α‐Aminoadipic Acid and α,ɛ‐Diaminopimelic Acid in Inoculated Pea Plants ( Pisum sativum ) and Root Nodule Bacteria ( Rhizobium leguminosarum )

Observations were made on the content of α‐aminoadipic acid and α‐aminophimelic acid (DAP) in pea plants, nodules and Rhizobium leguminosarum , strain HT3. The preparations were purified by ion exchange chromatography, Qualitative analyses were made by paper chromatography, and quantitative analyses by means of an automatic amino acid analysator. In the whole plant and seeds the content of α‐aminoadipic acid soluble in 70% ethanol varied between 10 and 80 μg/g dry weight. The shoot and red nitrogen fixing nodules contained more of this acid than roots and green inactive nodules. In the insoluble fraction of the shoot its concentration was 0.4–0.6 mg/g dry weight. α‐Aminoadipic acid was not found in free living rhizobia, which again contained a considerable amount of α‐aiaminopimelic acid, about 0.5 mg/g dry weight. The synthesis of DAP was intensive also in root nodules. In red nodules, which fixed molecular nitrogen, the content of DAP was 2.1 mg/g dry weight and in green inactive nodules 1.3 mg/g dry weight. It was shown that in the nodules DAP is closely connected with cell wall peptides of bacteroids. DAP could not be found in pea plants outside the nodules.