Shigeru Shigeoka

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Galactinol synthase (GolS) is a key enzyme in the synthesis of raffinose family oligosaccharides that function as osmoprotectants in plant cells. In leaves of Arabidopsis (Arabidopsis thaliana) plants overexpressing heat shock transcription factor A2 (HsfA2), the transcription of GolS1, -2, and -4 and raffinose synthase 2 (RS2) was highly induced; thus,(More)
Photosynthesis is a well-established source of reactive oxygen species (ROS) in plants. The photosynthetic electron transport chain (PET) operates in an aerobic environment; thus, regulatory systems are required to minimize ROS production. Moreover, an efficient antioxidant network is also essential in order to process ROS effectively and to maintain(More)
We isolated 76 high-light and heat-shock (HL + HS) stress-inducible genes, including a putative heat-shock transcription factor (HsfA2), by suppression-subtractive hybridization from Arabidopsis. The transcript level of HsfA2 was significantly increased under the several stress conditions or by the H(2)O(2) treatment. Furthermore, the induction of HsfA2(More)
Even under optimal conditions, many metabolic processes, including the chloroplastic, mitochondrial, and plasma membrane-linked electron transport systems of higher plants, produce active oxygen species (AOS). Furthermore, the imposition of biotic and abiotic stress conditions can give rise to excess concentrations of AOS, resulting in oxidative damage at(More)
Transgenic tobacco plants expressing a cyanobacterial fructose-1,6/sedoheptulose-1,7-bisphosphatase targeted to chloroplasts show enhanced photosynthetic efficiency and growth characteristics under atmospheric conditions (360 p.p.m. CO2). Compared with wild-type tobacco, final dry matter and photosynthetic CO2 fixation of the transgenic plants were 1.5-fold(More)
In Synechococcus PCC7942 cells grown in the dark, the concentrations of NAD(H) and NADP(H) were 128+/-2.5 and 483+/-4.0 microm, respectively, while those in the cells under light conditions were 100+/-5.0 and 649+/-7.0 microm, respectively. Analysis of gel filtration indicated that the change of the ratio of NADP(H) to NAD(H) in cyanobacterial cells under(More)
Nudix hydrolases are a family of proteins that catalyze the hydrolysis of a variety of nucleoside diphosphate derivatives. Twenty-four genes of the Nudix hydrolase homologues (AtNUDTs) with predicted localizations in the cytosol, chloroplasts, and mitochondria exist in Arabidopsis thaliana. Here, we demonstrated the comprehensive analysis of nine types of(More)
Ascorbate (AsA), the most abundant water-soluble redox compound in plants and eukaryotic algae, has multiple functions. There is compelling genetic evidence that the biosynthesis of AsA proceeds via a D-mannose/L-galactose pathway and is the most significant source of AsA in plants. AsA plays important roles in antioxidative defense, particularly via the(More)
The D-mannose/L-galactose pathway for the biosynthesis of vitamin C (L-ascorbic acid; AsA) has greatly improved the understanding of this indispensable compound in plants, where it plays multifunctional roles. However, it is yet to be proven whether the same pathway holds for all the different organs of plants, especially the fruit-bearing plants, at(More)
It has been known that leaves exposed to high light contain more L-ascorbic acid (AsA) than those in the shade. However, the mechanism of the light regulation of the AsA pool size in plants is largely unknown. In this work, the relationship between gene expression levels related to AsA biosynthesis and photosynthesis have been studied. When 2-week-old(More)