1988 Fiscal Year Final Research Report Summary
Changes of H^+-pumping activity of the vesicles prepared from plant roots grown under salt stress
| Project/Area Number |
62480052
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
土壌・肥料
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| Research Institution | Okayama University |
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Principal Investigator |
MATSUMOTO Hideaki Res. Inst. for Bioresources, Okayama Univ. Assoc. Prof, 資源生物科学研究所, 助教授 (80026418)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Higher plant / Salt stress / Physiological disorder / Cell membrane / Ion transport / Proton pump / ATP分解酵素 |
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| Research Abstract |
Proton extrusion from cucumber roots decrease markedly during Ca^<2+> starvation. The proton transport rate of the vesicles from Ca^<2+>-starved root was repressed to less than half of the vesicles from control roots. K^+-Mg^<2+>-ATPase activity associated with the vesicles decreased markedly by Ca^<2+> deficiency. Partially lipid-depleted ATPase prepared from plasma membrane of cucumber roots reassociated with asolection, soybean lecitin. The activity of reassociated ATPase obtained from the control roots was apparently higher than the activity of Ca^<2+>-starved roots. The amount of asolectin required for maximum activation of the partially lipid-depleted ATPase prepared from control roots was much lower than that prepared from Ca^<2+>-starved roots. A decrease in the functional association of ATPase with phospholipids might be one of the physiological injuries in root cell membranes of cucumber caused by Ca^<2+> deficiency.
H^+-transport activity of the vesicles prepared from barley
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roots increased with 200 mM NaCl stress. This increase was suppressed in the presence of inhibitors of protein synthesis. The properties of the membrane vesicles associated with H^+-transport activity suggested that membrane was tonoplast origin. The density gradient centrifugation of vesicles associated with H^+-transport activity showed no detectable difference and Km values for ATP of the H^+-transport activity of vesicles from control and NaCl-stressed roots were the same. These results suggest that the sequestration of the salts into vacuoles is carried out by the increased proton pump associated with the tonoplast. This could be an adaptive mechanism of barley against salt stress.
The extrusion of protons from barley roos decreased markedly after the treatment with 1 mM AlCl_3. H^+-transport activity of the membrane vesicles was inhibited by approximately 50% in the presence of 100 M AlCl_3 at pH 6.5 but the inhibition was only 10% at pH 7.5 . The values of Vmax and Km for ATP related to the H^+-transport activity of the vesicles due to Al was effectively restored by citric acid. The results suggest that one of the mechanism of Al toxicity in plant roots is the inhibition of the H^+ transport activity which in turn leads to the inhibition of proton extrusion from the roots. Less
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Research Products
(14 results)
