Leghemoglobin is an oxygen-carrying protein, somewhat similar to the hemoglobin of blood, that helps maintain the low oxygen tension necessary for effective nitrogen fixation. This is an essential component for nitrogen fixation by legumes. Leghemoglobin is produced as a result of symbiotic association between bacteroid and plant. The major role of leghemoglobin involves protection of nitrogenase enzyme from denaturation, if exposed to atmospheric concentration of oxygen, but at the same time supply of ample amount of oxygen to bacteria for respiration.