1999 Fiscal Year Final Research Report Summary
Wall yielding of stem segments in adaptive growth recovery after osmotic stress
| Project/Area Number |
09640769
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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 |
植物生理
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| Research Institution | Nagoya University |
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Principal Investigator |
KATOU Kiyoshi Nagoya University, Sch. of Info. and Sci. Prof., 情報文化学部, 教授 (00109258)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Koji Sch. of Info. and Sci. Res. Assoc., 情報文化学部, 助手 (40283379)
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| Project Period (FY) |
1997 – 1999
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| Keywords | osmotic stress / adaptive growth / effective turgor / turgor / yield threshold / yieldin / cDNA cloning / cowpea |
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| Research Abstract |
Regulation of the in vivo wall yielding properties of the cell wall of Vigna hypocotyl segments during adaptive osmotic recovery of growth after osmotic stress was investigated by successive measurements using pressure-jump method. In the absence of IAA, cell wall extensibility showed no significant change under osmotic stress but effective turgor (P-Y) reduced to nearly zero, resulting in no growth recovery. In the presence of IAA, cell wall extensibility slightly decreased eve though growth recovered distinctly. Once extinguished effective turgor, however, fully recovered. It is effective turgor (driving force) that regulates wall yielding in growth recovery under osmotic stress. Intracellular pressure measurements revealed that the recovery of effective turgor is not caused by the regulation of P but Y. Y is always adjusted to about 60 kPa below the P that is comparable to the elevated effective turgor during IAA-induced growth promotion.
Wall bound protein yieldin that regulates pH-dependent yield threshold tension of glycerinated hollow cylinder (GHC) of cowpea hypocotyl was isolated from elongating hypocotyls of cowpea. Thus, cDNA of yieldin was cloned with RTPCR. The cDNA for yieldin contained an open reading frame of 981 base pairs encoding 327 amino acids. Recombinant yieldin expressed with E. coli showed potent activity of regulating the pH-dependent yield threshold tension of GHC. A homology search revealed that yieldin was homologous to acidic class III chitinase and concanavalin B. The chitinase activity, however, showed no direct relation to the yieldin activity. Mechanism of yieldin action remains to be studied.
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