Signaling types in Dionaea muscipula prey interaction and capture

Published by on October 18, 2021

Dionaea muscipula, the infamous Venus fly trap, is perhaps the most well-known carnivorous plant on the planet. D. muscipula has been described by Charles Darwin as “the most wonderful plant in the world” because of its unique structure and feeding strategy (Darwin and Darwin, 1888). The anatomical design of this species consists of a pair trapezoid shaped leaves, hinged down the center, and lined with long protruding, needle-like structures (Figure 1A) (Quammen, 1988). This plant is the only species of its kind and its specific morphology evolved in response to resource competition for nitrogen within the plant’s native habit of the Carolinas (Quammen, 1988).

The method with which the D. muscipula entraps its prey is well know. The more interesting part is how this happens. The plant’s structure allows it to attract then interact with its prey before consumption to determine if the cost of digestion will be balanced by the nutrition gained in the process (Quammen, 1988). During daylight hours, over 60 different volatile organic compounds, mimicking the smell of fruits and flowers, are emitted (Kreuzwieser et al., 2014). In addition to the volatile chemical signaling, the plant also releases a clear nectar from glands within the leaves (Quammen, 1988). Both the airborne chemical communication and physical release of nectar attract insects; once a prey item lands within the lobes of the plant, it is assessed. This assessment includes additional chemical signaling by D. muscipula to identify if the item within its grasp is indeed food. Then, the size of the prey is measured since the trap will only close if the prey item is large enough to be beneficial. This is done using mechanical stimuli via small hairs on the inner lobes between the nectar glands (Figure 1B (I))(Volkov, Adesina and Jovanov, 2007; Quammen, 1988). Two distinct touches on one or more hairs is required to spring the lobes closed, as long as they are between one and 20 seconds apart. The spacing of the hairs ensures that only a larger insect could trigger the system (Quammen, 1988).

Figure 1. (A) Image of adult D. muscipula, where the red is the inside of the lobes lined with spines. The lobes hinge to close when mechanically stimulated by trigger hairs (B (I)). Electrical signal is generated via mechanosensitive ion channels causing an action potential (AP) (II), leading to the closure of the leaves and chemical digestion of prey (III) (Kutschera and Briggs, 2009).

The simulation of the hairs is recognized by mechanosensitive channels within the surrounding cells (Volkov, Adesina and Jovanov, 2007). These channels are able to move calcium and potassium cations in and out of cells in response to mechanical stress and the information is conducted through an electrical signal similar to an action potential found in animals (Figure 1B (II). The duration of the action potential in the D. muscipula is approximately 1.5 milliseconds and requires an average electrical charge of 13.6 microcoulombs. The mechanical stimulation of the two hair touches within the 20 second interval induces electrical signals that meet the threshold level, in turn generating the action potential within the motor cells responsible for the movement of the upper regions of each leaf. The action potential signals the leaves to close; the prey item is then trapped within the two lobes and digestive juices containing proteinase break down the insect in order to absorb its nutrients (Figure 1B(III)) (Quammen, 1988).  

The extensive interaction D. muscipula has with its prey demonstrates its almost economical behaviour developed as a result of its evolution in a resource limited environment. This makes the plant’s use of chemical and mechanical signaling all the more important in ensuring its potential prey is fit for consumption.

Resources

Darwin, C. and Darwin, S.F., 1888. Donaea muscipula. In: Insectivorous Plants. London: William Cloves and Sons, Limited. pp.231–259.

Kreuzwieser, J., Scheerer, U., Kruse, J., Burzlaff, T., Honsel, A., Alfarraj, S., Georgiev, P., Schnitzler, J.-P., Ghirardo, A., Kreuzer, I., Hedrich, R. and Rennenberg, H., 2014. The Venus flytrap attracts insects by the release of volatile organic compounds. Journal of Experimental Botany, 65(2), pp.755–766. https://doi.org/10.1093/jxb/ert455.

Kutschera, U. and Briggs, W., 2009. Photograph of an adult Venus flytrap. [image online] Available at: <https://www.researchgate.net/figure/Photograph-of-an-adult-Venus-flytrap-Dionaea-muscipula-a-plant-that-responds-to_fig3_26862801> [Accessed 24 Oct. 2021].

Quammen, D., 1988. The Flight of the Iguana: A Sidelong View of Science and Nature. 1st ed. New York: Delacorte Press.

Volkov, A.G., Adesina, T. and Jovanov, E., 2007. Closing of Venus Flytrap by Electrical Stimulation of Motor Cells. Plant Signaling & Behavior, 2(3), pp.139–145. https://doi.org/10.4161%2Fpsb.2.3.4217