title: An Arabidopsis mutant disrupted in ASN2 encoding asparagine synthetase 2 exhibits low salt stress tolerance.
abstract: Salt tolerance of Arabidopsis knockout mutant with T-DNA insertion in ASN2 gene encoding asparagine synthetase (AS, EC 6.3.5.4) (asn2-1) was investigated. Wild-type Arabidopsis Col0 and asn2-1 mutant were grown for one month by hydroponic culture and subjected to 100 mM NaCl stress for a short time from 6 to 24 h. The salt treatment decreased chlorophyll and soluble protein contents, and increased ammonium level in the asn2-1 leaves. The salinity induced ASN1 mRNA level in the wild-type and asn2-1 leaves. By contrast, the salt treatment inhibited the transcript and protein levels of chloroplastic glutamine synthetase 2 (GS2, EC 6.3.1.2) in the wild-type and asn2-1 leaves. Increase in asparagine and proline contents in response to the salt treatment provides evidence for the role of asparagine as a prevailing stress responding amino acid. Glutamate dehydrogenase (NADH-GDH, EC 1.4.1.2) exhibited a slight increase in the α-subunit and β-subunit in the wild-type line and the asn2-1 line, respectively under the salinity, whereas its in vitro aminating activity in the wild-type leaves was not affected. The results indicate that the asn2-1 mutant was impaired in nitrogen assimilation and translocation under salt treatment.
authors.affiliation: Unité de Recherche, Nutrition et Métabolisme Azotés et Protéines de Stress, 99 UR /09-20, Campus Universitaire, Faculté des Sciences de Tunis, Département de Biologie, Université Tunis EL MANAR, Tunis 1060, Tunisia.
authors.forename: Houda
authors.initials: H
authors.lastname: Maaroufi-Dguimi
authors.forename: Mohamed
authors.initials: M
authors.lastname: Debouba
authors.forename: Laure
authors.initials: L
authors.lastname: Gaufichon
authors.forename: Gilles
authors.initials: G
authors.lastname: Clément
authors.forename: Houda
authors.initials: H
authors.lastname: Gouia
authors.forename: Afef
authors.initials: A
authors.lastname: Hajjaji
authors.forename: Akira
authors.initials: A
authors.lastname: Suzuki
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001216:Asparagine / Q000378:metabolism*; D001217:Aspartate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D009584:Nitrogen / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011392:Proline / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D055049:Salt Tolerance / Q000235:genetics*; D012965:Sodium Chloride / Q000494:pharmacology; D012995:Solubility; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D021122:Protein Subunits; D000644:Quaternary Ammonium Compounds; D012333:RNA, Messenger; D002734:Chlorophyll; D012965:Sodium Chloride; D001216:Asparagine; D011392:Proline; D005969:Glutamate Dehydrogenase; C083818:glutamine synthetase 2; D001217:Aspartate-Ammonia Ligase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen