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Comparison of the effect of rapidly and gradually developing water‐stress on carbohydrate metabolism in spinach leaves
Author(s) -
ZRENNER R.,
STITT M.
Publication year - 1991
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1991.tb00963.x
Subject(s) - sucrose , spinacia , starch , spinach , photosynthesis , chemistry , sucrose phosphate synthase , carbohydrate , wilting , crassulacean acid metabolism , fructose , horticulture , botany , sugar , sorbitol , hexose , phosphate , distilled water , food science , sucrose synthase , chloroplast , biology , biochemistry , invertase , chromatography , enzyme , gene
. The effect of water‐stress on photosynthetic carbon metabolism in spinach ( Spinacia oleracea L.) has been studied in experiments in which water‐stress was induced rapidly by floating leaf discs on sorbitol solutions or wilting detached leaves, and in experiments in which water‐stress was allowed to develop gradually in whole plants as the soil dried out. In both short‐ and long‐term water stress, the rate of photosynthesis in saturating CO 2 did not decrease until leaf water potential decreased below ‐1.0 MPa. However, at smaller water deficits there was already an inhibition of starch synthesis, while sucrose synthesis remained constant or increased. This change in partitioning was accompanied by an increase in activation of sucrose‐phosphate synthase (revealed as an increase in activity assayed in the presence of low hexose‐phosphate and inorganic phosphate, while the activity assayed with saturating hexosephosphates remained unaltered). Water‐stressed leaves had a two‐ to three‐fold higher sucrose content at the end of the night, and contained less starch than non‐stressed leaves. When leaves were held in the dark, sucrose was mobilized initially, while starch was not mobilized until the sucrose had decreased to a low level; in water‐stressed leaves, starch mobilization commenced at a two‐fold higher sucrose content. It is concluded that water‐stressed leaves maintain higher sucrose and lower starch levels than non‐stressed leaves. This response is found in rapid and long‐term stress, and represents an inherent response to water deficits.