|KUMAR, N - Justus-Liebig University|
|HOHENARTER, L - Universitat Hamburg|
|GRAHAM, D - Washington State University|
|KANDEL, S - University Of Washington|
|DOTY, S - University Of Washington|
|MICKNASS, U - Justus-Liebig University|
|KOGEL, K - Justus-Liebig University|
|IMANI, J - Justus-Liebig University|
Submitted to: Journal of Biology and Nature
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2017
Publication Date: 10/7/2017
Citation: Okubara, P.A., Kumar, N., Hohenarter, L., Graham, D., Kandel, S., Doty, S.L., Micknass, U., Kogel, K.H., Imani, J. 2017. Inhibition of plant-interacting microbes by Vegelys®, an allium-based antimicrobial formulation. Journal of Biology and Nature. 8:40-51.
Interpretive Summary: Plant extracts are natural or native sources of compounds for combatting fungal and bacterial plant pathogens. A commercial formulation of three ingredients from garlic and onion, called VEG’LYS or Vegelys, showed activity against a variety of plant pathogens, as well as non-pathogenic bacterial endophytes. The endophytes were the most sensitive and the fungi the least sensitive to the commercial product. Our findings indicate that it has potential as a broad spectrum antimicrobial agent, but that application as a soil fumigant needs to be optimized.
Technical Abstract: Plant extracts offer a natural alternative to synthetic chemicals for the control of unwanted microbes. VEG’LYS®, a commercial formulation of three ingredients from garlic and onion, was developed for surface sterilization of seeds. Here, we show that this product inhibited the growth or development of biotrophic, hemi-biotrophic and necrotrophic plant pathogens, including Blumeria graminis f. sp. hordei, Fusarium graminearum, Botrytis cinerea, Rhizoctonia solani AG-8, Pythium ultimum, Pseudomonas syringae and Ralstonia solanacearum, in laboratory assays. Fungi and oomycetes responded in a species-dependent manner, but their growth generally was inhibited at a concentration of 0.01% VEG’LYS (IC100). For bacterial pathogens, the IC100 ranged from 0.005%-0.05%. The formulation was also tested on beneficial microbial endophytes from poplar and willow. The endophyte isolates, including members of genera Burkholderia, Curtobacterium, and Rahnella, showed IC100 values of 0.0015%-0.0025%, also with genera- or species-dependent responses. The endophytes generally were most sensitive to VEG’LYS relative to the other microbes; however, the growth of two endophyte isolates was stimulated by the product, and a number produced spontaneous variants able to grow on concentrations exceeding the original IC100. These findings suggested that certain endophytes had the potential to adapt to the antimicrobial effects of VEG’LYS. In greenhouse studies, growth of wheat seedling roots was impaired by 0.02% and 0.05% VEG’LYS applied as a soil drench, and the treatment did not reverse root damage caused by the soilborne pathogen R. solani AG-8. Applications of this product in agricultural venues likely will require optimization.