Defence responses in Rpv3-dependent resistance to grapevine downy mildew.

The Rpv3 locus determines the ability to operate an isolate-specific hypersensitive response (HR) against Plasmopara viticola in grapevines that carry a resistant Rpv3 (+) haplotype. Artificial infection was performed on leaf discs of Rpv3 (+) and Rpv3 (-) grapevines with two distinct isolates of the pathogen (avrRpv3 (+) and avrRpv3 (-)). The plant response, including the establishment of HR and changes in expression of 33 genes, was compared to the development of the pathogen.