氮素对不同类型玉米蛋白质及其组分和相关酶活性的影响

以普通玉米掖单22和高油含量玉米高油115为材料,测定了不同供氮水平下子粒蛋白质含量及其组分以及叶片和子粒中硝酸还原酶(NRase)、谷氨酰胺合成酶(GS)和谷氨酸脱氢酶(GDH)活性的品种差异。结果表明,玉米子粒蛋白质及其组分含量,均为高油115显著高于掖单22,其中醇溶蛋白和白蛋白含量增幅明显,且随施氮量的增加而提高。不同供氮条件下,两种类型玉米叶片中NRase、GS活性和子粒中GS、GDH活性的动态变化一致,NRase活性自灌浆初期至成熟期一直下降,GS、GDH活性呈单峰曲线,在授粉后20～30d达到高峰;增施氮肥有利于酶的活性维持较高水平。掖单22叶片中NRase活性高于高油115;叶片GS和子粒GDH活性显著低于高油115,这可能是其蛋白质含量较低的生理原因之一。

Effects of nitrogen on the protein, protein constituents and relevant enzymes activity of maize

The amount of N in soil had a direct influence on the protein content in the maize. Application of N coordinated with other nutrients (such as P, K, Mg) could not only increase the grain yield, but also the protein and lysine content. The activities of nitrate reductase (NRase), glutamine synthetase(GS), and glutamate dehydrogenase(GDH) in the leaves and grain of maize were close related to protein synthesis in kernel. However, few studies were carried out on the effect of N application on the quality constituents (protein and its constituents, amino acid, fat and its constituents) of maize. In order to learn the dynamic change of protein, its constituents and activities of relevant enzymes in the grain formation process, a pot culture experiment was carried out. Two types of maize (Zea mays) cultivars with different oil content (Yedan 22, a common cultivars and Gaoyou 115 with high oil content) were selected as experimental materials. The results showed that the content of grain protein and its constituent of Gaoyou115 were significantly higher than that of Yedan22. Among which, albumin and gliadin content, which was significant higher than those of Yedan22, increased with the increment of N supply . Under different conditions of nitrogen supply,the activities of NRase,GS in leaves and GS,GDH in grain of both cultivars took on a same tendency. The activity of NRase decreased all the time from prophase of grain filling stage to mature stage, while the activities of GS and GDH took on a singlet curves,with the peak appearing between 20 days and 30 days after pollination. Increasing the supply of N was favorable to maintaining the activities of these enzymes at high level. Comparing with Gaoyou115, The activity of NRase in leaves of Yedan22 was higher,while the activities of GS in leaves and GDH in grain was significant lower. This could results in a lower protein content in grain of Yedan22 comparing with Gaoyou115.