May 3 (UPI) -- Researchers have identified a new type of communication between plant cells.
Plants don't have a central nervous system, but to communicate, their cells rely on proteins that look a lot like the glutamate receptors used by the neuronal cells of animals. Plants used these proteins to orchestrate mating, dictate growth patterns and trigger defense mechanisms.
In a new study, published this week in the journal Science, researchers present a new model to describe how glutamate receptor-like proteins, or GLR proteins, function in plant cells.
Scientists watched the protein's behavior inside the pollen cells of thale cress, Arabidopsis thaliana, a weed often used as a research model. Their observations suggest "cornichon" proteins help ferry GLRs from place to place and regulate the protein's activity in each cell.
With the help of cornichon proteins, GLRs work to control the concentration and flow of calcium ions in plant cells.
"Calcium concentration is one of the most important parameters inside all cells. It is so well regulated that it allows cells to encode information," José Feijó, a professor of cell biology and molecular genetics at the University of Maryland, said in a news release. "Put another way, calcium is the lingua franca of cell communication."
Calcium ions are also essential to neuronal function in animals.
"Our results suggest that GLRs play a role in this basic communication system in plants, and we also propose a mechanism for how the system works in plant cells," Feijó said.
Unlike glutamate receptors in animals, which are found on the outside of cells, GLRs are most common on structures inside the walls of plant cells. What's more, glutamate is much more important to neuronal function in animals than it is to communication among plant cells.
But the research is interesting in that it points to the common ancestor shared by plants and animals, a single-celled organism that lived millions of years ago. The ancestor may have bequeathed both lineages with similar biochemical communication tools.
The communication mechanisms deployed by plants aren't a more primitive version of animal neurons, however, as they boast their own unique communication systems.
"Our results support the idea that individual plant cells have a level of autonomy that animal cells do not," Feijó said. "Each plant cell has its own immune system, for example. And they have more communication channels to deal with the fact that they are stuck in place. Every flowering plant has more GLRs than animals have glutamate receptors. Our proposed model for plant cell communication suggests one reason for this abundance of GLRs."
Scientists believe their new plant communication model could help researchers study crop disease and better understand how plants respond to climate change and other stressors. Feijó thinks it could even help scientists analyze the mutations that plague glutamate receptor genes in humans, the source of neurodegenerative disease.