D3079: Soaked in stressors: Gene expression in two heirloom tomatoes under flooding and herbivory

Climate change is exacerbating many plant stressors. Although plants actively respond, it is unclear how they react to combinatorial stressors, particularly flooding and insect herbivory.

We investigated plant chemistry and gene expression changes in two heirloom tomato varieties under flooding, herbivory, and their combination. After three days of flooding, third instar Spodoptera exigua larvae began feeding on tomato leaves and fed for 48 hours. Our study demonstrated flooding and the combination of flooding and herbivory increased emission of volatile organic compounds (VOCs), especially terpenes. Terpenes are important herbivore-induced VOCs, known to deter herbivores, and attract predators and parasitoids.

Under herbivory alone, altered gene expression was minimal, but flooded plants exposed to herbivory showed differential gene expression between varieties. One tomato variety (Cherokee Purple) showed downregulated stress response proteins while the other variety (Striped German) showed a disproportionately large number of upregulated heat-shock proteins. Heat-shock proteins help plants to endure biotic and abiotic stresses. This highlights the importance of understanding plant-insect interactions in combination with climate change-related abiotic stressors, to increase food security.