Do plants conduct signal mechanism? And if they are conducting the signal through proteins or any biomolecule, do they conduct it in a specific channel like the neural network in the animal kingdom. I wonder, what they have in place of neurons? Some of us might actually think why do in the first place need them. They are not ruled by one king, like our brain.
As a plant physiologist I know Neurons as long cells capable of transmitting a electric signal as a charge change along their membrane. In plants we might consider phloem cells as the counterparts or equivalent to neurons. These are long continuum of cytoplasm which are formed from merging of adjacent cells and are present in nearly all plant organs extending from roots to shoots. In addition plant posses a mechanism of sudden polarity changes in membrane in response to controlled entrance of Ca ions and this polarity change can travel fast across the membrane and creates some known fast responses in plants.
Therefore the basic elements for creation of a neuron counterpart system in plants is ready; but through the evolution, plants didn't need to develop such a fast responding mechanism that is necessary in moving animals. Their concept is to stay in one place and try to adopt in a long time so their response system to environment has been adequate from an evolutionary point of view. Neglecting the some transient environmental stimuli could have been an advantage even. However as Aaron mentioned, those plants that had found an evolutionary advantage in development of such systems, like insectivorous plants, could surpass their fast preys in response time.
The only innervated plants I know of are the venus flytrap and the sleeping fern. The venus flytrap has... well basically nerves in which the action potential is generated when hairs on the flytrap are triggered by an insect. It causes water to move across a membrane in the plant which closes its petals rapidly. The sleeping fern does something similar minus the teeth/digestion.
Plant signalling is huge area of modern biochemistry and physiology of plants. As example you can read about ethylene signalling through MAPK cascade. I mean something like that http://www.sciencemag.org/site/feature/data/plants2001/PDFs/268-5211-667.pdf
and the review:
http://www.plantcell.org/content/14/suppl_1/S3.full
As a plant physiologist I know Neurons as long cells capable of transmitting a electric signal as a charge change along their membrane. In plants we might consider phloem cells as the counterparts or equivalent to neurons. These are long continuum of cytoplasm which are formed from merging of adjacent cells and are present in nearly all plant organs extending from roots to shoots. In addition plant posses a mechanism of sudden polarity changes in membrane in response to controlled entrance of Ca ions and this polarity change can travel fast across the membrane and creates some known fast responses in plants.
Therefore the basic elements for creation of a neuron counterpart system in plants is ready; but through the evolution, plants didn't need to develop such a fast responding mechanism that is necessary in moving animals. Their concept is to stay in one place and try to adopt in a long time so their response system to environment has been adequate from an evolutionary point of view. Neglecting the some transient environmental stimuli could have been an advantage even. However as Aaron mentioned, those plants that had found an evolutionary advantage in development of such systems, like insectivorous plants, could surpass their fast preys in response time.
I checked the literature and found many, among those I suggest this one
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2634336/ in which you can see the concept and Ca triggered responses, and this one;
"Bio-inspired design of intelligent materials", Proc. SPIE 5051, Smart Structures and Materials 2003: Electroactive Polymer Actuators and Devices (EAPAD), 54 (July 28, 2003); doi:10.1117/12.484425; http://dx.doi.org/10.1117/12.484425
In which the mechanical aspect is covered well.
Both have suggested plasmodesmata as the carriers of signal, however, I believe that while it might be the case for transfer of depolarization charge to adjacent cells but we may consider phloem as a better candidate specially for coordinated long distance travel of depolarization wave inside plant tissue through their continuum of cytoplasm and cell membrane.
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