Non‐pathogenic rhizobacteria interfere with the attraction of parasitoids to aphid‐induced plant volatiles via jasmonic acid signalling

Abstract

Beneficial soil-borne microbes, such as mycorrhizal fungi or rhizobacteria, can affect the interactions of plants with aboveground insects at several trophic levels. While the mechanisms of interactions with herbivorous insects, that is, the second trophic level, are starting to be understood, it remains unknown how plants mediate the interactions between soil microbes and carnivorous insects, that is, the third trophic level. Using Arabidopsis thaliana Col-0 and the aphid Myzus persicae, we evaluate here the underlying mechanisms involved in the plant-mediated interaction between the non-pathogenic rhizobacterium Pseudomonas fluorescens and the parasitoid Diaeretiella rapae, by combining ecological, chemical and molecular approaches. Rhizobacterial colonization modifies the composition of the blend of herbivore-induced plant volatiles. The volatile blend from rhizobacteria-treated aphid-infested plants is less attractive to an aphid parasitoid, in terms of both olfactory preference behaviour and oviposition, than the volatile blend from aphid-infested plants without rhizobacteria. Importantly, the effect of rhizobacteria on both the emission of herbivore-induced volatiles and parasitoid response to aphid-infested plants is lost in an Arabidopsis mutant (aos/dde2-2) that is impaired in jasmonic acid production. By modifying the blend of herbivore-induced plant volatiles that depend on the jasmonic acid-signalling pathway, rootcolonizing microbes interfere with the attraction of parasitoids of leaf herbivores.

Virulence Factors of Geminivirus Interact with MYC2 to Subvert Plant Resistance and Promote Vector Performance

“…The compounds were expressed as percentages of peak areas relative to the internal standard (camphor) per 18 h of trapping using one plant. The volatiles of Arabidopsis were collected and analyzed as described previously (Pineda et al, 2013), with minor modification. Volatile trapping was done for 3 h at a flow of 300 mL/min, and the gas chromatography oven temperature program was as follows: 40°C for 2 min, raised at 10°C/min to 280°C, and then held for 4 min.…”

Third-party mutualists have contrasting effects on host invasion under the enemy-release and biotic-resistance hypotheses

“…Leaf chemistry is a key component of many plant herbivore interactions and studies have found that soil microbes alter the leaf chemistry of their host plants (Meiners et al 2017). Pseudomonas fluorescens colonization induced systemic resistance in Arabidopsis, which significantly reduced the growth of the herbivore S. exigua, but it also changed the composition of volatiles induced by the generalist aphid, Myzus persicae, making the plant less attractive to the aphids' natural enemies (Van Oosten et al 2008;Pineda et al 2013;Sugio et al 2015).…”

Plant responses to multiple herbivory : phenotypic changes and their ecological consequences

“…We have focused on aboveground plant vegetative tissues because most information on community processes is available for insect communities associated with vegetative plant shoots. However, similar systemic effects are expected when including the belowground tissues (Soler et al, 2013). Including belowground interactions will be important, even when it further increases the complexity of the interactions and therefore the difficulty of understanding the effects of a phenotypically plastic plant on the development of the associated community.…”

“…Herbivorous insects are connected by both local and systemic plant-mediated interactions. Systemic effects may involve both roots and shoots (Soler et al, 2013) or leaves and flowers (Kessler et al, 2011;Lucas-Barbosa et al, 2011). We have focused on aboveground plant vegetative tissues because most information on community processes is available for insect communities associated with vegetative plant shoots.…”

“…This suggests that higher concentrations of HIPV do not necessarily result in increased attraction, which has been reported for other biotic interactions as well. For example, root colonization with nonpathogenic rhizobacteria modified the composition of the volatile blend induced by aphids; most of the compounds were emitted in larger amounts by plants co-infested with rootcolonizing rhizobacteria plus aphids than by plants only infested with aphids (Pineda et al, 2013). However, the aphid parasitoid (Diaeretiella rapae) preferred the volatile blend from aphid-infested plants without rhizobacteria over the blend from rhizobacteria-treated and aphid-infested plants (Pineda et al, 2013).…”