| Budget Amount *help |
¥14,500,000 (Direct Cost: ¥14,500,000)
Fiscal Year 2006: ¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 2005: ¥7,500,000 (Direct Cost: ¥7,500,000)
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| Research Abstract |
We expressed cry2-GFP in tissue-specific manners with the aids of tissue specific promoters. The constructs were transformed into the cry2 mutant of Arabidopsis. Detailed analyses of those lines indicated that cry2-GFP that was expressed in the vascular bundles effectively promoted the flowering. By contrast, those expressed in other tissues were not effective. We also confirmed that cry2-GFP promoted the expression of FT, a key regulator of flowering, in vascular bundles. These observations are in striking contrast with those for phyB, which functions in the mesophyll rather than vascular bundles. Taken together, our work has demonstrated that photoreceptors are functioning in spatially separate parts of the leaf and communications between those different tissues exsit.
We analyzed amino acid substitutions in the N-terminal moiety of phyB. In this year, we focused on the mutations that reduced the signaling activity of the molecule without changing its spectral nature. Three of four such mutations were fund in the PAS domain whereas the remaining one was found within the GAF domain. We introduced those mutations one by on into the full-length phyB and expressed them in the phyB mutant of Arabidopsis. As expected, those mutated molecules exhibited reduced signaling activity in planta.
To examine the site of phyA signal transduction, we expressed phyA-GFP with or without the nuclear localization signal (NLS) or nuclear export signal (NES). The constructed genes were placed downstream of the authentic PHYA gene promoter and transformed into the phyA mutant of Arabidopsis. We then tested those lines with respect to the responses to continuous far-red light. Such responses are known as FR-HIR responses, which is controlled solely by phyA. As expected, phyA-GFP with NLS responded almost normally to the treatment whereas that with NES did not. Hence, as is the case with phyB, the nucleus is an important site for the phyA signal transduction.
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