Pseudomonas syringae enhances herbivory by suppressing the reactive oxygen burst in Arabidopsis

• Scaptomyza spp. herbivores associate with the phytopathogen Pseudomonas syringae.
• Scaptomyza flava shows enhanced feeding on plants infected with P. syringae.
• P. syringae suppresses the oxidative burst that acts in plant immunity.
• The oxidative burst is involved in plant defense against S. flava.
• Plant defenses induce expression of S. flava oxidative stress tolerance-related genes.

Plant–herbivore interactions have evolved in the presence of plant-colonizing microbes. These microbes can have important third-party effects on herbivore ecology, as exemplified by drosophilid flies that evolved from ancestors feeding on plant-associated microbes. Leaf-mining flies in the genus Scaptomyza, which is nested within the paraphyletic genus Drosophila, show strong associations with bacteria in the genus Pseudomonas, including Pseudomonas syringae. Adult females are capable of vectoring these bacteria between plants and larvae show a preference for feeding on P. syringae-infected leaves. Here we show that Scaptomyza flava larvae can also vector P. syringae to and from feeding sites, and that they not only feed more, but also develop faster on plants previously infected with P. syringae. Our genetic and physiological data show that P. syringae enhances S. flava feeding on infected plants at least in part by suppressing anti-herbivore defenses mediated by reactive oxygen species.

Figure optionsDownload as PowerPoint slide