2005 Fiscal Year Final Research Report Summary
REGULATION OF TUBEROUS ROOT FORMATION BY D-TYPE CYCLIN IN SWEET POTATO
| Project/Area Number |
16580012
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Crop science/Weed science
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
SAITOU Kazuyuki Kyushu University, Faculty of Agriculture, Associate Professor, 大学院・農学研究院, 助教授 (00215534)
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| Project Period (FY) |
2004 – 2005
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| Keywords | SWEET POTATO / CYCLIN D / TUBEROUS ROOT FORMATION / SUCROSE / CYTOKININ / ABA |
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| Research Abstract |
Two cDNAs for D3-type cyclins were cloned and designated Ipoba;CycD3;1 and Ipoba;CycD3;2. The deduced amino acid sequences for Ipoba;CycD3;1 and Ipoba;CycD3;2 contained a retinoblastoma-binding motif and a cyclin box, whereas they shared only 49% identity. In the process of tuberous root formation, Ipoba;CycD3;1 was expressed in thick roots and tuberous roots at the highest level. The Ipoba;CycD3;2 gene expression reached a maximum level in thick roots. The transcript level of ADP-glucose pyrophosphorylase large subunit iAGPLI-1 increased continuously. In order to clarify the effect of sucrose and plant hormones on gene expression more precisely, leaf-petiole cuttings were used. The expression of Ipoba;CycD3;1 increased stepwise by application of 50 mM and 100 mM sucrose solution, and the highest expression level was obtained with 100 mM and 150 mM sucrose. A hundred mM was optimal for maximum expression of Ipoba;CycD3;2. The expression of iAGPLI-1 gene kept an increasing tendency with
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an increase in sucrose concentration up to 150 mM. Benzyladenine induced the expression of Ipoba;CycD3;1 and enhanced sucrose induction of Ipoba;CycD3;1 expression. The relative amount of Ipoba;CycD3;2 mRNA was slightly reduced by benzyladenine, while the transcripts increased in response to benzyladenine when sucrose was supplemented. The induction of iAGPLI-1 by sucrose was repressed by benzyladenine. ABA reduced the relative amount of Ipoba;CycD3;1 mRNA. Sucrose antagonized the inhibitory effect of ABA for Ipoba;CycD3;1 gene expression. The expression of Ipoba;CycD3;2 was not influenced by ABA. iAGPLI-1 gene expression was not significantly affected by ABA, whereas the induction of iAGPLI-1 by sucrose was inhibited by ABA. These results suggested that cell proliferation and storage parenchyma differetiation in the process of tuberous root formation were controlled via regulation of D3 cyclins and ADP-glucose pyrophosphorylase gene expression by alterations in the concentration of sucrose, cytokinin and ABA. Less
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