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

February 2000 , Volume 13 , Number  2
Pages  210 - 216

Susumu Hiraga , 1 , 4 Hiroyuki Ito , 1 Hiromoto Yamakawa , 2 , 4 Norihiro Ohtsubo , 4 Shigemi Seo , 4 Ichiro Mitsuhara , 3 , 4 Hirokazu Matsui , 1 Mamoru Honma , 1 and Yuko Ohashi 3 , 4

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

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Accepted 18 October 1999.

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.

© 2000 The American Phytopathological Society