Mohanty B, Fletcher J S
Department of Botany and Microbiology, The University of Oklahoma, Norman, Oklahoma 73069.
Plant Physiol. 1976 Aug;58(2):152-5. doi: 10.1104/pp.58.2.152.
Suspension cultures of Paul's Scarlet rose were grown in two defined media which differed only in their inorganic nitrogen content. Both possessed equal amounts of NO(3) (+) (24 mm), but differed in that NH(4) (+) (0.91 mm) was present in control medium; whereas, no NH(4) (+) was present in the test medium. A comparison of fresh weight increases over a 14-day growth period showed that NH(4) (+) caused a 2-fold stimulation in growth and governed the pattern of development.Ammonium also caused a 2-fold increase in nitrate reductase activity but had little influence on the activity of representative enzymes from the Embden-Meyerhof pathway or citric acid cycle. Thus NH(4) (+) enhanced the nitrate reductase activity which was correlated with increased growth.Ammonium had no influence on the in vitro activity of nitrate reductase which suggested that the stimulatory influence was due to an increased synthesis of the enzyme. The enhanced synthesis did not appear to be due to an increased availability of NO(3) (+) since the uptake of NO(3) (+) by intact cells was not influenced by the presence of NH(4) (+) during the period of most rapid increase in nitrate reductase activity.
保罗猩红玫瑰的悬浮培养物在两种特定培养基中生长，这两种培养基仅在无机氮含量上有所不同。两者都含有等量的NO(3) (+)（24 mM），但不同的是对照培养基中存在NH(4) (+)（0.91 mM）；而测试培养基中不存在NH(4) (+)。对14天生长周期内鲜重增加的比较表明，NH(4) (+)使生长受到2倍的刺激并控制了发育模式。铵还使硝酸还原酶活性增加了2倍，但对来自糖酵解途径或柠檬酸循环的代表性酶的活性影响很小。因此，NH(4) (+)增强了与生长增加相关的硝酸还原酶活性。铵对硝酸还原酶的体外活性没有影响，这表明刺激作用是由于该酶合成增加所致。合成的增强似乎不是由于NO(3) (+)可用性的增加，因为在硝酸还原酶活性增加最快的时期，完整细胞对NO(3) (+)的吸收不受NH(4) (+)存在的影响。
