Metabolic regulation of rice alpha-amylase and sucrose synthase genes in planta.
Isolated rice embryos were used to investigate the regulatory effects of endosperm extracts and pure sugars on the expression of alpha-amylase gene RAmy3D and a sucrose synthase gene homologous to the maize isozyme Ss2. The high-level expression of RAmy3D in the scutella of isolated embryos could be inhibited by a variety of sugars as well as endosperm extracts from germinated rice grains. Glucose, at a concentration of 250 mM, was most effective in repressing RAmy3D mRNA accumulation. Furthermore, this repression was reversible. Interestingly, RAmy3D repression was always accompanied by the induction of sucrose synthase gene expression. These results support a model in which the expression of alpha-amylase and sucrose synthase genes in the rice scutellum are counter-regulated by the influx of sugars from the endosperm.
Karrer
E E
EE
Department of Genetics, University of California at Davis 95616.
Rodriguez
R L
RL
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002241:Carbohydrates / Q000494:pharmacology*; D004331:Drosophila melanogaster / Q000235:genetics; D004794:Enzyme Repression; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D012275:Oryza / Q000201:enzymology* / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D012639:Seeds / Q000201:enzymology; D012689:Sequence Homology, Nucleic Acid; D003313:Zea mays / Q000201:enzymology / Q000235:genetics; D000516:alpha-Amylases / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification
D002241:Carbohydrates; D007527:Isoenzymes; D012333:RNA, Messenger; D005964:Glucosyltransferases; C022699:sucrose synthase; D000516:alpha-Amylases