Enhanced Dark Carbon Dioxide Fixation in Maize: Effect of the Oxygen Concentration during Preillumination on 14CO2 Uptake and the Intramolecular Labeling Pattern of Malate and Aspartate

AUTOR(ES)

Creach, Elisabeth

RESUMO

The enhanced dark CO2 uptake after a preillumination period under varying O2 concentrations has been measured with maize, a C4 plant. For comparison the same study has been conducted with tomato, a C3 plant. Increasing the O2 concentration during preillumination inhibits by 70% the subsequent dark CO2 uptake in tomato but stimulates 2-fold this CO2 uptake in maize. The O2 enhancement of CO2 uptake in maize is due to the enhancement of malate and aspartate synthesis. The percentages of radioactivity incorporated in the C-4 of malate and aspartate vary from 74 to 87% when O2 concentration during preillumination is increased from 0 to 100%.

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