Anion influx, ATP level and CO2 fixation in Limnophila gratioloides and Chara foetida

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Abstract
Influx of anions (5x10−4 M Cl− or SO4 2−) across the plasmalemma, ATP levels and CO2 fixation in Limnophila and Chara have been measured in a comparative study. In Limnophila, influx, ATP level and CO2 fixation were progressively reduced by increasing concentrations of carbonyl cyanide m-chlorophenylhydrazone (CCCP) in the light (4000 lux) as well as in the dark. In Chara, not only influx but also ATP levels were much less reduced in the light than in the dark. At 5x10−4 M external salt concentration the action of light or dark is to change active influx of anions. Thus this study provides strong evidence to support the view that active anion uptake is directly dependent on ATP rather than on electron flow or NADPH. The possible significance of differences in the photophosphorylation systems of various plants is stressed.