Résumé
A number of resistance genes against biotrophic pathogens recently have been cloned from wheat and barley. These include the barley stem rust resistance gene Rpg1, the leaf rust resistance genes Lr10 and Lr21 in wheat and several alleles from the highly diverse powdery mildew resistance loci Mla in barley and Pm3 in wheat. In addition, the durable and recessive mlo gene also conferring powdery mildew resistance as well as the viral resistance genes rym4 / rym5 were isolated from barley. There are many advanced projects in a number of research groups aimed at the isolation of additional resistance genes, including some quantitative trait loci with major effects on resistance against biotrophic and necrotrophic pathogens. The availability of these genes for transgenic approaches as well as the development of highly diagnostic markers to test for the presence of the gene in plants will allow new breeding strategies. Resistance breeding, possibly more than breeding for any other major trait, will benefit enormously and rapidly from this new molecular information: a rapid diagnosis of resistance genes as well as a rational combination of qualitative and quantitative resistance factors based on molecular knowledge will become feasible in the next decade.