Department of Chemistry, The International Rice Research Institute, Los Baños, Laguna, Philippines.
Plant Physiol. 1976 Jun;57(6):923-7. doi: 10.1104/pp.57.6.923.
The effects of nitrogen source NO(3) (-) or NH(4) (+) on nitrogen metabolism during the first 2 weeks of germination of the rice seedling (Oryza sativa L., var. IR22) grown in nutrient solution containing 40 mug/ml N were studied. Total, soluble protein, and free amino N levels were higher in the NH(4) (+)-grown seedling, particularly during the 1st week of germination. Asparagine accounted for most of the difference in free amino acid level, in both the root and the shoot. Nitrate and nitrite reductase activities were present mainly in the shoot and were higher in the NO(3) (-)-grown seedling, whereas the activity of glutamate dehydrogenase and glutamine synthetase in the root tended to be lower than that of the NH(4) (+)-grown seedling during the 1st week of germination. Glycolate oxidase and catalase activities were present mainly in the shoot. Maximum activity of the above five enzymes occurred 7 to 10 days after germination. Differences in the zymograms of nitrate reductase, glutamate dehydrogenase, and catalase were mainly between shoot and root and not from N source. Nitrite reductase bands were observed only in plants grown in plants grown in NO(3) (-).Ten-day-old seedlings of three rices differing in level of grain protein did not differ in the level of N fractions and of enzyme activities, which were consistent with their differences in grain protein content.
在含有 40 微克/毫升 N 的营养液中生长的水稻幼苗（Oryza sativa L.，品种 IR22）在发芽的头两周内，研究了氮源 NO（3）（-）或 NH（4）（+）对氮代谢的影响。在 NH（4）（+）培养的幼苗中，总蛋白、可溶性蛋白和游离氨基酸 N 水平较高，尤其是在发芽的第一周。在根和芽中，天冬酰胺占游离氨基酸水平差异的大部分。硝酸盐和亚硝酸盐还原酶活性主要存在于芽中，在 NO（3）（-）培养的幼苗中较高，而谷氨酸脱氢酶和谷氨酰胺合成酶在根中的活性在发芽的第一周往往低于 NH（4）（+）培养的幼苗。乙醛酸氧化酶和过氧化氢酶活性主要存在于芽中。上述五种酶的最大活性出现在发芽后 7 至 10 天。硝酸还原酶、谷氨酸脱氢酶和过氧化氢酶的同工酶差异主要在芽和根之间，而不是氮源。仅在以 NO（3）（-）培养的植物中观察到亚硝酸还原酶带。三种稻米幼苗在发芽 10 天时，其氮素组分水平和酶活性没有差异，这与它们在籽粒蛋白质含量上的差异一致。
