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An HR-Induced Tobacco Peroxidase Gene Is Responsive to Spermine, but Not to Salicylate, Methyl Jasmonate, and Ethephon

¹Department of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, 060-8589 Japan; ²Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572 Japan; ³Department of Molecular Genetics, National Institute of Agrobiological Resources, Tsukuba, Ibaraki, 305-8602 Japan; ⁴Core Research for Evolutional Science and Technology (CREST), Chiyoda-ku, Tokyo 101-0062, Japan

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 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 in tobacco plants.

Additional keywords: wounding.