Using the short-lived radiotracer 13N, we examined the hypothesis that toxic, futile ammonia/ammonium (NH3/NH4+) fluxes at high external concentrations are mediated by ammonia-transporting aquaporins in roots of intact barley (Hordeum vulgare L.) plants. Effects of the aquaporin inhibitors zinc, copper, mercury, gold, silver, hydrogen peroxide, propionic acid, and nitrogen gas supported this hypothesis. Further tests with these inhibitors showed that changes in plant water potential and water content could be linked to NH3/NH4+ fluxes. An increase in external pH, causing an increase of NH3 in the nutrient solution, resulted in large increases of 13N influx, which can only be explained in energetic terms if the transported solute is neutrally charged. Taken together, the evidence here strongly supports the proposed hypothesis.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/27327 |
| Date | 27 May 2011 |
| Creators | Becker, Alexander |
| Contributors | Kronzucker, Herbert |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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