In Tobacco mosaic virus (TMV)-infected tobacco plants carrying the N resistance gene, a hypersensitive reaction or response (HR) occurs to enclose the virus in the infected tissue.Although a contribution of peroxidases to the fp9550bk resistance has been proposed, no evidence has been presented that tobacco peroxidase genes respond to HR.Here, we describe the HR-induced expression of a tobacco peroxidase gene (tpoxC1) whose induction kinetics were slightly different from those of acidic and basic tobacco pathogenesis-related (PR) protein genes.Interestingly, tpoxC1 was insensitive to the inducers of PR genes such as salicylic acid, methyl jasmonate, and ethephon.Spermine activated tpoxC1 gene expression at a low level and both acidic and basic PR gene expression at a considerably higher level.
These results indicate that the induced expression of tpoxC1 is regulated differently from that of classical tobacco PR genes in the N gene-mediated self-defense system click here in tobacco plants.