Disease resistance (R) protein that confers resistance to multiple powdery and downy mildew by promoting cell death (PubMed:24033846, PubMed:28008335). Acts as a NAD(+) hydrolase (NADase): in response to activation, catalyzes cleavage of NAD(+) into ADP-D-ribose (ADPR) and nicotinamide; NAD(+) cleavage triggering a defense system that promotes cell death (PubMed:31439792). H2O + NAD(+) = ADP-D-ribose + H(+) + nicotinamide Homodimer; homodimerization is required for NAD(+) hydrolase (NADase) activity. The TIR domain mediates NAD(+) hydrolase (NADase) activity. Self-association of TIR domains is required for NADase activity. Belongs to the disease resistance TIR-NB-LRR family.