Data from: The whitefly-associated facultative symbiont Hamiltonella defensa suppresses induced plant defenses in tomato

1. Maternally inherited bacterial symbionts are present in many, if not most, insect species. While there is rapidly accumulating evidence that facultative, heritable symbionts often protect insect hosts from natural enemies, there have been few clear examples where facultative symbionts mediate herbivore-plant interactions. 2. The phloem-feeding whitefly, Bemisia tabaci, is a major agricultural pest that frequently harbors facultative symbionts, including Hamiltonella defensa. While H. defensa and other facultative symbionts have been shown to improve whitefly performance on particular food plants, no direct and specific roles for symbiont-mediated interactions with food plants have been identified. 3. Here, we conducted a series of assays to determine whether infection with H. defensa improved whitefly performance on tomato (Solanum lycopersicum) and whether this benefit was associated with symbiont effects on induced plant defenses. Finally, we tested whether impacts on induced defenses involved the modulation of a salivary factor. 4. The down-regulation of plant defenses was associated with increased whitefly fecundity and survival. Feeding by H. defensa-infected whiteflies suppressed JA and JA-related anti-herbivore induced defenses in tomato relative to uninfected controls. That saliva-only treatments of damaged tomato leaves from H. defensa-infected whiteflies suppressed induced plant defenses compared to saliva from uninfected controls, suggested that elicitors in saliva were responsible. Characterization of the putative salivary factor(s) revealed they are likely small (< 3-kDa) and nonproteinaceous. 5. Interestingly, suppression of defenses was not observed in SA-deficient NahG plants, indicating that suppression of JA-regulated defenses depends on the SA-signaling pathway. This finding reveals an intriguing example of the cross-talk between SA and JA signaling pathways and suggests that infection with facultative symbionts can result in the manipulation of induced plant defenses to the benefit of the insect host and heritable symbiont. 6. Our results show that the bacterial symbiont H. defensa mediates whitefly-plant interactions by suppressing induced plant defenses in tomato. This finding is among the first showing a direct role for facultative symbionts in mediating plant-herbivore interactions and demonstrates a novel tactic for insect herbivores to circumvent plant defenses. Symbiont-mediated suppression of plant defenses may enhance the deleterious effects of insect pests feeding on important crops.