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Plant Physiology 95:504-508 (1991) © 1991 American Society of Plant Biologists Comparison of Temperature Dependency of Tonoplast Proton Translocation between Plants Sensitive and Insensitive to Chilling 1The Institute of Low Temperature Science, Hokkaido University, Sapporo 060, Japan
Proton transport activities in isolated tonoplast vesicles were measured as quenching of fluorescence of acridine orange. A marked difference in the temperature dependency of two types of tonoplast proton transports, i.e. ATP- and pyrophosphate-driven, was observed between two leguminous plants sensitive (mung bean, Vigna radiata [L.] Wilczek) and insensitive (pea, Pisum sativum L.) to chilling. In tonoplast vesicles isolated from hypcotyls of mung bean seedlings that were germinated for 3.5 days at 26°C in the dark, the total amount of fluorescence quenching at the steady state in both types of proton pumps, as a measurement of the inside-acidic pH gradient across the membrane vesicles, was markedly suppressed under temperatures below 10°C. In tonoplast vesicles isolated from epicotyls of pea seedlings, which were germinated for 7 days at 18° to 23°C in the dark, no suppression occurred in the formations of the pH gradient in either type of proton pump, even at 0°C. The cause of the low temperature-induced suppression of the proton pumps in mung bean tonoplasts seems to be not an increased permeability of the membrane vesicles to protons or accompanying anions and cations, but instead a marked inhibition in the catalytic activity of both enzymes under low temperatures.
1 Supported in part by Grant-in-aid 62304004 and 01480009 for Scientific Research from the Ministry of Education, Science and Culture. Contribution No. 3412 from the Institute of Low Temperature Science. This article has been cited by other articles:
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