Poster: Reproductive Development
Abs #
476: Glutathione biosynthesis dependent on light harvesting in photosystem II positively regulates the transition to flowering in Arabidopsis thaliana
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Presenter: |
Ogawa, Ken'ichi , ogawa_k@bio-ribs.com |
Authors | Ogawa, Ken'ichi (A) (B) Hatano-Iwasaki, Aya (A) Iwabuchi, Masaki (A) | | Affiliations: |
(A): Research Institute for Biological Sciences Okayama (RIBS Okayama)
(B): Crest, JST
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Glutathione (GSH) is a redundant and ubiquitous tripeptide (g-glutamyl-cysteinyl glycine) that is synthesized in two reactions catalyzed via g-glutamylcysteine synthetase (g-ECS) and glutathione synthetase. It plays a role in cellular redox homeostasis, in particular, in adaptive responses to oxidative stresses. In addition, we have recently found that GSH is also associated with the growth and development of plants (1-3). However, the regulatory mechanisms associated with GSH remain to be elucidated. Since all the g-ECS cDNAs examined contained the extra sequences for plastide targeting, we here investigated the relationship between GSH biosynthesis and photosynthesis with reference to the transition to flowering. The levels of GSH in Arabidopsis plants increased with the light intensity. The chl mutants that are defective in a light-harvesting complex associated with photosystem II (PS II) showed low levels of GSH with the GSH precursor cysteine being accumulated. These indicate that light harvesting in PS II limits the rate of GSH biosynthesis. The chl mutants showed late flowering, in particular, under weak-light conditions. Other mutants defective in photosynthesis exhibited similar flowering phenotype. Supplementation of GSH to the growth medium or overexpression of g-ECS in the mutant restored the flowering phenotype. These indicate that the transition to flowering in A. thaliana is regulated by GSH that is synthesized via the reactions coupled with photosynthesis.
References: 1. Ogawa K, Iwabuchi M (2001) Plant Cell Physiol 42: 524; 2. Henmi K, Tsuboi S, Demura T, Fukuda H, Iwabuchi M, Ogawa K (2001) Plant Cell Physiol 42:673; 3. Ogawa K, Hatano-Iwasaki A, Yanagida M, Hemni K (2002) Flowering Newslett 34:45.
