Symbiotic N2-fixation under elevated CO2
The regulation of N2-fixation rates within soybean plants appears to depend on a feedback mechanism from the shoots, but the details are unresolved. Serraj and Sinclair (pp. 85-89) explore the accumulation of ureides, the products of N2-fixation in soybean, following exposure of whole plants to ambient and elevated CO2 concentrations. Results indicate that ureides do not trigger changes in N2-fixation rates directly. However, it is suggested that a product of ureide catabolism is involved in a feedback on nodule activity.
