Effect of aluminium on ion uptake and H⁺ release by maize

Abstract

SUMMARYThe aim of this study was to quantify the long-term effects of Al in solution on mineral ion uptake and associated H^ release by the roots of maize cultivated in conditions compatible with field data. Two maize {Zea mays L.) cvs of differing sensitivity to Al were compared. The culture w^as conducted in hydroponic conditions for culture periods of 2-5 d in the presence of 0-30 /xm Al. Proton fluxes were localized along the roots using a videodensitometry method with bromocresol green on agarose gel.Aluminium reduced the uptake of anions, particularly NO3", whereas the uptake of K"^ and NH^^ was unaffected. These effects were accompanied by an increase in net H"^ release which was quantitatively comparable W'ith the reduction in NO3" uptake. The reduction in NO3" uptake and the concomitant increase in H"^ release increased with the quantity of Al accumulated in the roots, which was itself dependent on the concentration of Al in solution. The Al-sensitive cultivar bound more Al to its roots than the Al-tolerant one; the reduction in NO3ũ ptake and the increase in H"^ release were also greater in the Al-sensitive cv. Dye indicator videodensitometry show^ed that the increased H"^ release was general all along the roots.These results led us to specify the relation between the Al deposition in roots, the reduction in NO3" uptake and the stimulation in rhizosphere acidification by the plants. They show that, wdth maize, Al induces an inhibition in NO3" uptake and an increase in net H" release in a 1:1 ratio. These concomitant effects suggest that inhibition in NO3~/OH" exchange unmasks active H"^ excretion which is otherwise insensitive to Al. Both these effects are closely related to the Al content in roots expressed per unit root length.

Molecular Basis of Aluminium Toxicity in Plants: A Review

“…Both sensitive and tolerant genotypes of wheat had presented a decrease in K and Mg contents in roots, whereas Ca, Al, Si contents increased [89]. It was reported that NO 3− uptake by soybean was decreased when Al concentration in solution increased from 10 to 50 µM [90] whereas, Al reduced Cl − and NO 3− uptake in maize [91]. It is also observed that Al toxicity is closely related to nitrogen metabolism [92].…”

Influence of fire history and soil properties on plant species richness and functional diversity in a neotropical savanna

“…Exchangeable aluminum decreases nutrient availability to plants by lowering phosphorus, magnesium, and calcium absorption (Malavolta et al 1977;Marschner 1989), as well as inducing a drastic reduction in anion uptake by plant roots (Calba & Jaillard 1997). However, there is evidence of high species richness in sites where plant growth is limited by several nutrients (Braakhekke 1980;Tilman 1982; Harpole & Figure 1.…”

Arbuscular mycorrhizal fungi might alleviate aluminium toxicity in banana plants

“…As noted by Rufyikiri (2000), these changes in pH indicate that those of the input solutions are of a little importance for interpreting rhizospheric phenomena, such as nutrient uptake and element toxicity, that could be influenced by the proton activity. In this experiment, nutrient solutions were not adjusted and maintained at the same pH by the addition of acid or basic solution as in other studies (Calba & Jaillard, 1997 ;Ishikawa & Wagatsuma, 1998). However, the acidification induced by roots, especially of Al !…”