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为进一步揭示硝酸还原酶(nitrate reductase,NR)活性的调控机制及其与植株体内硝酸盐含量的关系。本试验在正常供氮(15 mmol L~(–1)NO_3~–)和缺氮(7.5 mmol L~(–1)NO_3~–)条件下,以氮高效(H1:742和H2:Xiangyou 15)和氮低效(L1:814和L2:H8)油菜基因型为研究材料,通过NR活性的专性抑制剂处理,研究NR活性和硝酸盐含量的基因型和氮水平差异。结果表明,NR专性抑制剂处理可以显著降低叶片NR活性,正常供氮和缺氮条件下分别降低53.0%和57.6%,但对叶片硝酸盐的含量没有显著影响。正常供氮条件下的NR活性和硝酸盐含量比缺氮条件下分别高46.9%和16.4%。氮高效油菜基因型的硝酸盐含量显著低于氮低效基因型。H2的NR活性(NRA_(act))显著高于氮低效基因型的本质原因是其主效基因(nia2)的相对表达量高于氮低效基因型。本研究充分表明NR活性和硝酸盐含量存在明显的基因型和氮水平差异,一定程度的NR活性变化对植株体内硝酸盐的含量并没有显著的影响。
In order to further reveal the regulation mechanism of nitrate reductase (NR) activity and its relationship with nitrate content in plants. In this study, nitrogen-efficient (H1: 742 and H2: Xiangyou 15) plants were treated under nitrogen (15 mmol L -1 NO 3 -) and nitrogen deficiency (7.5 mmol L -1 NO 3 - ) And nitrogen inefficient (L1: 814 and L2: H8) rapeseed genotypes were used as materials to study the difference in genotype and nitrogen levels of NR activity and nitrate content through specific inhibitors of NR activity. The results showed that NR inhibitor could significantly reduce the activity of NR, and decreased 53.0% and 57.6% under normal nitrogen supply and nitrogen deficiency, respectively, but had no significant effect on the leaf nitrate content. Under normal nitrogen supply, NR activity and nitrate content were 46.9% and 16.4% higher than those under nitrogen deficiency condition respectively. The nitrate content of nitrogen efficient rape genotypes was significantly lower than that of nitrogen inefficient genotypes. The essential reason why H2 NR activity (NRA act) was significantly higher than nitrogen inefficient genotypes was that the relative expression level of nia2 was higher than that of nitrogen inefficient genotypes. This study fully demonstrated that NR activity and nitrate content had obvious differences in genotype and nitrogen levels. To a certain extent, the changes of NR activity had no significant effect on nitrate content in plants.