Natures wonders: Plant awareness with glutamate (Introduction)

by David Turell , Friday, April 12, 2019, 22:31 (1842 days ago) @ dhw

Just as in animals glutamate is used in plant responses:

https://mindmatters.ai/2019/04/researchers-yes-plants-have-nervous-systems-too/

"Recently, a research team observed the outcome of wounding a plant called Arabidopsis thaliana, a mustard often used in experiments. The really remarkable part is that “these channels are activated by extracellular glutamate, a well-known mammalian neurotransmitter”:

"This study combines genetic and imaging approaches to reveal a rapid and long-distance signaling pathway that communicates leaf damage to intact leaves that are spatially and developmentally distant from the wounded leaf. Toyota et al. detect increased calcium signals at the site of both herbivore and mechanical wounding within 2 s and in distant leaves within 2 min after damage. This signal moves through the plant vasculature at rates of ~1 mm/s, which is faster than can be explained by diffusion.

“'Faster than can be explained by diffusion” means that the transmission appears to be a signal rather than simply the normal course of diffusion in plants. Muday and Brown-Harding explain that in mammals, glutamate receptors speed neurotransmission and in plants they may enable quicker signals to distant parts of the plant. Many details remain to be filled in, of course:

"Future experiments are needed to resolve whether glutamate is moving long distances rather than acting via the localized release and long-distance propagation of ionic signals.

***

"Abstract: Animals require rapid, long-range molecular signaling networks to integrate sensing and response throughout their bodies. The amino acid glutamate acts as an excitatory neurotransmitter in the vertebrate central nervous system, facilitating long-range information exchange via activation of glutamate receptor channels. Similarly, plants sense local signals, such as herbivore attack, and transmit this information throughout the plant body to rapidly activate defense responses in undamaged parts. Here we show that glutamate is a wound signal in plants. Ion channels of the GLUTAMATE RECEPTOR–LIKE family act as sensors that convert this signal into an increase in intracellular calcium ion concentration that propagates to distant organs, where defense responses are then induced."

Comment: It is not surprising that both plants and animals use the same signaling molecule.