Plant communication/sensing references wanted

Edwin Barkdoll eb3 at
Sat Dec 19 10:44:30 EST 1992

In article <1992Dec18.145440.19868 at> young at writes:
>In article <1992Dec16.001934.23792 at> ajt at writes:
>[...mimosa pulvinus mechanism discussion deleted...]
>>The analogy with propagation of nerve impulses in animals is often
>>cited in descriptions of these responses, and ion-transport is
>>certainly involved in the turgor mechanism of the pulvini.  However,
>>electrogenic proton extrusion is the fundamental ion-transport process
>>in plants and the active Na+/K+ exchanges that occur in transmission of
>>nerve impulses do not occur in plants.

	Active Na+/K+ exchange is not involved in transmission of
nerve impulses.  It is however involved in maintenance of the
electrochemical gradient required for the action potential.

>  This is interesting...apparently there is some disagreement in this area?
>  I lifted the following from a different newsgroup written by Bill Williams
>  of St. Mary's College of Maryland in message <13812 at> in
>  reference to mimosa pudica:
>Sensing of environment:  I'm not too sure what the actual sensing mechanism is,
>but the signal is an action potential, just like in an animal's

	Definitely not "just like in an animal's neurons".
> A
>charge separation propagates along the cells, causing sodium and potassium
>channels in their membranes to open and close, which alters the membrane
>potential and thus passes the signal along to the next patch of membrane. 
>Plant action potentials are usually much, much slower to propagate than animal
>action potentials.

	Something on the order of 1/10^4 as fast!

>  Clearly, there is a fundamental difference of opinion regarding the action
>  of Na+ and K+ in this area...either that, or my ignorance is showing, which
>  is entirely possible.  :-)

	There is no work on action potentials in plants which
approaches the depth of that in animals but there is some evidence
that the primary ions are K+ and Cl- not K+ and Na+.  Don't have a
reference handy but you might look for a review by Simmons (?) in _The
New Phytologist_ I think the year is 1982.  There is probably much
more recent work that I know nothing about.

Edwin Barkdoll
eb3 at

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