| Research Abstract |
Plants' morphogenesis depends very much on light conditions. Such responses of plants, often referred to as phomorphogenesis, are mediated mainly by a red/far-red light photoreceptor, phytochrome, and a blue light photoreceptor, cryptochrome. In the present study, we investigated photoperceptive sites of these responses. For this purpose, we employed light-responsive promoter/enhancer trap lines as well as transgenic plants that express phytochrome in certain tissues/organs. At the same time, we analyzed EID1/SBL1 protein by molecular biological techniques. Furthermore, a structure/function study of phytochrome was conducted
First, we screened for promoter/enhancer trap lines that exhibited light-dependent expression of the reporter gene, GUS.Analysis of such lines suggested that a plant hormone, auxin, is involved in the photomorphogenic responses. We then established transgenic lines in which phyB-GFP was expressed in certain parts of the, seedling. Physiological analysis of such plants indicated that hypocotyl elongation is regulated primarily by phyB in cotyledons and secondarily by phyB in vascular bundle. We further found that the latter function of phyB depends on cry1, We have also tried to identify, factors interacting with EID1/SBLl protein but failed. In addition, we have shown that the C-terminal domain of phyB is dispensable for the signal transduction activity of phyB in the nucleus
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