Project description:Ralstonia solanacearum causes disease in more than 200 plant species including bacterial wilt of tomatoes and brown rot of potatoes. This bacterium is a soilborne and waterborne pathogen, with a worldwide distribution and belongs to the EPPO A2 list of quarantine pathogens. ln the UK, the bacterium is present in the rivers, but its prevalence depends on the season; it is highly abundant in the summer and undetectable during winter. To survive the cold winter temperatures, R. solanacearum overwinters inside plants growing alongside the rivers such as Solanum dulcamara. Solanum nigrum is a closely related species to Solanum dulcamara, and to another susceptible hosts of this pathogen. We assemble the genome of this species to identify differences and similarities between hosts.
Project description: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.
Project description:Plants can respond to insect oviposition but little is known about which responses directly target the insect eggs and how. Here, we reveal a mechanism by which the bittersweet nightshade, Solanum dulcamara, kills the eggs of a generalist noctuid herbivore. The plant responded at the site of oviposition by Spodoptera exigua with neoplasm and chlorotic tissue formation, accumulation of reactive oxygen species and induction of defence genes and proteins. Transcriptome analysis revealed that these responses were reflected in the transcriptional reprogramming of the egg-laden leaf. The plant-mediated egg mortality on S. dulcamara was not present on a genotype lacking chlorotic leaf tissue at the oviposition sites on which the eggs are exposed to less hydrogen peroxide. As exposure to hydrogen peroxide increased egg mortality, while catalase supplementation prevented the plants from killing the eggs, our results suggest that ROS formation directly acts as an ovicidal plant response of S. dulcamara.
