Fire blight resistance breeding

Fire blight, caused by the Gram-negative bacterium Erwinia amylovora, is a disastrous disease to pome fruit. Although fire blight is now a regulated non-quarantine pest (RNQP) in the European Union, for a long period it was regarded as a quarantine disease in Europe. Highly effective control is only possible with the application of antibiotics, but most European countries have banned their use. A sustainable approach would be the growing of fire blight resistant cultivars. Since most apple cultivars grown worldwide are susceptible to the disease, breeding of new apple cultivars resistant to fire blight would be an ecological and sustainable approach to overcome the menace of the disease. Major fire blight resistance QTLs have been mainly detected in wild Malus species, but the conventional introduction of these QTLs into cultivated apple takes decades. Methods using biotechnological approaches can reduce the time needed for the development of fire blight resistant cultivars. We will highlight the possibilities and difficulties in breeding for resistance to fire blight in apple (Malus).