The putative glutamate receptor 1.1 (AtGLR1.1) in Arabidopsis thaliana Regulates Abscisic Acid Biosynthesis and Signaling to Control Development and Water Loss

Abstract

;The involvement of the putative glutamate receptor 1.1 (AtGLR1.1) gene in the regulation of abscisic acid (ABA) biosynthesis and signaling was investigated in Arabidopsis. Seeds from AtGLR1.1-deficient (antiAtGLR1.1) lines had increased sensitivity to exogenous ABA with regard to the effect of the hormone on the inhibition of seed germination and root growth. Seed germination, which was inhibited by an animal ionotropic glutamate receptor antagonist, 6,7-dinitroquinoxaline-2,3-[1H,4H]-dione, was restored by coincubation with an inhibitor of ABA biosynthesis, fluridone. These results confirm that germination in antiAtGLR1.1 lines was inhibited by increased ABA. When antiAtGLR1.1 and WT seeds were co-incubated in fluridone and exogenous ABA, the antiAtGLR1.1 seeds were more sensitive to ABA. In addition, the antiAtGLR1.1 lines exhibited altered expression of ABA biosynthetic (ABA) and signaling (ABI) genes, when compared with WT. Combining the physiological and molecular results suggest that ABA biosynthesis and signaling in antiAtGLR1.1 lines are altered. ABA levels in leaves of antiAtGLR1.1 lines are higher than those in WT. In addition, the antiAtGLR1.1 lines had reduced stomatal apertures, and exhibited enhanced drought tolerance due to deceased water loss compared with WT lines. The results from these experiments imply that ABA biosynthesis and signaling can be regulated through AtGLR1.1 to trigger pre-and post-germination arrest and changes in whole plant responses to water stress. Combined with our earlier results, these findings suggest that AtGLR1.1 integrates and regulates the different aspects of C, N and water balance that are required for normal plant growth and development.

Interacting Glutamate Receptor-Like Proteins in Phloem Regulate Lateral Root Initiation in Arabidopsis

“…In the years since GLUTAMATE RECEPTOR-LIKE (GLR) genes were discovered in plants (Lam et al, 1998;Lacombe et al, 2001), research has focused on their phylogeny and evolution (Chiu et al, 1999(Chiu et al, , 2002Turano et al, 2001), expression patterns and transcriptional responses (Meyerhoff et al, 2005;Roy et al, 2008), roles in carbon:nitrogen balance (Kang and Turano, 2003), abscisic acid sensing (Kang et al, 2004), and contributions to ionic relations, including Ca 2+ signaling (Kim et al, 2001;Qi et al, 2006;Stephens et al, 2008;Cho et al, 2009). The last category relates closely to the presumed molecular function of GLRs because the homologous ionotropic Glu receptors (iGluRs) in animals combine as heterotetramers to form amino acid-gated ion channels with varying permeability to Na + , K + , and Ca 2+ (Traynelis et al, 2010).…”

Inter-subunit interactions between Glutamate-Like Receptors inArabidopsis

“…16 The predicted membrane topology and orientation of the protein as a tetramer, with the ATD and LBD exposed to the external side of the membrane, are considered to be conserved in plant GLRs. 17 Understanding the function of plant GLRs has previously been hampered by gene redundancy and toxicity although genetic, pharmacological, and electrophysiological approaches suggested diverse physiological roles such as carbon/nitrogen balance regulation, 18,19 stomatal opening, 20 pollen tube growth, 21 plant-pathogen interaction, [22][23][24] responses to wound, 25,26 and lateral root formation. 12 Recently, 2 of the Arabidopsis GLRs, AtGLR3.4 and 1.4, were shown to function as amino acid gated channels when expressed in heterologous systems, 13,27 further confirming the functional commonality of plant and mammalian glutamate receptors.…”

N-Acylethanolamine Metabolism Interacts with Abscisic Acid Signaling inArabidopsis thalianaSeedlings

“…In fact, NAE12:0 was used by several groups to inhibit PLD-a-mediated processes in vivo (Austin-Brown and Chapman, 2002;Dhonukshe et al, 2003;Motes et al, 2005;Komis et al, 2006). In addition, NAE in mammals and ABA in plants also have been shown to exert their effects on various physiological processes through calcium and potassium channels, reactive oxygen species, nitric oxide release, Glu receptors, and sphingolipids (Coursol et al, 2003;Kang et al, 2004;Bright et al, 2006;Chai et al, 2006).…”