title: γ-Aminobutyric acid transaminase deficiency impairs central carbon metabolism and leads to cell wall defects during salt stress in Arabidopsis roots.
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.
authors.affiliation: IGEPP, UMR1349 INRA, Université de Rennes 1, F-35653, Le Rheu, France. hugues.renault@ibmp-cnrs.unistra.fr
authors.forename: Hugues
authors.initials: H
authors.lastname: Renault
authors.forename: Abdelhak
authors.initials: A
authors.lastname: El Amrani
authors.forename: Adeline
authors.initials: A
authors.lastname: Berger
authors.forename: Grégory
authors.initials: G
authors.lastname: Mouille
authors.forename: Ludivine
authors.initials: L
authors.lastname: Soubigou-Taconnat
authors.forename: Alain
authors.initials: A
authors.lastname: Bouchereau
authors.forename: Carole
authors.initials: C
authors.lastname: Deleu
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002473:Cell Wall / Q000201:enzymology* / Q000235:genetics; D055028:Comparative Genomic Hybridization; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D018698:Glutamic Acid / Q000378:metabolism; D018546:Hypocotyl / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D011073:Polyamines / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D019802:Succinic Acid / Q000378:metabolism; D000637:Transaminases / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D029681:Arabidopsis Proteins; D011073:Polyamines; D018698:Glutamic Acid; D012965:Sodium Chloride; D002244:Carbon; D019802:Succinic Acid; D000637:Transaminases; C489779:POP2 protein, Arabidopsis