Disease resistance protein. Resistance proteins guard the plant against pathogens that contain an appropriate avirulence protein via a direct or indirect interaction with this avirulence protein. That triggers a defense system including the hypersensitive response, which restricts the pathogen growth. H2O + NAD(+) = ADP-D-ribose + H(+) + nicotinamide Isoform 1 is more prevalent before and for 3 hours after tobacco mosaic virus (TMV) infection, while isoform 2 is more prevalent 4 to 8 hours after TMV infection. The TIR domain mediates NAD(+) hydrolase (NADase) activity. Self-association of TIR domains is required for NADase activity. Isoform 1 and isoform 2 are necessary to confer complete resistance to TMV. Belongs to the disease resistance NB-LRR family.