Secondary metabolites produced by Propionicimonas sp. (ENT-18) induce histological abnormalities in the sclerotia of Sclerotinia sclerotiorum

Abstract

Sclerotinia sclerotiorum is a highly aggressive pathogen that causes great economic losses, especially in temperate climates. Several biological control agents are available, but actinobacteria have seldom been used to control this fungus. Our objective was to evaluate the efficiency and ultrastructural effects of the secondary metabolites produced by the ant-associated actinobacterium Propionicimonas sp. ENT-18 in controlling the sclerotia of S. sclerotiorum. We demonstrated total inhibition of sclerotia treated with 62.5 lg/10 ll of an ethyl acetate extract of compounds produced by ENT-18, and calculated an LC 50 of 1.69 lg/sclerotia. Histological and ultrastructural analysis indicated that the cells of the treated sclerotia were severely damaged, suggesting direct action of the biomolecule(s) produced by the actinobacterium ENT-18 on the cell structure of the medullae and rind cell wall. This is the first report demonstrating a novel property of Propionicimonas sp.-antifungal activity against S. sclerotiorum.

Biological control of phytopathogenic fungi by endophytic actinomycetes isolated from maize (Zea mays L.)

“…Nevertheless, these discrepancies highlight the need to conduct more research to understand how these endophytic communities interact with maize plants in different edaphoclimatic conditions. Many works have reported positive findings using Streptomyces species for controlling different plant pathogens (Berg et al 2001;Bérdy 2005;Zucchi et al 2008;Zucchi et al 2010). Traditionally, in vitro tests are the first step for screening a new biocontrol candidate with antagonistic activity against the target phytopathogens (Kunoh 2002).…”

Role of Phosphate-Solubilizing Actinomycetes in Plant Growth Promotion: Current Perspective

“…On the contrary, the actinobacteria with their ability to (1) sporulate, (2) transform various complex soil nutrients into simple and accessible forms, (3) extensively and efficiently colonize plant roots, (4) manage phytopathogens, and (5) secrete other plant-growth-promoting substances make these organisms as preferred choices for developing potential field bio-inoculants. Actinomycetes are metabolically flexible soil/rhizosphere-colonizing microorganisms Euanorasetr et al 2010;Lei et al 2013) capable of producing a range of compounds of interest, including (1) antifungal compounds which have been found useful in controlling fungal root diseases (Rothrock and Gottlieb 1984;Zucchi et al 2010;Bungonsiri et al 2011;Sreevidya and Gopalakrishnan 2012;Francisco et al 2013) (2) siderophores (Lee et al 2012;Nakouti et al 2012;Najwa et al 2013), ACC deaminase (El-Tarabily 2008), and (3) plant-growth-promoting hormones (Hamdali et al 2008a;Khamna et al 2010). Generally, plant root exudates stimulate growth, proliferation, and rhizosphere colonization of actinomycetes that may act as a strong antagonist to fungal pathogens.…”

Colonization of Streptomyces felleus YJ1 and Its Effects on Disease Resistant-Related Enzymes of Oilseed Rape

“…etc. were available to prevent Sclerotinia sclerotiorum (Fróes et al, 2012;Tahtamouni et al, 2006;Zucchi et al, 2010).…”