Evaluation of the Inhibitory Effects of Wuyiencin, a Secondary Metabolite of Streptomyces albulus CK-15, Against Sclerotinia sclerotiorum In Vitro

Abstract

Sclerotinia sclerotiorum (Lib) de Bary, a destructive fungal pathogen with an extensive host range, causes various diseases with the potential to cause huge economic losses to crops worldwide. Streptomyces species produce secondary metabolites with variable structures and biological activities that offer possible control methods for crop diseases. Herein, we evaluated the inhibitory effects of Wuyiencin, a secondary metabolite of Streptomyces albulus CK-15, against S. sclerotiorum. The results showed that Wuyiencin markedly inhibited mycelial growth and germination, and the formation of sclerotia. It also increased cell membrane permeability, resulting in leakage of intracellular substances in pathogen mycelia. Wuyiencin markedly decreased oxalic acid (OA) content and the activities of polygalacturonase (PG) and pectin methyl-galacturonic (PMG) enzymes. Moreover, it downregulated Nox1, ITL, pph1, Caf1 and sca1, all genes related to growth and infection. Lesions were smaller and less pronounced on soybean (Glycine max (Linn.) Merr.) leaves pretreated with Wuyiencin in vitro, and the inhibition rate reached 78.36%. The results suggest that Wuyiencin holds promise for the management of diseases caused by S. sclerotiorum, and the findings provide clues on the mechanism of action.

Effects of ε-Poly-L-Lysine Combined with Wuyiencin as a Bio-Fungicide against Botryris cinerea

“…However, when mixed with wuyiencin, not only did the prevention effect improve but also the damage was significantly reduced ( Figure 4 ), which is consistent with the results of previous field trials of ε-PL on strawberries ( Figure S2 ). In addition, wuyiencin has been reported to protect plants by triggering a defense response [ 17 ], which partially explains why the combination of wuyiencin and ε-PL in this study could reduce the harm caused by ε-PL alone in plants.…”

“…Wuyiencin markedly downregulates mycelial growth and spore formation/germination and disturbs mycelium membrane permeability during primary pathogen infection, which additionally induces host plant defense reactions. Moreover, it downregulated the expression of Sclerotinia sclerotiorum growth and infection-related genes [ 17 ]. Herein, we tested the inhibitory effects ε-PL combined with wuyiencin.…”

“…Hence, it would also be significant to screen biocontrol components that have synergistic effects with ε-PL. Wuyiencin is produced by Streptomyces albulus CK-15 and is widely used as an antifungal agent to control various fungal diseases of vegetables and field crops in agriculture [ 17 ]. However, there have been few studies conducted on ε-PL combined with other second metabolites agents from Streptomyces to inhibit plant diseases.…”

Field Application of Wuyiencin Against Sclerotinia Stem Rot in Soybean

“…The S. sclerotiorum fungus infects a broad spectrum of host plants (>600), including soybean, inflicting yield losses of up to 70%. The presence of sclerotia mixed in seed may result in lower seed number and weight, and SSR infection within seed pods may lower oil content and reduce seed germination (Mueller et al, 1999;Yang et al, 2022). The distribution of S. sclerotiorum covers 95 countries and almost every continent, including Africa, Asia, Australasia, Europe, North America, and South America (Saharan and Mehta, 2008;Willbur et al, 2019b).…”

“…This highly effective, broadspectrum, low-toxicity bio-pesticide is mainly used to control a variety of fungal diseases of vegetables, fruits, grains and other crops (Ge et al, 2015;Yang et al, 2021a). In a previous study, we observed that Wuyiencin protects soybean from S. sclerotiorum through antibiosis (inhibition of sclerotia production and germination), but application technologies for controling SSR using Wuyiencin have not been established (Yang et al, 2022).…”