title: The negatively acting factors EID1 and SPA1 have distinct functions in phytochrome A-specific light signaling.
abstract: EID1 (empfindlicher im dunkelroten Licht) and SPA1 (suppressor of phytochrome A[phyA]-105) function as negatively acting components in phyA-specific light signaling. Mutants in the respective genes led to very similar phenotypes under weak-light conditions. To examine whether both genes are functionally redundant, detailed physiological and genetic analyses were performed with eid1 and spa1 mutants isolated from the same wild-type background. Measurements of hypocotyl elongation, anthocyanin accumulation, and Lhcb1-transcript accumulation under different light treatments demonstrated that SPA1 has a strong influence on the regulation of very low fluence responses and a weaker influence on high-irradiance responses. In contrast, EID1 severely altered high-irradiance responses and caused almost no change on very low fluence responses. Analyses on eid1 phyA-105 double mutants demonstrated that EID1 could not suppress the phenotype of the weak phyA allele under continuous far-red light. Measurements on eid1 spa1 double mutants exhibited a strong interference of both genes in the regulation of hypocotyl elongation. These results indicate that EID1 and SPA1 are involved in different but interacting phyA-dependent signal transduction chains.
authors.affiliation: Albert-Ludwigs-Universität Freiburg, Institut für Biologie 2/Botanik, Schänzlestrasse 1, D-79104 Freiburg, Germany.
authors.forename: Yong-Chun
authors.initials: YC
authors.lastname: Zhou
authors.forename: Monika
authors.initials: M
authors.lastname: Dieterle
authors.forename: Claudia
authors.initials: C
authors.lastname: Büche
authors.forename: Thomas
authors.initials: T
authors.lastname: Kretsch
mesh_terms: D000483:Alleles; D000872:Anthocyanins / Q000378:metabolism / Q000528:radiation effects; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D018797:Cell Cycle Proteins / Q000502:physiology*; D002734:Chlorophyll / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins / Q000502:physiology*; D044783:F-Box Proteins; D018546:Hypocotyl / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes; D009154:Mutation; D009687:Nuclear Proteins / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D045332:Photosystem II Protein Complex; D010834:Phytochrome / Q000378:metabolism*; D051942:Phytochrome A; D010940:Plant Proteins; D015398:Signal Transduction / Q000528:radiation effects
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; C490217:CAB1 protein, Arabidopsis; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C426104:EID1 protein, Arabidopsis; D044783:F-Box Proteins; D045342:Light-Harvesting Protein Complexes; D009687:Nuclear Proteins; C497973:PHYA protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D051942:Phytochrome A; D010940:Plant Proteins; C118571:SPA1 protein, Arabidopsis; D010834:Phytochrome; D002734:Chlorophyll