Breeding apples with durable disease resistance

Apple cultivars with high fruit quality, good productivity and durable disease and pest resistance are highly required in ecological Fruit growing. In the past apple breeders mainly used single resistance genes giving good field resistance towards scab and mildew. They originate from wild species such as Malus floribunda 821, M. zumi and M. robusta. However, this type of resistance can be overcome by new pathogen races. Today the main emphasis is on the combination of functional different major resistance genes and the use of quantitative resistance to achieve durability. Molecular markers were developed which particularly permit the detection of major resistance genes. The combined presence of the target resistance genes in a seedling can be determined by marker-assisted selection (MAS). Currently similar markers for loci on the genome which determine quantitative resistance (QTL) are being developed. Benefits and limits of durable disease resistant variety in organic Fruit growing will be discussed