title: Regulation of isoprene synthase promoter by environmental and internal factors.
abstract: Isoprene synthase (ISPS) catalyzes the formation of isoprene, an important volatile terpenoid with strong effects on global atmospheric chemistry and protective physiological functions in plant leaves. Many terpene synthase genes including isoprene synthase, a member of the TPS-b cluster of this numerous gene family, were already functionally analysed but much less is known about regulation of their promoters. To study regulation of the PcISPS gene in detail we developed transgenic Grey poplar (Populus x canescens) and Arabidopsis thaliana plants in which the PcISPS promoter is fused to enhanced green fluorescent protein (E-GFP) and beta-glucuronidase (GUS) reporter genes. We analysed these reporters during plant development, for organ specificity and in plants subjected to different light and temperature regimes. We observed low promoter activity in non-isoprene emitting tissue like roots where ISPS gene is transcribed but no active enzyme is detectable. In leaves we demonstrate that light and temperature directly modulate ISPS promoter activity. Moreover, with confocal laser scanning microscopy we show a cell specific gradient of ISPS promoter activity within the leaf parenchyma depending on light direction. Our results indicate that ISPS promoter activity, which correlates with basal isoprene emission capacity, is not uniformly distributed within leaf tissue and that it can adapt rapidly towards internal as well as external environmental stimuli.
authors.affiliation: Institute for Meteorology and Climate Research, Kreuzeckbahnstrasse 19, 82467, Garmisch-Partenkirchen, Germany.
authors.forename: Gyöngyi
authors.initials: G
authors.lastname: Cinege
authors.forename: Sandrine
authors.initials: S
authors.lastname: Louis
authors.forename: Robert
authors.initials: R
authors.lastname: Hänsch
authors.forename: Jörg-Peter
authors.initials: JP
authors.lastname: Schnitzler
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics*; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects; D002070:Butadienes / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D004777:Environment; D005453:Fluorescence; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D005966:Glucuronidase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D045782:Hemiterpenes / Q000378:metabolism; D008027:Light; D009928:Organ Specificity / Q000528:radiation effects; D010420:Pentanes / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects; D032107:Populus / Q000166:cytology / Q000201:enzymology* / Q000235:genetics* / Q000528:radiation effects; D011401:Promoter Regions, Genetic / Q000235:genetics*; D013696:Temperature
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; D002734:Chlorophyll; D049452:Green Fluorescent Proteins; D019883:Alkyl and Aryl Transferases; C093854:isoprene synthase; D005966:Glucuronidase