Molecular cloning and characterization of a sodium-pump ATPase of the moss Physcomitrella patens |
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Authors: | Benito Begoña Rodríguez-Navarro Alonso |
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Affiliation: | Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, 28040 Madrid, Spain. |
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Abstract: | Physcomitrella patens grew slowly at 600 mm Na+, pH 6.0, affected by the low water potential but without signs of suffering Na+ toxicity. At pH 8.0, tolerance seemed to be lower but it grew at 200 mm Na+, again without signs of Na+ toxicity. The resistance of Physcomitrella cells to the toxic effects of Na+ can be accounted for by their capacity to keep high K+:Na+ ratios and to extrude Na+ by a system that is not dependent on DeltapH. Physcomitrella expresses two P-type ATPases similar in sequence to fungal ENA-type Na+-ATPases. A functional study in yeast demonstrated that one of these ATPases, PpENA1, is an Na+-pump. We also found that P. patens has a plant-type SOS1 Na+/H+ antiporter. We discuss that Na+-ATPases existed in early land plants but that they were lost during the evolution of bryophytes to flowering plants. |
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Keywords: | Physcomitrella sodium pump sodium efflux sodium tolerance |
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