Volatiles of bacterial antagonists inhibit mycelial growth of the plant pathogen Rhizoctonia solani

Abstract

Bacterial antagonists are bacteria that negatively affect the growth of other organisms. Many antagonists inhibit the growth of fungi by various mechanisms, e.g., secretion of lytic enzymes, siderophores and antibiotics. Such inhibition of fungal growth may indirectly support plant growth. Here, we demonstrate that small organic volatile compounds (VOCs) emitted from bacterial antagonists negatively influence the mycelial growth of the soil-borne phytopathogenic fungus Rhizoctonia solani Kühn. Strong inhibitions (99-80%) under the test conditions were observed with Stenotrophomonas maltophilia R3089, Serratia plymuthica HRO-C48, Stenotrophomonas rhizophila P69, Serratia odorifera 4Rx13, Pseudomonas trivialis 3Re2-7, S. plymuthica 3Re4-18 and Bacillus subtilis B2g. Pseudomonas fluorescens L13-6-12 and Burkholderia cepacia 1S18 achieved 30% growth reduction. The VOC profiles of these antagonists, obtained through headspace collection and analysis on GC-MS, show different compositions and complexities ranging from 1 to almost 30 compounds. Most volatiles are species-specific, but overlapping volatile patterns were found for Serratia spp. and Pseudomonas spp. Many of the bacterial VOCs could not be identified for lack of match with mass-spectra of volatiles in the databases.

Soil Fungistasis Against Fusarium Graminearum Under Different Crop Management Systems

“…Although other studies have shown that from 30 to 60 % of isolates of soil bacteria can produce volatile fungal inhibitors (Zou et al, 2007) and that these bacteria come from very diverse genera, including Bacillus, Micrococcus, Rhizobium, and Xanthomonas (Kai et al, 2007;Zou et al, 2007), this was not observed in our experiments. Hartmann et al (2009) pointed out that the inhibitory capacity of a compound in the soil will depend not only on its specific biochemical effects on a pathogen but also on the ability of the compound to diffuse in the culture media or soil.…”

Bio-suppression of Sclerotinia Stem Rot of Tomato and Biostimulation of Plant Growth Using Tomato-associated Rhizobacteria

“…This result is in agreement with previous findings [52] where 76.59% decrease in S. sclerotiorum growth is obtained using volatile organic compounds. B. subtilis is able to produce volatile elements exhibiting antifungal activity toward R. solani and B. cinerea [53,54].…”

Plant host habitat and root exudates shape soil bacterial community structure

“…Certain bacteria are considered as beneficial, because they produce phytohormones (Azospirillum and Pseudomonas) (Mantelin and Touraine, 2004;Preston, 2004) and antifungal compounds (Stenotrophomonas, Pseudomonas and Microbacterium) (Preston, 2004;Kai et al, 2007;Zachow et al, 2008) or contribute to biogeochemical cycling of sulphur (Acidovorax) (Schmalenberger and Kertesz, 2007) or nitrogen, as diazotrophs and denitrifiers (Azospirillum) (Costacurta and Vanderleyden, 1995). Bacteria considered as human opportunistic pathogens, such as Stenotrophomonas maltophilia, Enterobacter cloacae (Berg et al, 2005) or vine phytopathogenic bacteria, such as Xylophilus ampelinus (Grall and Manceau, 2003), were able to assimilate root exudates and to proliferate in the rhizosphere of different plant species.…”