Résumé
Lr34 is a wheat gene which confers a durable, partial and broad spectrum resistance against the three wheat rusts and powdery mildew. Lr34 encodes for an ABC transporter protein and only one resistance-conferring Lr34 allele (Lr34res) has been found in wheat so far. Lr34res evolved as a result of two gain-of-function mutation that occured post domestication, 10000 years ago. Lr34res is only found in cultivated wheat but not in wild wheat progenitor. Consistent with the very recent emergence of Lr34res, an Lr34-like disease resistance with a similar durability and broad-spectrum specificity has not been reported in other important crop species sich as rice or barley. We therefore transformed the wheat Lr34res into rice, one of the most important cereals, and observed that the transgenic lines showed resistance against different rice blast (Magnaporthe oryzae) isolates on a macroscopic and a microscopic level. This hemi-biotrophic fungus is one of the most devastating rice diseases in the world and causes important yield losses every year. Lr34res was shown to provide resistance against biotrophic fungi in wheat but with these results we could show that the spectrum of resistance is even broader, including hemi-biotrophic fungi as well. More interestingly, it was possible to identify one transgenic line with a plant development and some yield parameters comparable to the sister line but with a resistance against rice blast. In the future, Lr34res would be a very useful tool in order to improve disease resistance in rice or other species. (Texte intégral)