2004 Fiscal Year Final Research Report Summary
Molecular study on usage of unused available resources from northern trees
| Project/Area Number |
14360093
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
林産学
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| Research Institution | Hokkaido University |
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Principal Investigator |
FUJIKAWA Seizo Hokkaido Univ., Grad.School of Agr., Prof., 大学院・農学研究科, 教授 (50091492)
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| Co-Investigator(Kenkyū-buntansha) |
FUNADA Ryo Hokkaido Univ., Grad.School of Agr., Asso.Prof., 大学院・農学研究科, 助教授 (20192734)
SANO Yuzou Hokkaido Univ., Grad.School of Agr., Assi.Prof, 大学院・農学研究科, 助手 (90226043)
ARAKAWA Keita Hokkaido Univ., Inst.of Low Temperature Sci., Assi.Prof, 低温科学研究所, 助手 (00241381)
TAKEZAWA Daisuke Hokkaido Univ., Inst.of Low Temperature Sci., Assi.Prof, 低温科学研究所, 助手 (20281834)
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| Project Period (FY) |
2002 – 2004
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| Keywords | northern trees / freezing resistance / biotechnology / low temperature-induced gene / dehydration tolerance / supercooling / antifreeze protein / anti ice nucleater |
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| Research Abstract |
We studied freezing adaptation mechanisms of northern trees including the cortical and xylem parenchyma cells at molecular level.
Cortical parenchyma cells of the northern trees adapt to subfreezing temperatures by extracellular freezing. These cells can adapt freezing even to liquid nitrogen temperature by obtaining high tolerance to freezing-induced dehydration. We identified that group 3 LEA proteins were specifically accumulated in ER of the cortical parenchyma cells of mulberry during winter. We named this protein as WAP27 and examined the function both in planta and in vitro. Transgenic Arabidopsis plants introduced WAP27 obtained higher freezing tolerance after cold acclimation as compared with wild type plants. Furthermore, purified WAP27 had cryoprotective activity to freezing sensitive proteins, such as LDH.
Xylem parenchyma cells of trees, on the other hand, adapt to subfreezing temperatures by deep supercooling. The xylem parenchyma cells from northern trees can supercool -60
… More
C. In order to examine mechanisms that water keep supercooling in xylem parenchyma cells, we analyzed gene expression, accumulation of proteins and soluble sugars. With comprehensive gene analysis about xylem of Larch, we could find several genes that were never reported as cold-induced genes in plants. We confirmed by northern blot analysis hat these genes were expressed in parallel with increased supercooling ability. On protein analysis using beech, we could identified a few tens protein-spots that were specifically accumulated in parallel with increased supercooling ability. Among these proteins, we purified chitinase-like proteins, which are known as one of antifreezing proteins in plants, and antifreeze activity was examined with negative result. We also analyzed soluble proteins in xylem of birch. However, the accumulation was same with the cortical parenchyma cells that adapt to subfreezing temperature by extracellular freezing. Finally, we obtained crude extracts from xylem (parenchyma cells) and the effect to supercooling of water was examined. We could find that the crude extracts from xylem that exhibited high supercooling in the parenchyma cells provided high ability of supercooling to water. Now, we are continuing identifications of substances within crude extracts that may provide high supercooling.
Our results showed that winter-induced genes and gene products from northern trees that exhibit extraordinary high freezing resistance may be useful resources for developing crops with high freezing resistance as well as for the use of them for freezing regulate substances in wide range of industries. Less
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