Rice gene OsNAC19 encodes a novel NAC-domain transcription factor and responds to infection by Magnaporthe grisea

The plant-specific NAC-domain proteins have been identified to play important roles in plant responses to stresses or in plant development regulation. In this research, a full-length cDNA clone OsNAC19 (Oryza sativa NAC19), encoding a novel NAC-domain protein, was isolated from a cDNA library prepared with rice leaves infected by incompatible race 131 of blast fungus (Magnaporthe grisea). The similarity between OsNAC19 and the members of OsNAC3 subgroup is from 65.87 to 51.53%. One plant-specific NAC domain is located in the N-terminus of OsNAC19. The protein OsNAC19 was localized in the nucleus of onion epidemical cells. The fusion protein of OsNAC19 with GAL4 DNA-binding domain (BD) activated the reporter genes LacZ and HIS3 in a yeast assay system, and the activation domain was located within amino acid 181–240 of its C-terminal region. The expression of gene OsNAC19 was high in rice seedling roots, culms and blade sheathes, but its expression in rice leaves was low. The expression of OsNAC19 in rice leaves could be induced by the infection of blast fungus, and by application of exogenous methyl jasmonate (MeJA), ABA and ethylene but ethylene had a relatively weak induction effect. These data suggest that OsNAC19 protein is a transcriptional activator involved in rice response to infection by M. grisea and may play a role in the MeJA-mediated signaling pathway.