Bifunctional nuclease with both RNase and DNase activities. Involved in basal defense response. Participates in abscisic acid-derived callose deposition following infection by a necrotrophic pathogen. Up-regulated by pathogens, abscisic acid, etephon, salicylic acid and methyl jasmonate. Increased susceptibility to fungal pathogens. Belongs to the bifunctional nuclease family.