Hemoglobin in a Nonleguminous Plant, Parasponia: Possible Genetic Origin and Function in Nitrogen Fixation

Science  27 May 1983:
Vol. 220, Issue 4600, pp. 951-953
DOI: 10.1126/science.220.4600.951


A dimeric hemoglobin was purified from nitrogen-fixing root nodules formed by association of Rhizobium with a nonleguminous plant, Parasponia. The oxygen dissociation rate constant is probably sufficiently high to allow Parasponia hemoglobin to function in a fashion similar to that of leghemoglobin, by oxygen buffering and transport during symbiotic nitrogen fixation. The identification of hemoglobin in a nonlegume raises important questions about the evolution of plant hemoglobin genes.