RESPIRATORY CHARACTERISTICS IN PYRICULARIA-ORYZAE EXPOSED TO A NOVEL ALKOXYIMINOACETAMIDE FUNGICIDE

(E)-2-Methoxyimino-N-methyl-2-(2-phenoxyphenyl) acetamide (SSF-126) in hibited respiration of Pyricularia oryzae mycelia by blockade of the e lectron flux through the cytochrome be, segment of the mitochondrial r espiratory chain. However, the mycelia again began to respire at 20 mi n after treatment. The recovered respiration was sensitive to salicylh ydroxamic acid, a potent inhibitor of cyanide-resistant respiration, b ut not to potassium cyanide, indicating that SSF-126 had the ability t o induce cyanide-resistant respiration in P. oryzae. The recovered res piration was partially linked to energy transduction because SSF-126 c ould not completely suppress the mycelial growth. SSF-1?G caused a rap id depletion of ATP content, but the ATP levels showed recovery, resul ting in improvement of energy charge values. However, the total adenyl ate pool gradually decreased, resulting in only 60% remaining 48 h aft er treatment. SSF-126 markedly suppressed the mycelial growth, the dur ation for mass doubling in cultures incubated with SSF-126 being 2.4 t imes that in the control ones. Thus, SSF-126 works deleteriously on th e supply of metabolic energy in P. oryzae.