The amino acid glycine has a well-established role in signalling in the mammalian central nervous system. For example, glycine acts synergistically with the major excitatory neurotransmitter, glutamate, to regulate the influx of ions such as calcium through N-methyl-D-aspartate (NMDA) receptors. Plants possess NMDA-like receptors, generically referred to as glutamate receptors (GLRs), named on the basis of their presumed ligand, glutamate. To date, glycine has not been implicated in plant GLR activity, or any other aspect of plant signalling. Dr. Campbell's group showed that glycine, and not glutamate, is likely to be the natural ligand for most plant GLR subunits, and that glutamate and glycine act synergistically to control ligand-mediated gating of calcium in plants. The Campbell lab also showed that glutamate and glycine synergism regulates hypocotyl elongation, a central component of light-responsive development. These novel findings uncover a hitherto unconsidered role for glycine signalling in plants, and show that the synergistic action of glutamate and glycine at NMDA-like receptors predates the divergence of plants and animals. The work provides compelling experimental evidence that rectifies previously published misconceptions related to the function of an important class of membrane receptors.

The Campbell lab's work on glycine signalling establishes a whole new area of signalling in plant biology, and provides evidence of a conserved mechanism of glycine perception whose establishment predates the evolutionary split between animals and plants. The work provides one of the few examples of the role of glycine signalling outside of the nervous system. The research shows how bioinformatics-derived structural hypotheses can be validated experimentally, to establish relationships between molecular structure and whole-organism biology. This work was recently published in The Plant Journal and was highlighted as a Feature Article (http://www.blackwellpublishing.com/journals/tpj/) selected by the journal editors "for the quality of science as well as potential broad appeal to [their] audience". The paper was also selected by Faculty of 1000 (http://www.facultyof1000.com/article/12969432) as "Exceptional", and received a rating of 9.0. Current work is aimed at testing hypotheses related to the role of glycine signalling in plants.

Personnel:

Dr. Christian Dubos

Publications (personnel supervised by Dr. Campbell are underlined):

Dubos C, Huggins D, Grant GH, Knight MR, Campbell MM (2003) A role for glycine in the gating of plant NMDA-like receptors. The Plant Journal 35: 800-810, doi: 10.1046/ j.1365-313X.2003.01849.x (BBSRC funded)