Receptors for Neuron Communication in Humans Vital for Reproduction in Mosses

College of Computer, Mathematical, and Natural Sciences

Study shows plant version of human glutamate receptor helps moss sperm find eggs, controls spore developmentGlutamate receptors play a central role in the human nervous system. Scientists estimate 90 percent of the human brain’s synapses, or connections between neurons, send signals using glutamate. The role of similar receptors in plants, which do not have a nervous system, is not fully understood.
A new study led by José Feijó, professor of cell biology and molecular genetics at the University of Maryland, revealed two previously unknown roles for glutamate receptor-like proteins in plants: controlling the navigation of sperm to locate eggs and regulating the development of fertilized eggs. This work was published in the journal Nature on July 24, 2017. 
“Scientists have shown that plants’ glutamate receptor-like proteins play a role in pollen tube growth and defense against pathogens, but we discovered completely novel functionalities for these receptors that no one has ever observed before,” Feijó said. “Since glutamate receptors were thought to act in neural transmission and essentially nothing else, no one knows why plants would have so many copies of these genes. It is very exciting to find that such genes may have been conserved during plant evolution to mediate cell-to-cell communication in sexual reproduction.”
Feijó and his collaborators tested the function of glutamate receptor-like proteins in the moss Physcomitrella patens because it contains only two genes that encode for these proteins. The popular plant model Arabidopsis thaliana, on the other hand, contains 20 glutamate receptor-like genes.
After the researchers removed the two glutamate receptor-like genes from P. patens by mutation, the mosses grew normally, but did not reproduce. The reason: the mutant plants’ sperm did not reach the archegonia, the female organ that contains eggs for fertilization and secretes a chemical signal to attract sperm.
While normal sperm twisted and tumbled and took sharp turns to find the archegonia entrance, mutant sperm ...

Read More