在低氮胁迫下,以黄瓜品种津研4号叶片为供试材料,以cDNA为模板,依据黄瓜基因组数据库中Csa002986基因编码区全序列,应用Primer Premier 5.0软件设计引物,克隆得到黄瓜钙依赖蛋白激酶基因(calcium-dependent protein kinase,CDPK)。该基因全长1584bp,编码527个氨基酸。预测该基因编码的蛋白是一个稳定的亲水蛋白,无跨膜结构,无信号肽,存在蛋白激酶结合区、EF手型钙结合区、丝氨酸/苏氨酸蛋白激酶活性位点、N酰基化位点等多个位点。CDPK基因在不同氮浓度处理下黄瓜各部位表达分析结果显示,在无氮条件下,CDPK基因在茎尖表达量最高,其次为叶和茎;在低氮条件下,CDPK基因在茎中表达量最高,其次为茎尖和叶;在正常及高氮条件下,CDPK基因在茎尖表达量最高,其次为茎和叶。CDPK基因在叶中的表达模式分析结果显示,在无氮及低氮胁迫下CDPK基因表达量增加,随着氮浓度的降低,CDPK基因的表达量增加并明显高于对照;在高氮胁迫条件下,CDPK基因的表达量低于对照。
The sucrose non-fermenting-1 related protein kinase（SnRK）, whose expression is induced by kinds of hyperosmotic stresses, plays a key role in improving stress resistance of plants. In order to investigate the molecular mechanism of low nitrogen resistance in cucumber, the full-length cDNA of SnRK gene was cloned in this study. The result showed that SnRK gene was 1 548 bp in length, encoded 515 amino acids, and had more than 80% homology with other crops. The protein encoded by this gene was an unstable and hydrophilic protein with no transmembrane structure and no signal peptide. Under nitrogen-free conditions and low nitrogen conditions, the expression pattern analysis of SnRK gene showed that this gene was up-regulated and its expression increased and was significantly higher than the normal level as the nitrogen concentration decreased. In addition, the expression of SnRK gene was also inhibited in the high nitrogen level and was significantly lower than the normal level. The result of this study would help us understand the molecular mechanism of low nitrogen resistance in cucumber.
