Competitive Al sup 3+ inhibition of net Mg sup 2+ uptake by intact Lolium multiflorum roots

Journal Article · Fri Dec 01 04:00:00 EST 1989 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.91.4.1407· OSTI ID:5950965

Rengel, Z; Robinson, D L ^[1]

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1. Louisiana State Univ. Agricultural Center, Baton Rouge (USA)

Aluminum impairs uptake of Mg{sup 2+}, but the mechanisms of this inhibition are not understood. The depletion technique was used to monitor net Mg{sup 2+} uptake from nutrient solution by intact, 23-day-old plants of ryegrass (Lolium multiflorum Lam., cv Gulf and Wilo). Activities of Mg{sup 2+} and monomeric Al species in nutrient solution were calculated and used as the basis for expressing the results. The kinetics of net Mg{sup 2+} absorption was resolved into (a) a transpiration-dependent uptake component, (b) a metabolically mediated, discontinuous saturable component that is Al{sup 3+} sensitive and p-chloromercuribenzene sulfonic acid (PCMBS) resistant, and (c) a linear, carbonyl cyanide m-chlorophenylhydrazone resistant, Al{sup 3+} sensitive component that might be a type of facilitated diffusion. Lowering the pH from 6.0 to 4.2 exerted a noncompetitive inhibition of net Mg{sup 2+} uptake, while aluminum at 6.6 micromolar Al{sup 3+} activity exerted competitive inhibition of net Mg{sup 2+} uptake at pH 4.2. The Al{sup 3+}-induced effect was obvious after 30 minutes. Cultivar-specific ability to retain a higher affinity for Mg{sup 2+} by postulated transport proteins in the presence of Al{sup 3+} might be one of the mechanisms of differential Al tolerance among ryegrass cultivars.

• OSTI ID: 5950965
• Journal Information: Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 91:4; ISSN 0032-0889; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALINE EARTH METALS
ALUMINIUM
BIOCHEMICAL REACTION KINETICS
CEREALS
ELEMENTS
GRASS
KINETICS
LILIOPSIDA
MAGNESIUM
MAGNOLIOPHYTA
METALS
PLANTS
REACTION KINETICS
ROOTS
RYE
TOXICITY
UPTAKE