Mode of action of oxathiin systemic fungicides. IV. Effect of carboxin on solute leakage from hyphae of Rhizoctonia solani

Abstract

Mycelial discs of Rhizoctonia solani were treated with the oxathiin systemic fungicide carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) at 10−4 M to determine the effect upon fungal plasma membranes. Electrical conductance was used as a preliminary monitor for cell leakage. Carboxin treatment consistently resulted in the release of ionic materials. Potassium ions, organic acids, and phosphate-containing materials were exuded from cells treated with carboxin. Phosphate losses were sufficient to retard, but not to stop, further growth of the organism after removal of the fungicide and placement of the mycelium on a growth medium lacking phosphate. Starvation of mycelial discs in deionized water markedly reduced respiratory metabolism and carboxin treatment after starvation did not result in cell leakage, thus indicating that membrane damage did not occur. Nystatin, a known disrupter of membranes, did cause leakage from starved cells. Inasmuch as carboxin is known to inhibit respiratory metabolism, organic acids and phosphate-containing materials may accumulate in treated cells and then be exuded as a secondary effect.

Integrated effect of microbial antagonist, organic amendment and fungicide in controlling seedling mortality (Rhizoctonia solani) and improving yield in pea (Pisum sativum L.)

“…Organic amendment such as mustard oilcake produces volatile and nonvolatile substances during their decomposition and stimulates resident and introduced antagonist-suppressing pathogenic fungi in the soil [51,52]. As regards the mode of action of Carboxin fungicide, it has been known as a strong inhibitor of succinic dehydrogenase enzyme in mitochondria and causing solute leakage (e.g., potassium ions, organic acids, and phosphate-containing materials) from hyphae of R. solani [53,54].…”

Study of the depuration efficiency and microbiology of biobed systems which receive pesticide contaminated effluents from various agro-food processing units

“…2.1.1.1 CARBOXIN 5,6-dihydro-2-methyl-1,4-oxathiine-3-carboxanilide or carboxin (CBX) is a carboxanilide fungicide that is commonly used for seed coating in cereals and crops Srinivas et al, 2017). CBX was the first succinate dehydrogenase inhibitor that was introduced in the market in 1969 and is still in use (S. Shively and Mathre, 1971). It is a systemic fungicide that is recommended for use in small grain cereals (wheat, soybean, barley, oat) against stem rot, whose causal agent is Sclerotium rolfsii (Rakholiya, 2015;Akgül et al, 2011;United States, Environmental Protection Agency, 2004), rust which is caused by basidiomycetes and rhizoctonia diseases (Yanase et al, 2007).…”