Effects of (+)-8',8',8'-trifluoroabscisic acid on alpha-amylase expression and sugar accumulation in rice cells.
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.
Kashem
M A
MA
Laboratory of Molecular Life Sciences, Graduate School of Science and Technology, Niigata University, Japan.
Hori
H
H
Itoh
K
K
Hayakawa
T
T
Todoroki
Y
Y
Hirai
N
N
Ohigashi
H
H
Mitsui
T
T
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*
D005875:Gibberellins; D010937:Plant Growth Regulators; C107205:8',8',8'-trifluoroabscisic acid; D000040:Abscisic Acid; C007842:gibberellic acid; D000516:alpha-Amylases