Metabolism of Edifenphos by Strains of Pyricularia oryzae with Varied Sensitivity to Phosphorothiolate Fungicides

Abstract

Three typical strains of Pyricularia oryzae with varied sensitivity against phosphorothiolate fungicides [sensitive (S), moderately resistant (MR) and resistant (R)] metabolized edifenphos (O-ethyl S, S-diphenyl phosphorodithioate, Hinosan®) at a different rate. The metabolic rate of edifenphos was followed by the order of sensitivity of strains, i. e., S>MR>R. The metabolic sites were (I) P-S bond cleavage (S>MR>R=O), (II) S-C bond cleavage (S≥MR>R=O), and (III) hydroxylation at p-position of phenyl ring (S, MR>R). Among the metabolic pathways, the P-S bond cleavage I is presumed to be responsible for the sensitivity of P. oryzae.