quality is a tradeoff between resource allocation to defensive secondary metabolites or to fruit quality. By identifying a relationship between pest infestation and fruit quality, the present study highlights the need to consider pest resistance when breeding for highquality apple cultivars. The use of genetic markers for fruit quality and pest resistance in marker-assisted breeding may facilitate the combined consideration of fruit quality and pest resistance in apple breeding programs.