Dimethyl disulfide exerts antifungal activity against Sclerotinia minor by damaging its membrane and induces systemic resistance in host plants

Swati Tyagi,Pratyoosh Shukla,Kui-Jae Lee,Jong-Chan Chae

doi:10.1038/s41598-020-63382-0

Swati Tyagi, Pratyoosh Shukla + Show 2 more

Open Access

https://doi.org/10.1038/s41598-020-63382-0

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Abstract

Microbial volatile compounds (MVCs) significantly influence the growth of plants and phytopathogens. However, the practical application of MVCs at the field level is limited by the fact that the concentrations at which these compounds antagonize the pathogens are often toxic for the plants. In this study, we investigated the effect of dimethyl disulfide (DMDS), one of the MVCs produced by microorganisms, on the fitness of tomato plants and its fungicidal potential against a fungal phytopathogen, Sclerotinia minor. DMDS showed strong fungicidal and plant growth promoting activities with regard to the inhibition of mycelial growth, sclerotia formation, and germination, and reduction of disease symptoms in tomato plants infected with S. minor. DMDS exposure significantly upregulated the expression of genes related to growth and defense against the pathogen in tomato. Especially, the overexpression of PR1 and PR5 suggested the involvement of the salicylic acid pathway in the induction of systemic resistance. Several morphological and ultrastructural changes were observed in the cell membrane of S. minor and the expression of ergosterol biosynthesis gene was significantly downregulated, suggesting that DMDS damaged the membrane, thereby affecting the growth and pathogenicity of the fungus. In conclusion, the tripartite interaction studies among pathogenic fungus, DMDS, and tomato revealed that DMDS played roles in antagonizing pathogen as well as improving the growth and disease resistance of tomato. Our findings provide new insights into the potential of volatile DMDS as an effective tool against sclerotial rot disease.

Highlights

Microbial volatile compounds (MVCs) significantly influence the growth of plants and phytopathogens
The Minimum inhibitory concentration (MIC) of dimethyl disulfide (DMDS) for Aspergillus flavus and Rhizoctonia solani were higher than 50 μM, whereas for other fungi, the values were 50 μM or less (Table 1)
The growth of DMDS-treated fungi was restored when they were re-inoculated on fresh medium but the abnormalities were still seen in the hyphae

Summary

Introduction

Microbial volatile compounds (MVCs) significantly influence the growth of plants and phytopathogens. We investigated the effect of dimethyl disulfide (DMDS), one of the MVCs produced by microorganisms, on the fitness of tomato plants and its fungicidal potential against a fungal phytopathogen, Sclerotinia minor. Microbial volatile compounds (MVCs) have been verified to inhibit the growth of pathogens and to improve the health of plants by inducing a systemic resistance[4,6]. Bacillus and Pseudomonas strains were reported to produce 2,3-butanediol, acetoin, 2-butanone, 2-methyl-n-1-tridecene, albuterol, 1,3 propane-di-ol, and dimethyl disulfide (DMDS), which improved the growth of plants by interfering with plant hormone signaling and induced systemic resistance against plant pathogens[6,8,9,10,11]. MVCs can act as multitrophic signals in ecologically complex systems and can elicit pleiotropic responses[25,26], the practical application of MVCs as alternatives to chemical pesticides requires more information, such as accurate identification and assessment of the bioactive compounds

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