Mechanism of Selective Toxicity of Fungicide

Metabolism of Pentachloronitrobenzene by Phytopathogenic Fungi

Abstract

Metabolism of pentachloronitrobenzene (PCNB) by phytopathogenic fungi was studied with reference to selective toxicity. PCNB is metabolized to two substances, pentachloroaniline (PCA) and pentachlorothioanisole (PCTA), by Fusarium oxysporum f. lycopersici. Antifungal activities of PCA and PCTA against phytopathogenic fungi are extremely inferior to that of parent compound, PCNB, which indicate that these two biotransformation reactions belong to detoxication. Metabolism of PCNB to PCA is common to various microorganisms, but metabolism of PCNB to PCTA is specific for some filamentous fungi. Judging from these findings, it is impossible to elucidate selective action of PCNB from only presence or lack of PCNB degrading ability of microorganisms.