中文摘要：

为了明确缺氮条件下甜菜NR的活性，用活体测定法检测了经缺氮胁迫不同时间后甜菜叶中NR活性．结果表明，随着缺氮处理时间的延长，甜菜叶中的NR活性逐渐降低，在缺氯处理1h后，其活性下降较快．用50mmol／1．KNO3溶液处理的甜菜幼苗总RNA，通过RT—PCR分离得到了硝酸还原酶基因片段，长度为471bp，Blast分析表明，其与Genbank中硝酸还原酶基因部分序列具有高度同源性．

英文摘要：

The experiments are conducted to investigate the activity of nitrate reductase in sugar beet （Beta vulgaris L. ） under different time of N - absent treatment. The results show that the activity of NR rapidly decrease in the first 1 h and gradually decrease when the time of N - absent treatment is prolonged. The homolog cDNA with 471 base pairs of nitrate reduetase gene is obtained by RT - PCR from total RNA using Beta vulgaris treated by 50 mmoL/L KNO3 as material. Blast analysis showed high identity to part sequence of Beta vulgaris nitrate reductase gene.