Characterization of eid3 and the putative rei mutants : new insights on Phytochrome A signaling

To identify highly specific components of phytochrome A (PhyA) signaling, a new screening program (SP) was performed. This SP consists of repetitive pulse treatment of 20 minutes red light followed by 20 minutes far-red light. This multiple pulse program was applied to isolate mutants which were either impaired in light dependent PhyA degradation or exhibited an increased light sensitiveness. The eid (empfindlicher im dunkelroten Licht) mutants were isolated from pools of phyB-5 (Ler) seedlings mutagenised with ethyl methansulfat – EMS (Büche et al., 2000). <br>The eid3 is a dominant mutant which maps on top of chromosome I. To compare the light sensitivity between eid3 mutant and the wild type, fluence rate response curves analysis for hypocotyl elongation and anthocyanin accumulation were determined. Under far-red light conditions both responses were affected which are typical high irradiance responses (HIR). In regard to hypocotyl elongation, the sensitivity was increased by one order of magnitude and also the anthocyanin accumulation was significally hyperstimulated in the eid3 mutant. Under red light conditions the photoinhibition of hypocotyl growth was hypersensitive to very low fluence rates. In contrast to the wild type the eid3 mutant accumulated anthocyanin in red light. In addition, the action spectra for HIR of eid3 was shifted to red light wavelengths. One explanation to the observed hypersensitivity may be an overexpression or a reduction of PhyA. However, the eid3 mutant did not show alteration in the degradation kinetic and levels of PhyA. Moreover, phyA is epistatic over eid3 therefore the pleiotropic effects of eid3 mutants were dependent on PhyA. <br>The eid1 mutant was also isolated under this SP condition. The EID1 gene codify for a F-box protein which is member of SCF - E3 ubiquitin ligase – complex. The SCFEID1 complex regulates the PhyA signal without impairing the photoreceptor levels (Dieterle et al., 2001). So far, the substrate which is recognized by the SCFEID1 complex remains unknown. On the attempt to identify the SCFEID1 complex substrate and the components of the SCFEID1 pathway a suppressor screening for the revertants of eid1-3 mutant was performed. The preliminary phenotypical and genetical characterization of the putative rei (revertants of eid1-3 mutant) lines, presented on this work, presumed that the aim of this approach will be in further investigation accomplished.

Author dc:creator

• Piñas-Fernández, Aurora

Contributors dc:contributor

• Schäfer, Eberhard

• Arabidopsis
• Mutanten
• Phytochrome
• Mutants

Repository record source_url

https://freidok.uni-freiburg.de/data/1174

OAI identifier oai:identifier

oai:freidok.uni-freiburg.de:1174