Dissection of the light signal transduction pathways regulating the two early light-induced protein genes in Arabidopsis.
The expression of light-regulated genes in plants is controlled by different classes of photoreceptors that act through a variety of signaling molecules. During photomorphogenesis, the early light-induced protein (Elip) genes are among the first to be induced. To understand the light signal transduction pathways that regulate Elip expression, the two Elip genes, Elip1 and Elip2, in Arabidopsis were studied, taking advantage of the genetic tools available for studying light signaling in Arabidopsis. Using two independent quantitative reverse transcriptase-PCR techniques, we found that red, far-red, and blue lights positively regulate expression of the Elip genes. Phytochrome A and phytochrome B are involved in this signaling. The cryptochrome or phototropin photoreceptors are not required for blue-light induction of either Elip gene, suggesting the involvement of an additional, unidentified, blue-light receptor. Although the COP9 signalosome, a downstream regulator, is involved in dark repression of both Elips, Elip1 and Elip2 show different expression patterns in the dark. The transcription factor HY5 promotes the light induction of Elip1, but not Elip2. A defect in photosystem II activity in greening of hy5 seedlings may result from the loss of Elip1. Heat shock positively controlled Elip1 and Elip2 in a light-independent fashion. This induction is independent of HY5, indicating that heat shock and light activate transcription of the Elip genes through independent pathways.
Harari-Steinberg
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Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Ohad
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Chamovitz
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D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D050976:Basic-Leucine Zipper Transcription Factors; D002734:Chlorophyll / Q000378:metabolism / Q000528:radiation effects; D056931:Cryptochromes; D004268:DNA-Binding Proteins; D003624:Darkness; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000378:metabolism / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D008027:Light; D045342:Light-Harvesting Protein Complexes; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D010786:Photoreceptor Cells; D017956:Photoreceptor Cells, Invertebrate; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010834:Phytochrome / Q000378:metabolism / Q000528:radiation effects; D051942:Phytochrome A; D051939:Phytochrome B; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction; D014157:Transcription Factors
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C401415:COP8 protein, Arabidopsis; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C078410:ELIP protein, Arabidopsis; D005136:Eye Proteins; D005420:Flavoproteins; C109254:HY5 protein, Arabidopsis; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D045342:Light-Harvesting Protein Complexes; D009687:Nuclear Proteins; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D051942:Phytochrome A; D010940:Plant Proteins; D043562:Receptors, G-Protein-Coupled; D014157:Transcription Factors; C119828:cry protein, Drosophila; D010834:Phytochrome; D051939:Phytochrome B; D002734:Chlorophyll