title: The synergistic effects of sugar and abscisic acid on myo-inositol-1-phosphate synthase expression.
abstract: 1L-myo-inositol-1-phosphate [Ins(1)P1] synthase (EC 5.5.1.4) catalyses the formation of Ins(1)P1 from glucose-6-phosphate, the first step in the biosynthesis of myo-inositol. Ins(1)P1 is a precursor of phytin (inositol hexakisphosphate), a storage form of phosphate and cations in seeds. Since sucrose and abscisic acid (ABA) are known to affect synthesis of storage compounds in seeds, we investigated the effects of ABA and sucrose on Ins(1)P1 synthase gene (RINO1) expression in cultured cells derived from the scutellum of mature rice seeds. Higher levels of RINO1 transcript accumulation were evident after treatment with either sucrose (10-100 mM) or ABA (10-8 M to 10-4 M). Glucose was also effective in the upregulation, whereas mannitol was not, suggesting that sucrose and glucose acted as metabolizable sugars and not as osmotica. Treatment with ABA and sucrose together resulted in much higher levels of transcript accumulation, suggesting a synergistic induction of the Ins(1)P1 synthase gene.
authors.affiliation: aGraduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan bGraduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
authors.forename: Kaoru T
authors.initials: KT
authors.lastname: Yoshida
authors.forename: Toru
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Satoshi
authors.initials: S
authors.lastname: Naito