title: Light has a specific role in modulating Arabidopsis gene expression at low temperature.
abstract: BACKGROUND
  Light and temperature are the key abiotic modulators of plant gene expression. In the present work the effect of light under low temperature treatment was analyzed by using microarrays. Specific attention was paid to the up and down regulated genes by using promoter analysis. This approach revealed putative regulatory networks of transcription factors behind the induction or repression of the genes.
  
  
  RESULTS
  Induction of a few oxidative stress related genes occurred only under the Cold/Light treatment including genes encoding iron superoxide dismutase (FeSOD) and glutathione-dependent hydrogen peroxide peroxidases (GPX). The ascorbate dependent water-water cycle genes showed no response to Cold/Light or Cold/Dark treatments. Cold/Light specifically induced genes encoding protective molecules like phenylpropanoids and photosynthesis-related carotenoids also involved in the biosynthesis of hormone abscisic acid (ABA) crucial for cold acclimation. The enhanced/repressed transcript levels were not always reflected on the respective protein levels as demonstrated by dehydrin proteins.
  
  
  CONCLUSIONS
  Cold/Light up regulated twice as many genes as the Cold/Dark treatment and only the combination of light and low temperature enhanced the expression of several genes earlier described as cold-responsive genes. Cold/Light-induced genes included both cold-responsive transcription factors and several novel ones containing zinc-finger, MYB, NAC and AP2 domains. These are likely to function in concert in enhancing gene expression. Similar response elements were found in the promoter regions of both the transcription factors and their target genes implying a possible parallel regulation or amplification of the environmental signals according to the metabolic/redox state in the cells.
authors.affiliation: University of Turku, Department of Biology, Plant Physiology and Molecular Biology, Tykistokatu 6, BioCity A, 6th floor, FIN-20520 Turku, Finland. artsoi@utu.fi
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Soitamo
authors.forename: Mirva
authors.initials: M
authors.lastname: Piippo
authors.forename: Yagut
authors.initials: Y
authors.lastname: Allahverdiyeva
authors.forename: Natalia
authors.initials: N
authors.lastname: Battchikova
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
mesh_terms: D000064:Acclimatization; D017360:Arabidopsis / Q000235:genetics* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003080:Cold Temperature; D003624:Darkness; D015536:Down-Regulation / Q000502:physiology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D008027:Light; D020411:Oligonucleotide Array Sequence Analysis; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000235:genetics; D018515:Plant Leaves; D011485:Protein Binding; D020218:Response Elements; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D045332:Photosystem II Protein Complex; D014157:Transcription Factors