Volatiles produced by soil‐borne endophytic bacteria increase plant pathogen resistance and affect tritrophic interactions

Abstract

Volatile organic compounds (VOCs) released by soil microorganisms influence plant growth and pathogen resistance. Yet, very little is known about their influence on herbivores and higher trophic levels. We studied the origin and role of a major bacterial VOC, 2,3-butanediol (2,3-BD), on plant growth, pathogen and herbivore resistance, and the attraction of natural enemies in maize. One of the major contributors to 2,3-BD in the headspace of soil-grown maize seedlings was identified as Enterobacter aerogenes, an endophytic bacterium that colonizes the plants. The production of 2,3-BD by E. aerogenes rendered maize plants more resistant against the Northern corn leaf blight fungus Setosphaeria turcica. On the contrary, E. aerogenes-inoculated plants were less resistant against the caterpillar Spodoptera littoralis. The effect of 2,3-BD on the attraction of the parasitoid Cotesia marginiventris was more variable: 2,3-BD application to the headspace of the plants had no effect on the parasitoids, but application to the soil increased parasitoid attraction. Furthermore, inoculation of seeds with E. aerogenes decreased plant attractiveness, whereas inoculation of soil with a total extract of soil microbes increased parasitoid attraction, suggesting that the effect of 2,3-BD on the parasitoid is indirect and depends on the composition of the microbial community.

Identification and determination of characteristics of endophytes from rice plants and their role in biocontrol of bacterial blight caused by Xanthomonas oryzae pv. oryzae

“…Enterobacter cloacae and Enterobacter aerogenes strains have been reported to control Fusarium oxysporum f. sp. spinaciae in spinach (Tsuda et al, 2001) and Setosphaeria turcica, the Northern corn leaf blight fungus, in maize (D'Alessandro et al, 2014). Biological control action of E. cloacae has also been reported by Roberts et al (1994).…”

Sweet scents from good bacteria: Case studies on bacterial volatile compounds for plant growth and immunity

“…In animals and plants, BVCs function as elicitors and suppressors of immune responses respectively (Hsieh et al 2007;Rudrappa et al 2010). A test of several 2,3-butanediol stereoisomers indicated that only (2R,3R)-2,3-butanediol promoted plant growth and induced resistance/tolerance (Ryu et al 2004a, b;Han et al 2006;Cho et al 2008;D'Alessandro et al 2014). Intriguingly some insects also utilize acetoin and 2,3-butanediol as pheromones and kairomones (Buttery and Ling 1984;Nout and Bartelt 1998;Moore and Moore 1999;Moore et al 2002;Robacker and Lauzon 2002;Rochat et al 2002;Bengtsson et al 2009).…”

The Green Roof Microbiome: Improving Plant Survival for Ecosystem Service Delivery

“…For example, Actinobacteria are well-known for antibiotic production and among most commonly encountered members of endophytic bacterial communities (Rosenblueth and Martínez-Romero, 2006) The production of secondary metabolites produced by plant-associated Actinobacteria are currently understudied (Brader et al, 2014). Some microbes can also lessen the amount of volatile organic compounds emitted that are used by herbivores and parasites to orient toward host plants (e.g., the green roof vegetation) (D'Aleessandro et al, 2014).…”