Ozone-induced gene expression occurs via ethylene-dependent and -independent signalling

Plant Mol Biol. 2003 Mar;51(4):599-607. doi: 10.1023/a:1022385104386.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / genetics
  • Base Sequence
  • Cyclopropanes / pharmacology
  • Ethylenes / antagonists & inhibitors
  • Ethylenes / pharmacology*
  • Gene Expression Regulation, Plant / drug effects
  • Glucan 1,3-beta-Glucosidase
  • Glucuronidase / genetics
  • Glucuronidase / metabolism
  • Ozone / pharmacology*
  • Plant Proteins / genetics
  • Plants, Genetically Modified
  • Promoter Regions, Genetic / genetics
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Regulatory Sequences, Nucleic Acid / genetics
  • Signal Transduction / genetics*
  • Tobacco / drug effects
  • Tobacco / genetics
  • Tobacco / physiology
  • beta-Glucosidase / genetics

Substances

  • Cyclopropanes
  • Ethylenes
  • Plant Proteins
  • Recombinant Fusion Proteins
  • pathogenesis-related proteins, plant
  • Ozone
  • ethylene
  • Acyltransferases
  • stilbene synthase
  • beta-Glucosidase
  • Glucuronidase
  • Glucan 1,3-beta-Glucosidase
  • 1-methylcyclopropene