PROLINE ACCUMULATION, NITROGENASE (C2H2 REDUCING) ACTIVITY AND ACTIVITIES OF ENZYMES RELATED TO PROLINE METABOLISM IN DROUGHT-STRESSED SOYBEAN NODULES
PROLINE ACCUMULATION, NITROGENASE (C2H2 REDUCING) ACTIVITY AND ACTIVITIES OF ENZYMES RELATED TO PROLINE METABOLISM IN DROUGHT-STRESSED SOYBEAN NODULES
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DOI：
10.1093/jxb/42.7.831
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发表时间：
1991-07-01
影响因子：
6.9
通讯作者：
SHEARER, G
中科院分区：
文献类型：
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作者：
KOHL, DH;KENNELLY, EJ;SHEARER, G
我们研究了干旱胁迫对大豆（Glycine max [L.] Merr.）根瘤中脯氨酸积累、固氮酶活性和脯氨酸代谢相关酶活性的影响。 由于干旱胁迫，固氮酶（C2H2 还原）活性被抑制 90% 或更多。 4小时恢复期后，这种抑制作用基本上被逆转。 25 日龄植物的干旱胁迫根瘤提取物中吡咯啉-5-羧酸还原酶活性比未胁迫的根瘤高 55%，但 55 日龄植物的制剂中的相同活性与对照植物相似。 两个年龄的植物上恢复根瘤的提取物的活性接近对照。 干旱胁迫使 55 日龄植物根瘤提取物中戊糖磷酸途径的活性增加约 65%，但对较年轻植物（25 日龄）根瘤提取物没有影响。 从 25 日和 55 日龄胁迫植物根瘤中分离的类菌体中，脯氨酸脱氢酶活性分别比对照对照类菌体高 3.7 倍和 1.6 倍。 在两组恢复的结节的类菌体中，这种活性仍然很高。 尽管脯氨酸脱氢酶活性增加，但受应激根瘤提取物中脯氨酸的含量比未受应激根瘤高出 3 至 4 倍，并且在重新浇水 4 小时后收集的根瘤中仍保持较高水平。 在细胞质和类菌部分中均观察到这种增加。 讨论了这些结果可能的生理意义。
We examined the effect of drought stress on proline accumulation, nitrogenase activity and activities of enzymes related to proline metabolism in soybean (Glycine max [L.] Merr.) nodules. Nitrogenase (C2H2 reducing) activity was inhibited 90% or more as a result of drought stress. This inhibition was substantially reversed after a 4 h recovery period. Pyrroline-5-carboxylate reductase activity in extracts of drought-stressed nodules from 25-d-old plants was 55% higher than in unstressed nodules, but the same activity in preparations from 55-d-old plants was similar to that of control plants. Extracts of recovering nodules on plants of both ages had activities near those of controls. Drought stress increased the activity of the pentose phosphate pathway by about 65% in extracts of nodules from 55-d-old plants, but there was no effect in extracts of nodules from younger plants (25-d-old). Proline dehydrogenase activity was 3.7 and 1.6 times higher in bacteroids isolated from nodules taken from 25- and 55-d-old stressed plants, respectively, than in comparable control bacteroids. This activity remained high in bacteroids from both sets of recovering nodules. The amount of proline in extracts from stressed nodules was 3- to 4-fold higher than in unstressed nodules, despite increased proline dehydrogenase activity and remained high in nodules collected 4 h after rewatering. This increase was observed in both cytoplasmic and bacteroid fractions. The possible physiological significance of these results is discussed.