title: Effects of (+)-8',8',8'-trifluoroabscisic acid on alpha-amylase expression and sugar accumulation in rice cells.
abstract: The effects of (+)-8',8',8'-trifluoroabscisic acid (trifluoro-ABA) on alpha-amylase expression were studied in rice embryoless half-seeds, scutella, and suspension-cultured cells derived from the embryo, and the effects of the analog on sugar accumulation were also studied in scutella and suspension-cultured cells. Treatment with (+)-trifluoro-ABA strongly inhibited the gibberellic acid-inducible expression of alpha-amylase I-1 encoded by RAmy1A in the aleurone layers of embryoless half-seeds at the levels of transcription, protein synthesis, and enzyme activity. It was also found that (+)-trifluoro-ABA stimulated (i) the uptake of glucose from the incubation medium and (ii) the synthesis of sucrose in scutellar tissues and suspension-cultured cells of rice. The biological activity of (+)-trifluoro-ABA was found to be more potent and persistent than that of natural ABA. We further examined the effects of trifluoro-ABA on the expression of alpha-amylase I-1 in scutellar tissues and suspension-cultured cells. It was found that (+)-trifluoro-ABA did not inhibit the formation of alpha-amylase I-1 in the absence of external glucose. However, glucose and (+)-trifluoro-ABA cooperatively suppressed the formation of alpha-amylase I-1. Judging from these results, we conclude that the regulatory mechanism for the expression of alpha-amylase I-1 in the scutellar epithelium is distinguishable from that operating in the aleurone layer.
authors.affiliation: Laboratory of Molecular Life Sciences, Graduate School of Science and Technology, Niigata University, Japan.
authors.forename: M A
authors.initials: MA
authors.lastname: Kashem
authors.forename: H
authors.initials: H
authors.lastname: Hori
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Y
authors.initials: Y
authors.lastname: Todoroki
authors.forename: N
authors.initials: N
authors.lastname: Hirai
authors.forename: H
authors.initials: H
authors.lastname: Ohigashi
authors.forename: T
authors.initials: T
authors.lastname: Mitsui
mesh_terms: D000040:Abscisic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D050260:Carbohydrate Metabolism; D002478:Cells, Cultured; D018525:Germination; D005875:Gibberellins / Q000494:pharmacology; D012275:Oryza / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010937:Plant Growth Regulators / Q000494:pharmacology; D012639:Seeds / Q000378:metabolism / Q000502:physiology; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D005875:Gibberellins; D010937:Plant Growth Regulators; C107205:8',8',8'-trifluoroabscisic acid; D000040:Abscisic Acid; C007842:gibberellic acid; D000516:alpha-Amylases