Clarifying the mechanism on systemic acquired resistance in Japanese birch plants infected with a canker-rot fungus, Inonotus obliquus

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The fungal infection specific proteins were detected and identified for the Japanese birch plantlets No.8 infected with a canker-rot fungus of birch trees, Inonotus obliquus IO-U1 strain at the early stage of their fungal infection. As a result, it was found that oxidative burst and systemic acquired resistance occur as the protective reactions in the plantlets No.8 infected with the fungus. In addition, anatomical and histochemical observations were performed for the two kinds of plantlets, No.8 and Tohoku, infected with IO-U1 strain. Consequently, it was suggested that deposition of phenolic compounds and their polymerized substance, and the formation of suberized necrophylactic periderm inhibit the growth of the fungal hyphae in the two kinds of plantlets infected with the fungus. Furthermore, isozyme analysis of the peroxidases produced in the plantlets No.8 was carried out. In consequence, it was indicated that the peroxidase isozymes of the infected plantlets are specialized for polymerization of phenolic compounds. Moreover, it was investigated by using proteome analysis whether systemic acquired resistance (SAR) occurs in the plantlets No.8 to which the SAR-inducing compound, salicylic acid was artificially administered. As a result, it was indicated that administration of salicylic acid to the plantlets No.8 induces SAR in the plantlets. In addition, it was suggested that the occurring resistance mechanisms are different between the case of the fungal infection and that of administration of salicylic acid to the plantlets.