A new study published in the journal Nature Communications has shown that, despite not having a nervous system, plants send signals normally associated with animals when they encounter stress.
Rosa californica in Irvine, CA. Image credit: Wintertanager J.T. Storey / CC BY-SA 3.0.
“We’ve known for a long-time that the animal neurotransmitter GABA (gamma-aminobutyric acid) is produced by plants under stress, for example when they encounter drought, salinity, viruses, acidic soils or extreme temperatures,” said Dr Matthew Gilliham from the University of Adelaide, Australia, who is the senior author on the study.
“But it was not known whether GABA was a signal in plants. We’ve discovered that plants bind GABA in a similar way to animals, resulting in electrical signals that ultimately regulate plant growth when a plant is exposed to a stressful environment.”
By identifying how plants respond to GABA Dr Gilliham and co-authors are optimistic that they have opened up many new possibilities for modifying how plants respond to stress.
“The major stresses agricultural crops face like pathogens and poor environmental conditions account for most yield losses around the planet – and consequently food shortages. By identifying how plants use GABA as a stress signal we have a new tool to help in the global effort to breed more stress resilient crops to fight food insecurity,” said co-lead author Prof Stephen Tyerman, also from the University of Adelaide.
Despite a similar function, the proteins that bind GABA and their mammalian counterparts only resemble each other in the region where they interact with the neurotransmitter – the rest of the protein looks quite different.
“This raises very interesting questions about how GABA has been recruited as a messenger in both plant and animal kingdoms. It seems likely that this has evolved in both kingdoms separately,” said study lead author Dr Sunita Ramesh from the University of Adelaide.
The findings could also explain why particular plant-derived drugs used as sedatives and anti-epileptics work in humans.
These drugs are able to interact with proteins in the GABA-signaling system in both plants and animals – suggesting that future work on other plant GABA signaling agents will also benefit the medical field.
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Sunita A. Ramesh et al. 2015. GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters. Nature Communications 6, article number: 7879; doi: 10.1038/ncomms8879
