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Proton efflux from corn roots induced by tripropyltin.
1Department of Botany, University of Illinois, Urbana, Illinois 61801.
Plant Physiology
|October 1, 1981
Summary
Tripropyltin partially restores proton efflux in corn roots but does not drive potassium influx. Instead, tripropyltin-induced chloride efflux accounts for medium acidification, suggesting a novel ion transport mechanism in plant roots.
Area of Science:
- Plant Physiology
- Ion Transport Mechanisms
- Root Biology
Background:
- Electrogenic proton (H+) efflux is crucial for plant root function, including nutrient uptake.
- ATPase inhibitors and tissue injury disrupt normal H+ efflux.
- Understanding alternative mechanisms for medium acidification is important for plant science.
Purpose of the Study:
- To investigate the effect of tripropyltin on medium acidification in washed corn root tissue.
- To determine the mechanism by which tripropyltin restores H+ efflux.
- To elucidate the role of ion exchange in tripropyltin-induced acidification.
Main Methods:
- Washed corn root tissue preparation.
- Measurement of medium acidification.
- Assessment of electrogenic H+ efflux and K+ influx.
- Analysis of chloride (Cl-) efflux.
- Comparison with nigericin-induced acidification.
Main Results:
- Tripropyltin restored H+ efflux in inhibited/injured corn root tissue.
- The restored H+ efflux was not electrogenic and did not drive K+ influx.
- Tripropyltin significantly increased endogenous Cl- efflux (5-fold).
- Cl-/OH- exchange explained the observed medium acidification by tripropyltin.
- This mechanism did not apply to nigericin-induced acidification.
Conclusions:
- Tripropyltin-induced medium acidification in corn roots is primarily mediated by Cl-/OH- exchange, not electrogenic H+ transport.
- Tripropyltin inhibits K+ influx independently.
- The findings reveal a non-electrogenic mechanism contributing to root medium acidification.