Venus flytraps' metabolome analysis discloses the metabolic fate of prey animal foodstock

Carnivorous plants such as the Venus flytrap Dionaea muscipula survive in nutrient-poor habitats by attracting and consuming animals. Upon deflection of the touch-sensitive trigger hairs, the trap closes instantly. Panicking prey repeatedly collides with trigger hairs, which activate the endocrine system: mechano- and chemosensors translate the information on the prey's nature, size, and activity into jasmonate-dependent lytic enzyme secretion. This digestive fluid gradually degrades its exoskeleton and internal tissues. The released substances are absorbed by glands covering the inner trap surface. To understand Dionaea's modification of metabolism upon prey consumption, we compared the metabolic profiles associated with secretion and insect feeding. In favor of digestive enzyme secretion, the abundance of most amino acids decreased after JA-stimulation without prey present. By contrast, insect feeding resulted in an increase in almost all amino acids within the trap. In agreement with the export of prey-derived nitrogen, the abundance of certain amino acids also increased in the petiole. In response to feeding with urea, chitin, nucleic acids, or phospholipids, the amino acid profile remained relatively unchanged. This might indicate that the alterations in the Venus flytrap's metabolism depend both on the type of substance and on its amount.