| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
(1)Production of an esr1/esr2 double mutant
ESR1 is thought to be play a key role in initiation of shoot regeneration in tissue culture. ESR1 encodes a putative transcription factor belonging to the AP2/ERF family.
Although an esr1/esr2 double mutant was produced using a mutant arabidopsis plant in which the ESR2 gene was disrupted with an exogenous transposable element, En-1, its phenotypes were unstable since En-1 autonomously transposed at a high frequency. To avoid this problem, we obtained a plant earring a foot print after transpostion of En-1, which cause a frameshift in the ESR2 gene. We are producing an esr1/esr2 double mutant using the plant and investigating its phenotypes during development.
(2)Screening of target genes by ESR1-regulation using a plant expressing ESR1-Est
ESR1/ESR2 encode AP2/ERF class transcription factors. In order to identify their target genes, transgenic arabidopsis plants expressing ESR1-Est protein, whose translocation into nuclei can be regulated with e
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strogen, were produced. Genes whose mRNA levels were differentially regulated with estrogen were screened using microarrays. As the results, some genes encoding transcription factors, bHLH,Dof protein, Myb4,Myb7 were identified as target candidates. We are investigating their expression patterns in shoot regeneration and effects of their overexpression on shoot regeneration efficiencies at present.
(3)Analysis of functional domains of ESR1
We examined the DNA-binding potential of ESR1 for specific sequences. Recombinant ESR1 protein specifically bound to the GCC box, known as the ethylene-responsive element. In addition, ESR1 was localized to the nucleus when expressed in onion epidermal cells. Deletion experiments revealed that the DNA-binding domain or the C-terminal region of ESR1 is essential for ESR1 overexpression to enhance shoot regeneration. The C-terminal region may be involved in transcriptional regulation by ESR1. These results suggest that ESR1 functions as a transcription factor and that its transcriptional regulation is important for the initiation of shoot regeneration. Less
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