Bisseling T, van den Bos R C, van Kammen A
Biochim Biophys Acta. 1978 Feb 13;539(1):1-11. doi: 10.1016/0304-4165(78)90115-0.
The effects of NH4NO3 on the development of root nodules of Pisum sativum after infection with Rhizobium leguminosarum (strain PRE) and on the nitrogenase activity of the bacteroids in the nodule tissue were studied. The addition of NH4NO3 decreased the nitrogenase activity measured on intact nodules. This reduction of nitrogen fixation did not result from a reduced number of bacteroids or a decreased amount of bacteroid proteins per gram of nodule. The synthesis of nitrogenase, measured as the relative amount of incorporation of [35S]sulfate into the components I and II of nitrogenase was similarly not affected. The addition of NH4NO3 decreased the amount of leghemoglobin in the nodules and there was a quantitative correlation between the leghemoglobin content and the nitrogen-fixing capacity of the nodules. The conclusion is that the decrease of nitrogen-fixing capacity is caused by a decrease of the leghemoglobin content of the root nodules and not by repression of the nitrogenase synthesis.
研究了硝酸铵对豌豆被豌豆根瘤菌（菌株PRE）感染后根瘤发育以及根瘤组织中类菌体固氮酶活性的影响。添加硝酸铵降低了完整根瘤上测得的固氮酶活性。这种固氮作用的降低并非源于类菌体数量的减少或每克根瘤中类菌体蛋白量的减少。以[35S]硫酸盐掺入固氮酶组分I和II的相对量来衡量的固氮酶合成同样未受影响。添加硝酸铵降低了根瘤中豆血红蛋白的含量，并且豆血红蛋白含量与根瘤固氮能力之间存在定量相关性。结论是固氮能力的降低是由根瘤中豆血红蛋白含量的减少引起的，而非固氮酶合成的抑制。
