Solute accumulation and decreased photosynthesis in leaves of potato plants expressing yeast-derived invertase either in the apoplast, vacuole or cytosol |
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Authors: | Dirk Büssis Dieter Heineke Uwe Sonnewald Lothar Willmitzer Klaus Raschke Hans-Walter Heldt |
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Institution: | Institut für Biochemie der Pflanze, Untere Karspüle 2, D-37073 G?ttingen, Germany, DE Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse 3, D-06466 Gatersleben, Germany, DE Max-Planck-Institut für Molekulare Pflanzenphysiologie, Karl-Liebknecht-Str. 25, D-14476 Golm, Germany, DE Pflanzenphysiologisches Institut, Untere Karspüle 2, D-37073 G?ttingen, Germany, DE
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Abstract: | Potato (Solanum tuberosum cv. Désirée) plants expressing yeast invertase directed either to the apoplast, vacuole or cytosol were biochemically and
physiologically characterised. All lines of transgenic plants showed similarities to plants growing under water stress. Transformants
were retarded in growth, and accumulated hexoses and amino acids, especially proline, to levels up to 40-fold higher than
those of the wild types. In all transformants rates of CO2 assimilation and leaf conductance were reduced. From the unchanged intercellular partial pressure of CO2 and apoplastic cis-abscisic acid (ABA) content of transformed leaves it was concluded that the reduced rate of CO2 assimilation was not caused by a limitation in the availability of CO2 for␣the ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco). In the transformants the amount of Rubisco protein was
not reduced, but both activation state and carboxylation efficiency of photosynthesis were lowered. In vacuolar and cytosolic
transformants this inhibition of Rubisco might be caused by a changed ratio of organic bound and inorganic phosphate, as indicated
by a doubling of phosphorylated intermediates. But in apoplastic transformants the pattern of phosphorylated intermediates
resembled that of leaves of water-stressed potato plants, although the cause of inhibition of photosynthesis was not identical.
Whereas in water-stressed plants increased contents of the phytohormone ABA are supposed to mediate the adaptation to water
stress, no contribution of ABA to reduction of photosynthesis could be detected in invertase transformants.
Received: 29 May 1996 / Accepted: 30 December 1996 |
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Keywords: | : Invertase overexpression Photosynthesis Solanum (invertase overexpression) Transgenic plant (potato) Water stress |
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