Antifungal activity of tautomycin and related compounds against Sclerotinia sclerotiorum

Abstract

The potential of tautomycin to control oilseed rape stem rot was investigated in this paper. Tautomycin produced by Streptomyces spiroverticillatus strongly inhibited Sclerotinia sclerotiorum, which causes oilseed rape stem rot. Tautomycin showed great inhibition of the mycelial growth of S. sclerotiorum on potato dextrose agar (PDA) plates. The values of EC 50 and MIC were 3.26Â10 À4 mM and 6.52Â10 À4 mM, respectively. Tautomycin treatment also resulted in morphological abnormalities of S. sclerotiorum such as hyphal swellings and abnormally branched shapes, which were observed microscopically. Sclerotia of S. sclerotiorum soaked in the tautomycin solution for 24 h remained viable, but their ability to undergo myceliogenic germination on PDA plates was completely inhibited when the concentration of tautomycin reached 6.52Â10 À4 mM. Tautomycin-treated oilseed rape leaves were found to have a low incidence of leaf blight caused by S. sclerotiorum. The activity of the protein phosphatase (PP) in S. sclerotiorum decreased by 41.6% and 52.6% when treated with 3.30Â10 À4 mM and 6.52Â10 À4 mM tautomycin, respectively. Cellular constituents also leaked from S. sclerotiorum cells incubated with tautomycin. The results suggest that the antimicrobial activity of tautomycin is due to the inhibition of the PP and then a change of membrane permeability. This paper also investigated related compounds that possess either a maleic anhydride or maleic acid moiety. Results showed 2,3-dimethylmaleic anhydride, diphenylmaleic anhydride and dimethyl maleate demonstrated significant activity against S. sclerotiorum. The values of EC 50 for these three compounds were 0.31 mM, 0.15 mM and 3.99 mM, respectively. The MIC values obtained for these compounds were 1.11 mM, 0.56 mM and 9.58 mM, respectively.

Synthesis and antifungal evaluation of a series of maleimides

“…The N ‐substituted maleimides were synthesised by employing two methods according to an improved procedure based on reported methods using maleic anhydrides and amines as the starting materials (Scheme ).…”

“…The in vitro antifungal activities of 63 compounds against S. sclerotiorum were assayed on solid medium PDA using the mycelium growth rate method . These maleimides, dicloran and procymidone were dissolved in 0.1% (m/v) Tween‐80 while mixing with PDA to generate a series of concentrations in the final test solution of 0.39, 0.78, 1.56, 3.13, 6.25, 12.50, 25, 50, 100 and 200 µg mL −1 by the twofold broth dilution method.…”

“…It has been one of the most non‐specific, omnivorous and successful plant pathogens. Its host range includes approximately 400 primarily dicotyledonous plant species . Therefore, S .…”

The Mechanism of Antifungal Action of a New Polyene Macrolide Antibiotic Antifungalmycin 702 from Streptomyces padanus JAU4234 on the Rice Sheath Blight Pathogen Rhizoctonia solani

“…A 5-mm inoculum plug was inoculated with the mycelium at the center of the dishes. The number of sclerotia was counted and the average number of the three PDA plates was calculated after 3-13 days at 28° C [7]. There were nine dishes (replicates) for each treatment.…”

“…solani around each sclerotium were recorded after incubation at 28° C for 2, 3 and 4 days. A sclerotium was considered to have germinated when white and cottony mycelia appeared on the sclerotial surface or on the agar medium [7]. The experiment was repeated for three times.…”