FLUORIDE METABOLISM IN ACACIA GEORGINAE GIDYEA

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Abstract
The metabolism of fluoride in seedlings and small plants of A. georginae was studied with the idea of finding the conditions under which the plant makes fluoroacetate in the laboratory. Individual seedlings varied in the extent to which they took up fluoride and converted it into a form other than inorganic which is here called "organic" fluoride. The differences between the toxicity of A. georginae trees, therefore, may be genetic in origin. The uptake of fluoride from solutions 0. 525-1.05m[image] (10-20ppm) was not large. In 1-4 days it reached 8ppm in the aerial parts and 16ppm in the roots. Unlike the distribution of the halogen in grass, total fluoride was greater than inorganic fluoride. It was almost a rule that more "organic" fluoride was present in the roots than in the aerial parts. With higher concentrations of fluoride, 10. 5-15. 75m[image] (200-300ppm), much larger amounts of fluoride were taken up, especially by the roots, and much more apparent organic fluoride was formed. pH had a great influence upon the intake, this being lowest at an initial pH 8. 4 and highest at pH4. 0. The pH outside this range was not investigated. Some observations were made with a view to clarifying the biochemical paths for the synthesis of the C-F bond. There was no evidence that chloride is an intermediary in synthesis. Succinate did not accumulate in fluoride-stressed plants, suggesting that succinate dehydrogenase is not inhibited. Enolase did not appear to be inhibited in vivo.