How does the Venus flytrap “count”? – The molecular and evolutionary basis of frequency/dosedependent decision-making in the carnivorous Droseraceae family

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The ability of number estimation or ‘counting’ is ubiquitous in the animal kingdom and involves memorization, rule-following and decision-making. Although plants certainly lack animal´s neuronal structures, the Venus flytrap, Dionaea muscipula, has invaded this animal stronghold. Alike all carnivorous plants, Dionaea depends on an animal diet in its nutrient-poor natural habitat. When an insect visits the Dionaea trap and tilts the mechanosensory trigger hairs on the inner surface, action potentials (APs) are fired and travel along the surfaces of cells. As soon as the moving object elicits two consecutive APs, the trap snaps shut, encaging the victim and initiating Dionaea´s "hunting cycle" (named by Darwin). Within the different steps of the hunting cycle, Dionaea ‘counts’ and ‘memorizes’ the number of action potentials to estimate the size and nutrient content of a struggling prey. Accordingly, Dionaea continuously weighs to continue or to stop its metabolically costly digestive cycle, which allows the Venus flytrap to balance the cost and benefit of hunting. Therefore, Dionaea´s action potential bears quantized information. Aiming to unravel the molecular mechanisms underlying frequency-dependent decision making in carnivorous plants, we will identify the components of the AP as well as the cell types generating and propagating the electrical signal. Using mutants defective in excitation-contraction coupling, we aim to identify the key players responsible for Dionaea´s short-term "Memory". In a comparative genomic approach on selected carnivorous plant species, we aim to identify molecular circuits providing the cellular basis for "counting", hapto-electric signalling and decision-making.