Plants resistant to aluminium (Al) stress were isolated from Arabidopsis thaliana enhancer-tagged mutant lines. Compared with the parental Col-7 control line, one of the resistant candidates, #355-2, showed a higher expression of the F9E10.5 gene (At1g75100) on chromosome 1, a lower Al content in whole roots, and a shorter root hair length (approximately 30%). Both Al influx and associated oxid...

To determine the transporters responsible for toxic Na(+) influx in wheat (Triticum aestivum), root plasma membrane preparations were screened using the planar lipid bilayer technique as an assay for Na(+)-permeable ion channel activity. The predominant channel in the bilayer was a 44-pS channel that we called the nonselective cation (NSC) channel, which was nonselective for monovalent cations ...

It has recently been reported that plasmalemma electron transport may be involved in the generation of H(+) gradients and the uptake of ions into root tissue. We report here on the influence of extracellular NADH and ferricyanide on K(+) ((86)Rb(+)) influx, K(+) ((86)Rb(+)) efflux, net apparent H(+) efflux, and O(2) consumption in 2-centimeter corn (Zea mays [A632 x Oh43]) root segments and int...

This study measured total osmolarity and concentrations of NH(4)(+), NO(3)(-), K(+), soluble carbohydrates, and organic acids in maize seminal roots as a function of distance from the apex, and NH(4)(+) and NO(3)(-) in xylem sap for plants receiving NH(4)(+) or NO(3)(-) as a sole N-source, NH(4)(+) plus NO(3)(-), or no nitrogen at all. The disparity between net deposition rates and net exogenou...

High Cd content in durum wheat (Triticum turgidum L. var durum) grain grown in the United States and Canada presents potential health and economic problems for consumers and growers. In an effort to understand the biological processes that result in excess Cd accumulation, root Cd uptake and xylem translocation to shoots in seedlings of bread wheat (Triticum aestivum L.) and durum wheat cultiva...

2.1 NITROGEN AND IT ROLE IN THE PLANT.................................................................................... 3 2.2 THE PLANT NITROGEN STATUS ................................................................................................ 4 2.3 PLANT AVAILABLE NITROGEN ................................................................................................. 5 2.3.1 Root inte...

Futile transmembrane NH3/NH4(+) cycling in plant root cells, characterized by extremely rapid fluxes and high efflux to influx ratios, has been successfully linked to NH3/NH4(+) toxicity. Surprisingly, the fundamental question of which species of the conjugate pair (NH3 or NH4(+)) participates in such fluxes is unresolved. Using flux analyses with the short-lived radioisotope (13)N and electrop...

Active K(+) influx was studied in apical segments from maize (Zea mays L., hybrid lines XL 342) and pea (Pisum sativum L. var Laxton superbo) seedlings pretreated with the herbicide chlorsulfuron (2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl) aminocarbonyl]benzenesulfonamide).Even though both plants were sensitive to chlorsulfuron, a strong inhibition of K(+) uptake only was evident in ma...

Corn roots or washed corn root tissue exposed to cold shock absorb 20 to 24% more (45)Ca(2+) into a nonexchangeable phase than control roots. Addition to fusicoccin largely prevents this additional calcium influx. The results are discussed in relation to injury-induced changes in membrane permeability of root cell membranes.

NH(4)(+) acquisition by plant roots is thought to involve members of the NH(4)(+) transporter family (AMT) found in plants, yeast, bacteria, and mammals. In Arabidopsis, there are six AMT genes of which AtAMT1;1 demonstrates the highest affinity for NH(4)(+). Ammonium influx into roots and AtAMT1;1 mRNA expression levels are highly correlated diurnally and when plant nitrogen (N) status is vari...