Distinct UV-B and UV-A/blue light signal transduction pathways induce chalcone synthase gene expression in Arabidopsis cells.
UV and blue light control the expression of flavonoid biosynthesis genes in a range of higher plants. To investigate the signal transduction processes involved in the induction of chalcone synthase (CHS) gene expression by UV-B and UV-A/blue light, we examined the effects of specific agonists and inhibitors of known signaling components in mammalian systems in a photomixotrophic Arabidopsis cell suspension culture. CHS expression is induced specifically by these wavelengths in the cell culture, in a manner similar to that in mature Arabidopsis leaf tissue. Both the UV-B and UV-A/blue phototransduction processes involve calcium, although the elevation of cytosolic calcium is insufficient on its own to stimulate CHS expression. The UV-A/blue light induction of CHS expression does not appear to involve calmodulin, whereas the UV-B response does; this difference indicates that the signal transduction pathways are, at least in part, distinct. We provide evidence that both pathways involve reversible protein phosphorylation and require protein synthesis. The UV-B and UV-A/blue light signaling pathways are therefore different from the phytochrome signal transduction pathway regulating CHS expression in other species.
Christie
J M
JM
Plant Molecular Science Group, Institute of Biomedical and Life Sciences, University of Glasgow, United Kingdom.
Jenkins
G I
GI
D000217:Acyltransferases / Q000235:genetics*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000528:radiation effects; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D017343:Genes, Plant / Q000528:radiation effects; D008027:Light; D010650:Phenylalanine Ammonia-Lyase / Q000235:genetics; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D010940:Plant Proteins / Q000378:metabolism; D047428:Protein Kinase Inhibitors; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000528:radiation effects; D014466:Ultraviolet Rays
D002147:Calmodulin; D004791:Enzyme Inhibitors; D010940:Plant Proteins; D047428:Protein Kinase Inhibitors; D011500:Protein Synthesis Inhibitors; D003513:Cycloheximide; D000217:Acyltransferases; C020141:flavanone synthetase; D010749:Phosphoprotein Phosphatases; D010650:Phenylalanine Ammonia-Lyase; D002118:Calcium