1996 Fiscal Year Final Research Report Summary
Morpho-physiological studies on gas exclusion system of a crop root relating to salt and drought tolerances
| Project/Area Number |
07456009
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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 |
作物学
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| Research Institution | Okayama University |
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Principal Investigator |
HIRAI Yoshihiko Okayama Univ., Fac.of Agr., Research Associate, 農学部, 助手 (80263622)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Gas exclusion / Dissolved gas / Drought tolerance / Salt tolerance / Rice |
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| Research Abstract |
It is reported that cavitation, i.e.bubbles in xylem solution produced by negative pessure, prevents water absorption and occurs only in plants which suffer severe drought stress. This suggests a possibility of dissolved-gas exclusion in the process of water absorption in plant roots. In this research, a mechanism of gas exclusion, structural characteristics and gas exclusion ratio in several gases were studied.
Dissolved-gas content in xylem sap was compared with that in root culture solution by using rice and barley roots. Xylem sap was sampled from the stele of proximal end of a excised root exposed to air- or nitrogen gas-saturated distillled water with 0.3 or 0.5 MPa of hydraulic pressure. As a result, a root has a function to exclude dissolved gas from culture solution in the process of water uptake.
The gas exclusion rate (1-Gr/Gc, Gr : dissolved-gas content in root xylem, Gc : dissolved-gas content in culture solution) of rice roots which grown under different drought stress conditions was investigated. The gas exclusion rate of a root grown under severe drought stress condition was higher. In those roots, the intense fluorescence in cortical sclerenchyma and endodermis was induced by using a berberine-aniline blue fluorescent staining procedure. This suggest that the gas exclusion rate relate to the component of the root.
The gas exclusion rate of rice roots exposed oxygen or nitrogen gas-saturated distillled water were investigated. The gas exclusion rate of oxygen gas was higher. This suggest that each gases in culture solution are excluded separately in plant root.
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