Relationships between Carbon Dioxide, Malate, and Nitrate Accumulation and Reduction in Corn (Zea mays L.) Seedlings 1

AUTOR(ES)

Neyra, Carlos A.

RESUMO

The observation that exposure of the leaf canopy to increasing concentrations of CO2 (100-400 μl/l) decreases the influx of nitrate to the leaf blades, but not to the roots or stalks (largely leaf sheaths), was reconfirmed using 15NO3−. Decreases in leaf nitrate supply were associated with decreases in induction of nitrate reductase, thus supporting the view that the influx of nitrate to a tissue is a major factor in regulation of the level of nitrate reductase. The whole plant 15N distribution data show that the CO2 effects were due to decreased influx of nitrate into the leaf blade rather than CO2-enhanced nitrate reduction. The decreases in nitrate accumulation by the leaf blade with increases in CO2 concentration were only partially accounted for by differences in transpiration. Because the initial malate concentration of root tissue (detopped plants) had no subsequent effect on nitrate uptake, it seems unlikely that high levels of malate induced by CO2 were responsible for the exclusion of nitrate from the leaf blades.

Documentos Relacionados

• Nitrate Reduction in Roots and Shoots of Barley (Hordeum vulgare L.) and Corn (Zea mays L.) Seedlings: I. 15N Study
• Nitrate Reductase Activity and Polyribosomal Content of Corn (Zea mays L.) Having Low Leaf Water Potentials 1
• Relationship between Nitrate Uptake, Flux, and Reduction and the Accumulation of Reduced Nitrogen in Maize (Zea mays L.): I. GENOTYPIC VARIATION 1
• Effect of Carbon Dioxide on Nitrate Accumulation and Nitrate Reductase Induction in Corn Seedlings 1
• Relationship between Nitrate Uptake, Flux, and Reduction and the Accumulation of Reduced Nitrogen in Maize (Zea mays L.): II. EFFECT OF NUTRIENT NITRATE CONCENTRATION 1