不结球白菜硝酸还原酶基因cDNA的克隆及序列分析

Cloning and sequence analysis of nitrate reductase gene cDNA fragments from non-heading Chinese cabbage

采用离体法测定了经50 mmol.L-1的KNO3诱导不同时间后的雪克青、苏州青、矮脚黄、乌塌菜(黄心乌)4个不结球白菜品种叶片硝酸还原酶的活性。结果表明,4个品种的硝酸还原酶活性变化趋势相似,且分别在4、4、6、6 h达到最高峰。苏州青经50 mmol.L-1的KNO3诱导4 h后,提取其叶片总RNA,用RT-PCR方法获得硝酸还原酶基因cDNA的2条片段,长度为1 125 bp和438 bp,分别编码374个和135个氨基酸,命名为nr1125和nr438。nr1125在GenBank的登录号为DQ001901。

The experiment was conducted to investigate the activity of nitrate reductase （NRA） in leaf of non-heading Chinese cabbage. The NRA of four cultivars leaves were determined in vitro after inducing by 50mmol·L^-1 KNO3 solution. The results showed that the change trends of these four cultivars were similar. The highest NRA in leaves of these four cuhivars reached to maximum at 4, 4, 6, 6 h, respectively. According to these results, the level of nitrate reductase （NR） mRNA in plants could be enhanced by nitrate inducement. The total RNA isolated from leaves of Suzhouqing was induced by 50mmol·L^-1 KNO3 solution for 4 h, and two fragments of NR cDNA was obtained through RT-PCR using specific primers. The products of PCR were cloned and sequenced. They are 1 125 and 438 base pairs, which named nr1125 and nr43s, encoding 374 and 135 amino acids respectively. As a result, nr1125 was accepted and released by GenBank （accession number DQ001901 ）.