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Phosphate Regulation of Nitrate Assimilation in Soybean 总被引:23,自引:1,他引:23
RUFTY THOMAS W. JR; ISRAEL DANIEL W.; VOLK RICHARD J.; QIU JINSHU; SA TONGMIN 《Journal of experimental botany》1993,44(5):879-891
It is known that phosphorus deficiency results in alterationsin the assimilation of nitrogen. An experiment was conductedto investigate mechanisms involved in altered 15NO3 uptake,endogenous 15N translocation, and amino acid accumulation insoybean (Glycine max L. Merrill, cv. Ransom) plants deprivedof an external phosphorus supply for 20 d in solution culture.Phosphorus deprivation led to decreased rates of 15NO3uptake and increased accumulation of absorbed 15N in the root.Both effects became more pronounced with time. Asparagine, theprimary transport amino acid in soybean, accumulated in largeexcess in roots and stems. In roots of phosphorus-deprived plants,concentrations of ATP and inorganic phosphate declined rapidly,but dry weight accumulation was similar to or above that ofthe control even after 20 d of treatment. Arginine accumulationin leaves was greatly enhanced, even though 15N partitioninginto the insoluble reduced-N fraction of leaves was unaffected.The results suggest that decreases in NO3 uptake in lowphosphorus plants could be caused by feedback control factorsand by limited ATP availability. The decline in endogenous Ntransport from the root to the shoot may be associated withchanges in membrane properties, which also result in paralleleffects on hydraulic conductance and the upward flow of waterthrough the plant. Key words: Phosphorus stress, nitrate uptake, nitrate translocation, arginine 相似文献
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