title: Regulation of alpha-galactosidase gene expression in primary foliage leaves of barley ( Hordeum vulgare L) during dark-induced senescence.
abstract: alpha-Galactosidase activity (alpha- d-galactoside galactohydrolase, EC 3.2.1.22) increased during dark-induced senescence in primary foliage leaves of barley ( Hordeum vulgare L. cv. Steffi). The changes in activity were accompanied by parallel changes in expression of the HvSF11 gene encoding a putative alpha-galactosidase. The transcript level of HvSF23 encoding a second putative alpha-galactosidase stayed constant during leaf senescence. Both alpha-galactosidase activity and the level of the HvSF11 transcript decreased after exogenous application of sucrose and glucose to detached dark-incubated leaves. In contrast, the HvSF23 transcript level was not influenced by sugars. Application of glucose analogs to detached and dark-incubated leaves revealed that phosphorylation of hexose by hexokinase modulates both the alpha-galactosidase activity and the expression of HvSF11. These results indicate that the expression of the genes coding for two alpha-galactosidase isoenzymes is regulated by different signalling pathways, suggesting different functions for the two gene products.
authors.affiliation: Institute of Botany, University of Kiel, Olshausenstrasse 40, 24098 Kiel, Germany. bchrost@bot.uni-kiel.de
authors.forename: Bozena
authors.initials: B
authors.lastname: Chrost
authors.forename: Annekatrin
authors.initials: A
authors.lastname: Daniel
authors.forename: Karin
authors.initials: K
authors.lastname: Krupinska
mesh_terms: D003624:Darkness; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D005947:Glucose / Q000494:pharmacology; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D013395:Sucrose / Q000494:pharmacology; D000519:alpha-Galactosidase / Q000235:genetics* / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D013395:Sucrose; D000519:alpha-Galactosidase; D005947:Glucose