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Chilling induces a decrease in pyrophosphate‐dependent H + ‐accumulation associated with a ΔpH vac ‐stat in mung bean, a chill‐sensitive plant
Author(s) -
KAWAMURA YUKIO
Publication year - 2008
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2007.01762.x
Subject(s) - pyrophosphate , vacuole , biochemistry , chemistry , cytosol , hypocotyl , vesicle , cytoplasm , biophysics , biology , botany , enzyme , membrane
Chilling leads to cytoplasmic acidification in chill‐sensitive plants. A possible explanation for this observation is that a ΔpH‐stat between the cytosol and vacuole (ΔpH vac ‐stat) is perturbed by chilling. To understand the nature of this ΔpH vac ‐stat, the effect of temperature, between 20 and 0 °C, on pyrophosphate (PPi)‐ or ATP‐dependent acidification of vacuolar vesicles, isolated from mung bean hypocotyls, was determined. Over the temperature range investigated, the H + ‐influx mediated by PPase was balanced with the H + ‐efflux, which was PPi‐dependently suppressed, and consequently a constant pH in vesicles (pH in ) of ca. 5 was maintained against temperature changes. However, the ΔpH in driven by ATP decreased as the temperature dropped. Thus, the PPi‐dependent H + ‐accumulation may function as an essential factor to form a ΔpH vac ‐stat against temperature changes. Next, to study the chilling sensitivity of PPi‐dependent H + ‐accumulation, vacuolar vesicles were isolated from control seedlings or from seedlings chilled at 0 °C for 1 d. Chilling treatment resulted in a decrease in the H + ‐accumulation rate and in the steady‐state ΔpH in formed by PPi, the causes of which were enhanced by PPi‐dependent H + ‐efflux and reduced by H + ‐influx driven by PPase. Together, the results suggest that the decrease of PPi‐dependent H + ‐accumulation associated with the ΔpH vac ‐stat could result in cytoplasmic acidification.