title: Level of glutathione is regulated by ATP-dependent ligation of glutamate and cysteine through photosynthesis in Arabidopsis thaliana: mechanism of strong interaction of light intensity with flowering.
abstract: Glutathione (GSH) is associated with flowering in Arabidopsis thaliana, but how GSH biosynthesis is regulated to control the transition to flowering remains to be elucidated. Since the key reaction of GSH synthesis is catalyzed by gamma-glutamylcysteine synthetase (gamma-ECS) and all the gamma-ECS cDNAs examined contained extra sequences for plastid targeting, we investigated the relationships among GSH levels, photosynthesis and flowering. The GSH level in Arabidopsis increased with the light intensity. The ch1 mutants defective in a light-harvesting antenna in photosystem II showed reduced GSH levels with accumulation of the GSH precursor cysteine, and introduction of the gamma-ECS gene GSH1 under the control of the cauliflower mosaic virus 35S promoter (35S-GSH1) into the ch1 mutant altered the GSH level in response to the gamma-ECS mRNA level. These indicate that photosynthesis limits the gamma-ECS reaction to regulate GSH biosynthesis. Like the glutathione-biosynthesis-defective cad2-1 mutant, the ch1 mutants flowered late under weak-light conditions, and this late-flowering phenotype was rescued by supplementation of GSH. Introduction of the 35S-GSH1 construct into the ch1 mutant altered flowering in response to the gamma-ECS mRNA and GSH levels. These findings indicate that flowering in A. thaliana is regulated by the gamma-ECS reaction of GSH synthesis that is coupled with photosynthesis.
authors.affiliation: Research Institute for Biological Sciences, Okayama (RIBS Okayama), 7549-1 Yoshikawa, Okayama, 716-1241 Japan. ogawa_k@bc4.so-net.ne.jp
authors.forename: Ken'ichi
authors.initials: K
authors.lastname: Ogawa
authors.forename: Aya
authors.initials: A
authors.lastname: Hatano-Iwasaki
authors.forename: Mototsugu
authors.initials: M
authors.lastname: Yanagida
authors.forename: Masaki
authors.initials: M
authors.lastname: Iwabuchi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D003545:Cysteine / Q000378:metabolism; D035264:Flowers / Q000201:enzymology* / Q000254:growth & development / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D009154:Mutation / Q000235:genetics; D010775:Photic Stimulation; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione; D003545:Cysteine