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Gènes naturels de résistance aux virus chez les plantes : relations entre structure et fonction Volume 7, issue 3, Juillet 2003

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Authors
Unité de génétique et d‘amélioration des fruits et légumes, INRA, Centre d‘Avignon, dom. Saint‐Maurice, BP94, 84143 Montfavet Cedex. E‐mail : carole.carantaavignon.inra.fr

Resistance genes provide a highly efficient barrier against pathogens, including plant viruses. This review focuses on recent data about the molecular characterisation of virus resistance genes available within the natural diversity of host plants. Up to now, ten resistance genes have been cloned. Five of them ( N, Rx, Rx2, Sw‐5 and HRT) belong to the nucleotide binding site, leucine‐rich repeat (NBS‐LRR) family of resistance genes like most of the cloned genes involved in resistance to other plant pathogens. They are dominant genes that trigger hypersensitive or extreme resistance and act according to the elicitor‐receptor model. Up to now, no other cellular function has been assigned to these resistance genes. Three other genes recently characterised ( pvr2, pot‐1 and mo1) are recessive and involved in resistance to potyviruses. The resistance is associated with punctual mutations in the eukaryotic translation initiation factor 4E and the dominant susceptibility allele encodes a factor required for the virus life cycle. Finally, identification of the proteins encoded by the resistance genes RTM1 and RTM2 controlling resistance to TEV long‐distance movement in Arabidopsis thaliana, do not allow to determine whether they are involved in an active defence mechanisms against viruses or if they are required for virus long‐distance movement in the host plant.