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Acclimation of potato plants to polyethylene glycol-induced water deficit I. Photosynthesis and metabolism 总被引:5,自引:0,他引:5
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. 相似文献
2.
Acclimation of potato plants to polyethylene glycol-induced water deficit II. Contents and subcellular distribution of organic solutes 总被引:2,自引:0,他引:2
Potato plants (Solanum tuberosum cv.
Désirée) were grown hydroponically and subjected to
water deficit induced by addition of 10% (w/v) PEG 6000. The potato plants
were able to grow under water deficit by accumulating organic solutes
(osmoregulation). Osmoregulation occurred in two phases. During the initial
2d hexoses were accumulated, and after 7 d of PEG treatment osmotic
adjustment was mostly due to the accumulation of amino acids, especially
proline, which accumulated up to 150 times the control content. Sucrose
contents remained unchanged in leaves of PEG-treated plants compared with
controls, whereas the starch content decreased during PEG treatment.In
control leaves, the hexoses and malate were compartmented in the vacuole
and sucrose was found in the cytosol and vacuole. Amino acids were
distributed between the cytosol and stroma, but only minor amounts of amino
acids could be detected in the vacuole. Under water deficit the subcellular
distribution of hexoses, malate and sucrose remained unchanged. Most amino
acids showed a slight to moderate higher concentration in the vacuole under
water deficit. Proline, the metabolite contributing mainly to
osmoregulation, was concentrated mostly in the chloroplast and the cytosol.
This underlines the important role of proline as the osmolyte under water
deficit. 相似文献
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