US EPA

7442297 

Journal Article 

Arabidopsis mutants resistant to S(+)-beta-methyl-alpha, beta-diaminopropionic acid, a cycad-derived glutamate receptor agonist 

Brenner, ED; Martinez-Barboza, N; Clark, AP; Liang, QS; Stevenson, DW; Coruzzi, GM 

2000 

1 

Plant Physiology
ISSN: 0032-0889
EISSN: 1532-2548 

124 

4 

1615-1624 

English 

11115879 

10.1104/pp.124.4.1615 

WOS:000165982500026 

Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that are the predominant neuroreceptors in the mammalian brain. Genes with high sequence similarity to animal iGluRs have been identified in Arabidopsis. To understand the role of Arabidopsis glutamate receptor-like (AtGLR) genes in plants, we have taken a pharmacological approach by examining the effects of BMAA [S(+)-beta-methyl-alpha, beta-diaminopropionic acid], a cycad-derived iGluR agonist, on Arabidopsis morphogenesis. When applied to Arabidopsis seedlings, BMAA caused a 2- to 3-fold increase in hypocotyl elongation and inhibited cotyledon opening during early seedling development. The effect of BMAA on hypocotyl elongation is light specific. Furthermore, BMAA effects on early morphogenesis of Arabidopsis can be reversed by the simultaneous application of glutamate, the native iGluR agonist in animals. To determine the targets of BMAA action in Arabidopsis, a genetic screen was devised to isolate Arabidopsis mutants with a BMAA insensitive morphology (bim). When grown in the light on BMAA, bim mutants exhibited short hypocotyls compared with wild type. bim mutants were grouped into three classes based on their morphology when grown in the dark in the absence of BMAA. Class-I bim mutants have a normal, etiolated morphology, similar to wild-type plants. Class-II bim mutants have shorter hypocotyls and closed cotyledons when grown in the dark. Class-III bim mutants have short hypocotyls and open cotyledons when grown in the dark, resembling the previously characterized constitutively photomorphogenic mutants (cop, det, fus, and shy). Further analysis of the bim mutants should help define whether plant-derived iGluR agonists target glutamate receptor signaling pathways in plants. 

BMAA; etiolation; glutamate receptor agonist; glutamate receptor; ion channel; mutant; physical resistance; plant growth; plant morphology; seedling; signal transduction; wild relative; Amino Acids, Diamino; Arabidopsis; Cotyledon; Dose-Response Relationship, Drug; Excitatory Amino Acid Agonists; Hypocotyl; Light; Morphogenesis; Mutagenesis; Mutation; Phenotype; Plants; Animalia; Arabidopsis; Cycas; Embryophyta; Mammalia