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Root Uptake (root + uptake)
Selected AbstractsUptake and apoplastic retention of EDTA- and phytosiderophore-chelated chromium(III) in maizeJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2007Bülent E. Erenoglu Abstract Increasing the mobilization and root uptake of chromium (Cr) by synthetic and plant-borne chelators might be relevant for the design of phytoremediation strategies on Cr-contaminated sites. Short-term uptake studies in maize roots supplied with 51CrCl3 or 51Cr(III)-EDTA led to higher apoplastic Cr contents in plant roots supplied with 51CrCl3 and in Fe-sufficient plants relative to Fe-deficient plants, indicating that Fe stimulated co-precipitation of Cr. Concentration-dependent retention of Cr in a methanol:chloroform-treated cell-wall fraction was still saturable and in agreement with the predicted tendency of Cr(III) to precipitate as Cr(OH)3. To investigate a possible stimulation of Cr(III) uptake by phytosiderophores, Fe-deficient maize roots were exposed for 6 d to Cr(III)-EDTA or Cr(III)-DMA (2'-deoxymugineic acid). Relative to plants without Cr supply, the supply of both chelated Cr species in a subtoxic concentration of 1 µM resulted in alleviation of Fe deficiency,induced chlorosis and higher Cr accumulation. Long-term Cr accumulation from Cr(III)-DMA was similar to that from Cr(III)-EDTA, and Cr uptake from both chelates was not altered in the maize mutant ys1, which is defective in metal-phytosiderophore uptake. We therefore conclude that phytosiderophores increase Cr solubility similar to synthetic chelators like EDTA, but do not additionally contribute to Cr(III) uptake from Cr-contaminated sites. [source] Root cadmium desorption methods and their evaluation with compartmental modelingNEW PHYTOLOGIST, Issue 1 2010Wayne T. Buckley Summary ,Desorption of plant roots is often employed in studies of plant physiology and nutrition; however, there have been few studies on the validity of desorption procedures. ,Branched and in-line kinetic models with five compartments , cadmium (Cd)-chelate, Cd2+, root apoplast, root symplast and vacuole , were developed to evaluate the efficacy of diethylenetriaminepentaacetic acid (DTPA) and CaCl2 methods for the desorption of Cd from roots of durum wheat seedlings. Solution Cd2+ could exchange with apoplast and symplast Cd simultaneously in the branched model and sequentially in the in-line model. ,A 10-min desorption with 1 × 10,6 M DTPA at room temperature or cold (0°C) 5 × 10,3 M CaCl2 was required to achieve 99% recovery of apoplast-bound 109Cd when experimental results were interpreted with the branched model. However, when the same data sets were analysed with the in-line model, only partial desorption was achieved. Arguments are presented that suggest that the branched model is correct. ,It is suggested that compartmental modeling is a suitable tool for the study of plant root uptake and desorption kinetics, and that there are advantages over more commonly used calculation procedures. [source] Uncoupling nitrogen requirements for spring growth from root uptake in a young evergreen shrub (Rhododendron ferrugineum)NEW PHYTOLOGIST, Issue 3 2003T. Lamaze Abstract , , Internal cycling of nitrogen (N) was investigated in a subalpine field population of the evergreen shrub Rhododendron ferrugineum during spring growth. , , The foliar nitrogen of 5-yr-old-plants was directly labeled with 15N and subsequently traced to all plant compartments. In addition, 15N-ammonium uptake was estimated in glasshouse experiments. , , Before shoot growth, redistribution of 15N occurred in the plant without net N transfer. During spring development, the decreases in both leaf 15N and total N were almost identical in terms of percentage, and most of the 15N withdrawn from the leaf compartments was recovered in the growing shoots. Net changes in the N contents of the various leaf and woody compartments indicate that internal remobilization (especially from 1-yr-old leaves) could have met most of the N needs of new shoot growth. Simultaneously, the rate of mineral N uptake was very low. , , Thus, leaves in young plants provide N for new shoots (by contrast with old individuals) and allow, with woody tissues, almost complete uncoupling of N requirement for spring growth from root uptake. [source] Developmental Changes in Effect of Cytokinin and Gibberellin on Shoot K+ and Na+ Accumulation in Salt-Treated Sorghum PlantsPLANT BIOLOGY, Issue 4 2001G. N. Amzallag Abstract: The effect of cytokinin (CK) and/or gibberellin (GA) treatments on shoot accumulation of Na+ and K+ was investigated in Sorghum bicolor exposed to 150 mM NaCl. These hormonal treatments modified the shoot content of Na+ and K+, but the effect varied throughout development. Comparison of ion concentration versus ion content in shoots indicates that regulation of shoot concentration of K+ is modified during a transition period of development. This change is concomitant with reorganization of the regulation network for meristem activity, an event also involving changes in sensitivity to CK and GA. This evidence suggests a strong interdependency between dynamic changes in a between-organ network of relations and control of accumulation of monovalent ions in the shoot. Moreover, a new pattern of regulation of shoot Na+ concentration emerges during the transition period. During this process GA appears progressively involved in regulation of Na retranslocation, while CK is rather controlling the root uptake of Na+. Accordingly, the spontaneous emergence of Na-includer and Na-excluder individuals observed from an initially homogeneous population is interpreted as related to variations in sensitivity to GA and CK during differentiation of this newly emerging pathway of regulation. [source] | ||||||||||