Venus flytraps meet post-capture energy needs with cyclic electron transport

The Venus flytrap is a carnivorous plant native to North American swamplands with low soil fertility. Capture of insects allows the plant to supplement its nutrient and energy intake via absorption through its traps. This adoption of root function by the traps has led to the plant having a reduced root system, as well as low photosynthetic activity, since energy is acquired through other means. Though digestion of prey provides nutrients for both immediate use and longer-term storage, trap closure and prey consumption are energy-intensive in the short term and this need must be met by the plant via adenosine triphosphate (ATP) production.

In a recent study published in Annals of Botany, Daniel Maurer and colleagues attempted to determine by what processes the high energy needs of trap closure and digestion are met. The group measured chlorophyll fluorescence and carbon dioxide uptake via photosynthesis as well as the energy dynamics of the traps, both with and without prey capture.

The group’s findings indicated that the traps shift temporarily from linear to cyclic electron transport in order to produce the additional energy required for energy homeostasis during the early phase of digestion. “Cyclic electron transport in photosynthesis is required when the total demand for ATP exceeds the demand for ATP in basic carbon dioxide fixation reactions,” the authors explain. By four hours after capture, energy from digestion of the insect had begun to contribute to the traps, powering further prey processing. By the time a full day had passed, that acquired energy had begun to be exported preferentially to other organs within the plant, leading to a drop in the ATP content of the traps.

Further research aiming to achieve greater detail in understanding flytrap metabolism will require innovative methodology. “A detailed resolution of continuing metabolic processes, such as transport of prey metabolites, their distribution and early degradation inside the traps,” write the authors, “requires the development of tissue-specific, isotope ratio mass spectrometry-coupled gas chromatography–mass spectroscopy analyses in future studies.”