Acclimation of potato plants to polyethylene glycol-induced water deficit I. Photosynthesis and metabolism |
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Authors: | Bussis D; Kauder F; Heineke D |
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Institution: | Albrecht-von-Haller Institut fur Pflanzenwissenschaften, Abteilung Biochemie der Pflanze, Untere Karspule 2, D-37073 Gottingen, Germany; Present address: Molecular Plant Physiology Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 2601, Australia; Corresponding author |
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Abstract: | The acclimation of photosynthesis and metabolism in response to water
deficit is characterized using hydroponically grown potato plants
(Solanum tuberosum cv. Désirée).
Plants were subjected to a reduced water potential of the nutrient solution
by adding 10% (w/v) PEG 6000. PEG-treated plants were retarded in growth.
Leaves which had been fully developed before the PEG treatment and leaves
grown during the PEG treatment showed different phenotypes and biochemical
and physiological properties. Photosynthesis of all leaves decreased during
the whole treatment. However, the decrease of photosynthesis in the two
types of leaves had different causes indicated by differences in their
metabolism. Leaves which were fully developed at the beginning of the PEG
treatment began to wilt starting from the leaf rim. The apoplastic ABA
content increased, coinciding with a decreased stomatal conductance.
Increased energy charge of the cells indicated impaired chloroplastic
metabolism, accompanied by a decrease of amounts of chloroplastic enzymes.
The apoplastic and the symplastic ABA content were increased during water
deficit and because ABA was concentrated in the cytosolic compartment it is
suggested that ABA is involved in decreasing photosynthetic enzyme contents
in old leaves. Young leaves, grown after the imposition of water deficit,
were smaller than control leaves and had a curly surface. In young leaves
apoplastic and cytosolic ABA contents were identical with control values.
Carboxylation efficiency of photosynthesis was decreased, but the water use
efficiency remained unchanged. Metabolic data of the photosynthetic
pathways indicate a down-regulation of chloroplastic metabolism. It is
concluded that in young leaves photosynthesis was non-stomatally limited.
This limitation was not caused by ABA. |
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