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Plant Cell Environ. 2013 May;36(5):1009-18. doi: 10.1111/pce.12033. Epub 2012 Nov 29.

γ-Aminobutyric acid transaminase deficiency impairs central carbon metabolism and leads to cell wall defects during salt stress in Arabidopsis roots.

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1
IGEPP, UMR1349 INRA, Université de Rennes 1, F-35653, Le Rheu, France. hugues.renault@ibmp-cnrs.unistra.fr

Abstract

Environmental constraints challenge cell homeostasis and thus require a tight regulation of metabolic activity. We have previously reported that the γ-aminobutyric acid (GABA) metabolism is crucial for Arabidopsis salt tolerance as revealed by the NaCl hypersensitivity of the GABA transaminase (GABA-T, At3g22200) gaba-t/pop2-1 mutant. In this study, we demonstrate that GABA-T deficiency during salt stress causes root and hypocotyl developmental defects and alterations of cell wall composition. A comparative genome-wide transcriptional analysis revealed that expression levels of genes involved in carbon metabolism, particularly sucrose and starch catabolism, were found to increase upon the loss of GABA-T function under salt stress conditions. Consistent with the altered mutant cell wall composition, a number of cell wall-related genes were also found differentially expressed. A targeted quantitative analysis of primary metabolites revealed that glutamate (GABA precursor) accumulated while succinate (the final product of GABA metabolism) significantly decreased in mutant roots after 1 d of NaCl treatment. Furthermore, sugar concentration was twofold reduced in gaba-t/pop2-1 mutant roots compared with wild type. Together, our results provide strong evidence that GABA metabolism is a major route for succinate production in roots and identify GABA as a major player of central carbon adjustment during salt stress.

PMID:
23148892
DOI:
10.1111/pce.12033
[Indexed for MEDLINE]
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