Control of cell elongation and stress responses by steroid hormones and carbon catabolic repression in plants.
Molecular analysis of Arabidopsis mutants displaying hypocotyl elongation defects in both the dark and light revealed recently that steroids play an essential role as hormones in plants. Deficiencies in brassinosteroid biosynthesis and signalling permit photomorphogenic development and light-regulated gene expression in the dark, and result in severe dwarfism, male sterility and de-repression of stress-induced genes in the light. A cytochrome P450 steroid hydroxylase (CYP90) controls a rate limiting step in brassinosteroid biosynthesis and appears to function as a signalling factor in stress responses. Another key step in steroid biosynthesis is controlled by the Arabidopsis SNF1 kinases that phosphorylate the 3-hydroxy-3methylglutaryl-CoA reductase. The activity of SNF1 kinases is regulated by PRL1, an evolutionarily conserved alpha-importin-binding nuclear WD-protein. The prl1 mutation results in cell elongation defects, de-repression of numerous stress-induced genes, and augments the sensitivity of plants to glucose, cold stress and several hormones, including cytokinin, ethylene, auxin, and abscisic acid.
Salchert
K
K
Max-Planck Institut für Züchtungsforschung, Köln, Germany.
Bhalerao
R
R
Koncz-Kálmán
Z
Z
Koncz
C
C
D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins; D002244:Carbon / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects / Q000528:radiation effects; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D017343:Genes, Plant; D047908:Intracellular Signaling Peptides and Proteins; D008027:Light; D008954:Models, Biological; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction; D013250:Steroid Hydroxylases / Q000378:metabolism; D013256:Steroids / Q000378:metabolism
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; C492005:PRL1 protein, Arabidopsis; C115165:PRL1 protein, plant; D010940:Plant Proteins; D013256:Steroids; D002244:Carbon; D003577:Cytochrome P-450 Enzyme System; C113844:CPD protein, Arabidopsis; D013250:Steroid Hydroxylases; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases