VIEW ARTICLE

Physiology and Biochemistry

Interactions Between Tobacco Mosaic Virus, Pokeweed Antiviral Proteins, and Tobacco Cell Wall. K. Kumon, Aburahi Laboratories, Shionogi Research Laboratories, Shionogi & Co., Ltd., Gotanda, Koka-cho, Koka-gun, Shiga-ken, Japan 520-34; J. Sasaki, M. Sejima, Y. Takeuchi, and Y. Hayashi. Aburahi Laboratories, Shionogi Research Laboratories, Shionogi & Co., Ltd., Gotanda, Koka-cho, Koka-gun, Shiga-ken, Japan 520-34. Phytopathology 80:636-641. Accepted for publication 9 January 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-636.

Precipitation of tobacco mosaic virus (TMV) with antiviral proteins of Phytolacca americana (PAP and PAPII) and adsorption of the proteins to the cell wall of Nicotiana tabacum ?Xanthi? were studied using fluorescein isothiocyanate-labeled PAP and PAPII. The antiviral proteins conjugated with TMV in 0?60 mM KCl solution. The maximum ratio for PAP/TMV was 700:1 at pH 5 and for PAPII/TMV was 440:1 at pH 6, and these ratios were below 100:1 at pH 2 and pH 9 to 12, respectively. The antiviral proteins adsorbed to the cell wall in 0?200 mM KCl solution, but did not absorb in 300 mM KCl. However, since the formation of TMV local lesions on Nicotiana glutinosa was inhibited by the antiviral proteins in 300 mM KCl (where the conjugation between TMV and the antiviral proteins and the adsorption of the antiviral proteins on the cell are completely dissociated), the interactions are not the necessary condition for TMV inactivation. In low ionic condition, less than 60 mM KCl, the infectivity of TMV may be partially inhibited by precipitation with the antiviral proteins.