Location: Fruit and Tree Nut ResearchTitle: Antifungal activity of Xenorhabdus spp. and Photorhabdus spp. metabolites and volatiles on the soilborne plant pathogenic Sclerotinia sclerotiorum
|CHACON-OROZCO, JULIE - Instituto Biologicio - Brazil|
|BUENO, CESAR - Instituto Biologicio - Brazil|
|Shapiro Ilan, David|
|HAZIR, SELCUK - Adnan Mederes University|
|LEITE, LUIS - Instituto Biologicio - Brazil|
|HARAKAVA, RICARDO - Instituto Biologicio - Brazil|
Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2020
Publication Date: 11/26/2020
Citation: Chacón-Orozco, J.G., Bueno, C.J., Shapiro-Ilan, D., Hazir, S., Leite, L.G., and Harakava, R. 2020.Antifungal activity of Xenorhabdus spp. and Photorhabdus spp. against the soybean pathogenic Sclerotinia sclerotiorum. Scientific Reports, 10, Article number: 20649.
Interpretive Summary: White mold disease is a severe malady with a wide host range including soybeans, cotton numerous vegetable and fruit crops (such as peaches). Generally, chemical fungicides are used to control this disease. However, due to issues of fungicide resistance and environmental concerns related to chemical fungicide use, alternative measures are needed for control of white mold disease. Bacteria in the genera Xenorhabdus and Photorhabdus produce natural metabolites (by-products) that can suppress certain plant diseases. These bacteria are symbionts of beneficial insect-killing nematodes (which are used as bio-insecticides). In this laboratory study we tested 16 strains of Xenorhabdus and Photorhabdus bacteria for their ability to control white mold disease. We found that metabolites from the bacteria called Xenorhabdus szentirmaii was the most toxic to white mold disease. Additionally, we discovered the volatile organic compounds (gases released from the bacteria) were also toxic to the white mold fungus. Our findings indicate potential for using symbiotic bacteria as a new safe method to control white mold disease. Furthermore, this is the first study to demonstrate that volatile organic compounds from Xenorhabdus bacteria can cause plant disease suppression.
Technical Abstract: The fungus, Sclerotinia sclerotiorum, causes white mold disease and infects a broad spectrum of host plants (> 500), including soybean with yield losses of up to 70%. Biological control is a potential alternative for management of this severe plant pathogen. The symbiotic bacteria of entomopathogenic nematodes, Xenorhabdus spp. and Photorhabdus spp., are characterized by the production of antimicrobial compounds, which could serve as potential sources for new bio-fungicides. The objectives of this study were to assess cell-free supernatants (CFS) of 16 strains of these bacteria cultures on S. sclerotiorum mycelium growth; assess the volatiles of X. szentirmaii cultures on the fungus mycelium and sclerotium inhibition; and evaluate the X. szentirmaii cultures as well as their CFS on the protection of soybean seeds against the white mold disease. Among the 16 strains, CFS of X. szentirmaii showed the highest fungicidal effect on growth of S. sclerotiorum. CFS of X. szentirmaii and the volatile generated by the bacterium culture inhibited fungus growth or its consequent production of sclerotia. Our findings indicate potential for a safe and novel control method S. sclerotiorum. Moreover, this is the first study to indicate that volatile organic compounds from Xenorhabdus spp. can be used in plant disease suppression.