Klucas R V, Arp D
Can J Microbiol. 1977 Oct;23(10):1426-32. doi: 10.1139/m77-211.
Senescence of soybean (Glycine max L. Merr.) tap root nodules was investigated by comparing changes in various physiological and biochemical activities with changes in capacity to fix nitrogen. Field-grown Beeson and Calland varieties of soybeans of various ages were sources of tap root nodules. With both varieties, the number of tap root nodules per plant remained constant between 56 and 86 days after planting but fresh weight, dry weight, and mass of tap root nodules increased duing this period. Nitrogen (C2H2)fixation by attached tap root nodules was maximum on a fresh weight, dry weight, or nitrogen basis about 56 days after planting for either variety. Metabolic activities of bacteroids as measured by carbon dioxide evolution from glucose and succinate did not appear to vary among nodules of different ages. There was also no indication of mobilization or deposition or deposition of iron, molybdenum, calcium, zinc, and nitrate in aging tap root nodules. Nitrate levels in the aerial portion of the plants decreased significantly after the initial decline in acetylene reduction. Nicotinamide deamidase activity in the cytosol and in extracts of bacteroids did not change significantly as tap root nodules aged. However, significant and consistent changes were observed in initial pH values of nodule breis and the initial decline occurred before (Calland) or concurrently (Beeson) with the initial decline of nitrogen fixation.
通过比较各种生理生化活性的变化与固氮能力的变化，对大豆（Glycine max L. Merr.）主根根瘤的衰老进行了研究。田间种植的不同年龄的Beeson和Calland品种大豆是主根根瘤的来源。对于这两个品种，每株植物的主根根瘤数量在种植后56至86天之间保持恒定，但在此期间主根根瘤的鲜重、干重和质量增加。对于任一品种，附着的主根根瘤在种植后约56天，以鲜重、干重或氮为基础的固氮（C2H2）量最大。通过葡萄糖和琥珀酸释放二氧化碳来衡量的类菌体代谢活性在不同年龄的根瘤中似乎没有变化。在衰老的主根根瘤中也没有铁、钼、钙、锌和硝酸盐的动员或沉积的迹象。在乙炔还原最初下降后，植株地上部分的硝酸盐水平显著降低。随着主根根瘤的衰老，胞质溶胶和类菌体提取物中的烟酰胺脱氨酶活性没有显著变化。然而，在根瘤匀浆的初始pH值中观察到了显著且一致的变化，初始下降在固氮初始下降之前（Calland）或同时（Beeson）发生。
