The effects of soil humic matter on the uptake of ions by oat roots and on the (Mg2++K+) ATPase activity, responsible for energy transduction for ion transport at cell membrane, were studied. Four-day-old roots treated for 8 h with unfractionated humic solution (50 μg org C × ml−1) took up K+ and SO4staggered−2 ions at rates, respectively, 33% and 106% higher than the controls. Similar effects were caused by humic and fulvic acids, and by the hot-acid soluble and hot-acid insoluble fractions prepared from humic acids. At org C concentration higher than 1 μg ml−1, the humic extract inhibited both Mg2+ dependent and K+-stimulated ATPase activities of microsomes isolated from roots. At 0.33–1 μg org C ml−1, the Mg2+-dependent activity was inhibited, whereas the activity stimulated by K+ increased. Humic acids and the acid-insoluble fraction inhibited the ATPase activity more than fulvic acids and the acid-soluble fraction. Preliminary results of SDS - PAG electrophoresis of membrane proteins showed two polypeptides associated with membrane of humus treated roots, which where absent in the control.

Action of soil humic matter on plant roots, stimulation of ion uptake and effects on (Mg2++K+)ATPase activity

VARANINI, Zeno;
1987-01-01

Abstract

The effects of soil humic matter on the uptake of ions by oat roots and on the (Mg2++K+) ATPase activity, responsible for energy transduction for ion transport at cell membrane, were studied. Four-day-old roots treated for 8 h with unfractionated humic solution (50 μg org C × ml−1) took up K+ and SO4staggered−2 ions at rates, respectively, 33% and 106% higher than the controls. Similar effects were caused by humic and fulvic acids, and by the hot-acid soluble and hot-acid insoluble fractions prepared from humic acids. At org C concentration higher than 1 μg ml−1, the humic extract inhibited both Mg2+ dependent and K+-stimulated ATPase activities of microsomes isolated from roots. At 0.33–1 μg org C ml−1, the Mg2+-dependent activity was inhibited, whereas the activity stimulated by K+ increased. Humic acids and the acid-insoluble fraction inhibited the ATPase activity more than fulvic acids and the acid-soluble fraction. Preliminary results of SDS - PAG electrophoresis of membrane proteins showed two polypeptides associated with membrane of humus treated roots, which where absent in the control.
1987
humic substances; ion uptake; Mg2++K+ATPase
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/376219
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