Metabolic fractionation of C¹³ & C¹² in plants

Abstract

C/sup 13//C/sup 12/ ratio analyses of chemical fractions from several plant phyla show that in all cases the lipid fraction is enriched in C/sup 12/ compared to the whole plant. The C/sup 13//C/sup 12/ r atio of the plant lipids corresponds roughly to the C/sup 13//C/sup 12/ ratio of petroleums. The C/sup 12/ enrichment in petroleums a compared to present day plants can be explained if selective preservation of plant lipids occurred during the sedimentation process. The degree of C/sup 12/ enrichment in the plant lipid fraction is inversely related to the amount of lipid in the plant. The C/sup 12/ enrichment which occurs in plant lipids may be balanced by the C/sup 13/ enrichment which occurs in respired CO/sub 2/. Isotope selection at the level of acetate or pyruvate is a possible mechanism for explaining our results. (auth)