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Venus_flytrap.jpg“Springing the Trap”

In the previous post I suggested that the Venus flytrap works something like a mousetrap. And I described how the “trap” is hydraulically set. (For a more thorough explanation of how the Venus flytrap snaps, please see PDF file here).

But how do the trigger-hairs on the surface of the flytrap’s leaves act to “spring the trap”?

Briefly, the mechanical movement of the trigger-hairs protruding from the leaf activates mechanosensitive ion channels and generates receptor potentials that induce an action potential.

This action potential travels to the midrib of the leaf where it promotes the opening of water channels called aquaporins. This facilitates the rapid water efflux from key cells that hydraulically control the leaf opening.

More simply put, the stimulation of the leaf hairs produce electrical signals that cause the rapid deflation of the water-pressurized cells that keep the leaves open. And, thus, the “trap is sprung”.

(Please see here and here for some recent information regarding the the kinetics and mechanism of the Venus flytrap.)

ligtning_plants.jpgElectrical Signals in Plants?

Do plants have a nervous system?

The short answer is: no. (At least not the complex nervous system of animals.)

But scientists have been able to detect transient electrical signals somewhat analogous to action potentials under certain situations in plants.

Such situations involve the classic examples of thigmosnasty in plants, namely, the “touch-sensitive” plant (Mimosa pudica) and the Venus flytrap.

Charles Darwin described the Venus flytrap plant as “…one of the most wonderful in the world.” on page 231 of his book Insectivorous Plants.

Sparked by a correspondence with Darwin, which included some Venus flytrap plants, the English physiologist John Scott Burdon-Sanderson was the first to discover action potentials in plants following stimulation of a leaf. (Please see reference 1 below.)

electricity_plants.jpgDo Plants Have a Neural Net?

In addition to thigmosnastic plants, all vascular plants may be utilizing electrical signals to regulate a variety of physiological functions.

Many of the biochemical and cellular components of the neuromotoric system of animals has been found in plants. And this has led to the hypothesis that a simple neural network is present in plants, especially within phloem cells, which is responsible for the communication over long distances.

“The reason why plants have developed pathways for electrical signal transmission is most probably the necessity to respond rapidly to external stimuli, for example, environmental stress factors.” (from ref 2 below)

More regarding electrical communication in plants: Novel electrical signals in plants induced by wounding

The Emerging Field of Plant Neurobiology

In 2006, an article was published in the journal Trends in Plant Science that elicited quite a kerfuffle.

This review (PDF) introduced, to the plant scientific community at least, the field of “Plant Neurobiology”. Although this proposal was not without controversy (PDF), the Society for Plant Neurobiology seems to be alive and well (Plant Neurobiology Website). (And if you happen to be in Kitakyushu, Japan, in May this year, you may be able to attend the 6th International Symposium on Plant Neurobiology).

Bottom line: Though plants don’t have a nervous system like animals, plants do have the necessary electrical, biochemical, and cellular components indicative of a neural network, albeit a relatively simple one.

References:
1. Burdon-Sanderson J. (1873) Note on the electrical phenomena which accompany irritation of the leaf of Dionaea muscipula. Proceedings of the Royal Society of London 21, 495–496.
2. Fromm, J. & S. Lautner (2007) Electrical signals and their physiological significance in plants. Plant, Cell and Environment 30, 249-257. (PDF)

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4 Responses to “Nervous Plants 2 – Plant “Neurobiology””

  1. [...] paio di concisi tutorial per spiegare che a) le piante non hanno un sistema nervoso però b) usano segnali elettrici per comandare movimenti basati sullo spostamento di [...]

  2. Susan says:

    Hi,
    I’m looking for people doing research on the effects of high voltage on plant growth. Do you know of anyone?
    thanks,
    Susan

    • plantguy says:

      I don’t know of any such research, but try searching Google Scholar. Using the Advanced Search, try using key words “botany”, “electrostatic”, “voltage”, the phrase “high voltage” or all in combination. Be sure to search only in the biological sciences (check the box on the advanced search page) in order to limit results.
      Good luck!

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