Analysis of glutamate receptor genes in plants: Progress and prospects

Glutamate receptor-like genes (GLR) have been described in a number of plant species including Arabidopsis thaliana (Lam etal., 1998; Kim etal., 2001; Lacombe etaL, 2001) and Brassica napus (Genbank accession number AF109392). These GLR genes have similarity in primary sequence and domain organization to ionotropic glutamate receptors (iGluRs) in animals. At the moment, plant genes that have sequence similarity to the other major animal glutamate receptor gene family, metabotropic glutamate receptor, have not been found. However, a study by Turano et aL (2001) suggests an evolutionary link between Arabidopsis glutamate receptor genes (AtGLRs) and seven transmembrane G-protein-linked receptors, which includes GAB A receptors as well as metabotropic glutamate receptors, based on primary sequence similarity in the N-terminus of the proteins. Like animals, plants appear to have multiple GLR genes, and 20 genes have been uncovered in the complete Arabidopsis genome. In this chapter, we will focus on works that examine the glutamate receptor gene family from Arabidopsis (AtGLR), including forward and reverse genetic approaches and other studies that aim to determine the in vivo function of GLRs in plants.