Some Metabolic Responses ofRhizoctonia solanito Napropamide

Abstract

Responses ofRhizoctonia solaniKuhn to napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], were evaluated by measuring whole-cell respiration, mitochondrial respiration, ATP synthesis, and membrane leakage. Whole-cell respiration, measured with an O2electrode, was stimulated in the presence of napropamide at 1.1, 2.2, and 4.4 × 10−5M. Mitochondrial respiration was stimulated at 1.1 × 10−11M, but higher concentrations were inhibitory. The addition of 10−5M napropamide to isolated mitochondria ofR. solaniresulted in reduced ATP synthesis, measured by the firefly luciferase assay, and in increased membrane permeability as measured by increases in electrical conductivity of filtrates fromR. solanigrown in culture medium containing napropamide. These results indicate that, under laboratory conditions, napropamide reduced ATP synthesis, caused membrane leakage, and stimulated respiration inR. solani.

Metabolic activities of the sugarbeet pathogens Fusarium solani (Mart.) Sacc. and Sclerotium rolfsii Sacc. under pyramin stress

“…Of the fractions studied, the amino, peptide and other soluble nitrogen fractions were secreted in appreciable amounts. Similar conclusions were arrived at byKurtz et al (1982) using the herbicide napropamide.Microanalysis of mycelia of both fungi revealed significant decreases in the amounts of nitrate-N, especially at the higher concentrations of pyramin, which might suggest active nitrate reductions and could explain the presence of detectable amounts of ammonium in the mats. The nitrate-reductase enzyme has been detected in non-green tissues (Lee, 1979).…”

“…Increases in respiration rates of some phytopathogenic fungi by many herbicides have been reported by several workers (Harhash, 1977;Kurtz et al, 1982;Naguib and Heikal, 1982;Rodriguez-Kabana and Curl, 1970). The increased rates of CO: evolution by F. solani and S. rolfsii were accompanied by increased amounts of keto acids excreted into the culture media.…”

Inhibition of growth and mycotoxin production of Alternaria alternata inhabiting decayed fruits by pesticides

“…On the other hand, increasing the rate of respiration by toxicants was recorded by McCallan et al [22]. This increase may possibly be due to an increase in membrane permeability to substrate as indicated by Kurtz et al [23].…”