Effects of Drought and Flooding on Herbivore-Triggered Transcriptomic Response in Solanum dulcamara

We use Solanum dulcamara subjected to drought or flooding and damaged by Spodoptera exigua to analyze such interactions at multiple levels. Drought and herbivory caused comparable effects on S. dulcamara physiological response, which was reflected by a considerable overlap in S. dulcamara transcriptomic profiles. This included many defense responses and genes involved in biosynthesis of secondary metabolites that were induced by drought and herbivory but repressed by flooding. Furthermore, combination of drought and herbivory additively induced a part of these herbivore-induced responses suggesting that drought-stressed plants were more resistant. Our study provides concrete evidence of how abiotic stresses differentially affect the plant complex hormonal interactions to fine-tune plant responses to insects. Overall design: Plants were under 3 water treatments (control, drought and flooding) for 5 days before subjected to 2 insect treatments (with 48-h herbivory by Spodoptera exigua (BAW) or without it (no)). 3 biological replicates per treatment combination, 18 in total.