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

在动物界，数字估计或“计数”的能力是无处不在的，它涉及记忆、遵守规则和决策。尽管植物确实缺乏动物的S神经元结构，但捕蝇器Dionaea Muscipula已经入侵了这个动物的大本营。与所有食肉植物一样，Dionaea在其营养不良的自然栖息地依赖动物饮食。当昆虫访问Dionaea陷阱并倾斜内表面的机械感官触发毛发时，动作电位(AP)被激发并沿细胞表面传播。一旦移动的物体引起两个连续的AP，陷阱就会关闭，包围受害者，并启动狄奥娜的S“狩猎周期”(达尔文命名)。在捕猎周期的不同步骤中，Dionaea会‘计算’并‘记忆’动作电位的数量，以估计挣扎中的猎物的大小和营养含量。因此，Dionaea不断权衡是否继续或停止其代谢代价高昂的消化周期，这使得捕蝇器能够平衡狩猎的成本和收益。因此，Dionaea的S动作电位具有量化信息。为了揭开肉食性植物频率相关决策的分子机制，我们将识别AP的成分以及产生和传播电信号的细胞类型。利用兴奋-收缩偶联缺陷的突变体，我们的目标是确定导致Dionaea的S短期“记忆”的关键因素。在对选定的食肉植物物种的比较基因组学方法中，我们的目标是识别分子电路，为“计数”、半电信号和决策提供细胞基础。

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.