Modifying Effects of a Non-Toxic Level of Aluminium on Phosphate Fluxes and Compartmentation in Root Cortex Cells of Intact Ryegrass Seedlings |
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Authors: | MACKLON, A. E. S. SIM, A. |
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Abstract: | From compartmental analysis of 32P elution measurements, concentrationsand fluxes of phosphate were estimated for root cortical cellsof intact Lolium perenne L. plants, when in complete nutrientsolution containing 0.1 mol m3 phosphate with and without37 mmol m3 Al during loading and elution. Failure ofthe data, when plotted as ct. min1 remaining in the tissueas a function of time, to meet the criteria for first orderkinetics led to a discussion of the relative importance of transportto the shoot, assimilation, and complexation in the vacuole,in causing this discrepancy. It was concluded that complexationwas the most important factor. Transformation of the data tomeet the criteria for first order kinetics gave corrected valuesfor compartmental concentrations and fluxes of phosphate, andestimates of the size of the otherwise unresolved slowly exchangingcompartment within the vacuole equated with condensed phosphate.In the control this was 2.5 mol m3 P but in Al treatmentsa much larger amount of phosphate was complexed with Al (6.5mol m3 P). Phosphate transport to the shoot was unaffectedby Al. Instead, levels of Al, common in solution in upland soils,sequestered in the root vacuoles quantities of phosphate significantfor stressing the phosphate economy of nutrient-poor grassland. Key words: Lolium perenne L. phosphate, aluminium, compartmentation, complexation |
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