Ozone-induced gene expression occurs via ethylene-dependent and -independent signalling.
Recent studies suggest that ethylene is involved in signalling ozone-induced gene expression. We show here that application of ozone increased glucuronidase (GUS) expression of chimeric reporter genes regulated by the promoters of the tobacco class I beta-1,3-glucanases (GLB and Gln2) and the grapevine resveratrol synthase (Vst1) genes in transgenic tobacco leaves. 5'-deletion analysis of the class I beta-1,3-glucanase promoter revealed that ozone-induced gene regulation is mainly mediated by the distal enhancer region containing the positively acting ethylene-responsive element (ERE). In addition, application of 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, blocked ozone-induced class I beta-1,3-glucanase promoter activity. Enhancer activity and ethylene-responsiveness depended on the integrity of the GCC boxes, cis-acting elements present in the ERE of the class I beta-1,3-glucanase and the basic-type pathogenesis-related PR-1 protein (PRB-1b) gene promoters. The minimal PRB-1b promoter containing only the ERE with intact GCC boxes, was sufficient to confer 10-fold ozone inducibility to a GUS-reporter gene, while a substitution mutation in the GCC box abolished ozone responsiveness. The ERE region of the class I beta-1,3-glucanase promoter containing two intact GCC boxes confered strong ozone inducibility to a minimal cauliflower mosaic virus (CaMV) 35S RNA promoter, whereas two single-base substitution in the GCC boxes resulted in a complete loss of ozone inducibility. Taken together, these datastrongly suggest that ethylene is signalling ozone-induced expression of class I beta-l,3-glucanase and PRB-1b genes. Promoter analysis of the stilbene synthase Vst1 gene unravelled different regions for ozone and ethylene-responsiveness. Application of 1-MCP blocked ethylene-induced Vst1 induction, but ozone induction was not affected. This shows that ozone-induced gene expression occurs via at least two different signalling mechanisms and suggests an additional ethylene independent signalling pathway for ozone-induced expression of genes involved in phytoalexin biosynthesis.
Grimmig
Bernhard
B
GSF-National Research Center for Environment and Health, Institute of Biochemical Plant Pathology, 85764 Neuherberg, Germany.
Gonzalez-Perez
Maria N
MN
Leubner-Metzger
Gerhard
G
Vögeli-Lange
Regina
R
Meins
Fred
F
Hain
Rüdiger
R
Penuelas
Josep
J
Heidenreich
Bernd
B
Langebartels
Christian
C
Ernst
Dieter
D
Sandermann
Heinrich
H
D000217:Acyltransferases / Q000235:genetics; D001483:Base Sequence; D003521:Cyclopropanes / Q000494:pharmacology; D005030:Ethylenes / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D043326:Glucan 1,3-beta-Glucosidase; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D010126:Ozone / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics*; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D001617:beta-Glucosidase / Q000235:genetics
D003521:Cyclopropanes; D005030:Ethylenes; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; C053376:pathogenesis-related proteins, plant; D010126:Ozone; C036216:ethylene; D000217:Acyltransferases; C022674:stilbene synthase; D001617:beta-Glucosidase; D005966:Glucuronidase; D043326:Glucan 1,3-beta-Glucosidase; C412563:1-methylcyclopropene