Localisation of citrulline synthesis in the alder root nodule and its implication in nitrogen fixation.

The site of citrulline synthesis in the alder root nodule symbiosis has been located cytochemically in the mitochondria of the host cell. Added to our understanding of nitrogen fixation in this symbiosis such results suggest that the host exerts a modifying influence on the nitrogen metabolism of the endophyte and is in keeping with the findings of other workers on the blue-green algal/fungal or hepatic symbiosis.