Mode of Action of Pentachlorobenzyl Alcohol, a Rice Blast Control Agent:Inhibition of Hyphal Penetration of Piricularia oryzae through Artificial Membrane

概要

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Pentachlorobenzyl alcohol (PCBA), a specific rice blast control agent is known to have scarce antifungal activity but prevents the hyphal penetration of blast fungus into host tissue. The present work is aimed to clarify, by using a model "fungus-artificial membrane" system, whether the inhibition of hyphal penetration is due to the direct action of PCBA to the fungus itself or the compound is metabolized within the host tissue to some fungitoxicants. Blast fungus can penetrate through cellophane membrane when a drop of conidia suspension is placed on a cellophane sheet which is floated on a boiling water extract of rice straw and incubated for 48hr at 27°C. PCBA prevents the penetration through cellophane by blast fungus at low concentration, so one of the most important mode of actions of PCBA might be the deprivation of pathogenecity of blast fungus and the possibility of biotransformation to some toxic compounds in rice leaves which actually blocks the penetration of hyphae is most likely ruled out. PCBA has no effect on boring of cellophane membrane by Cochliobolus miyabeanus and Alternaria citri which are uncontrollable pathogens by the compound. PCBA inhibits neither production nor activity of cellulase of blast fungus, therefore these results may suggest that the mechanism of hyphal penetration is rather mechanical than enzymatical.
日本植物病理学会の論文