Effects of nitrogen supply level on the membrane lipids and fatty acid content of leaves in broccoli | 氮营养水平对青花菜叶片膜脂组成和脂肪酸含量的影响

Chinese. 采用无机基质盆栽，研究不同氮浓度水平（5、10、15和20mmol・L. 1）对青花菜叶片膜脂含量和脂肪酸组成的影响。结果表明，青花菜叶片含有单半乳糖甘油二酯（MGDG）、双半乳糖甘油二酯（DGDG）、磷脂酰甘油（PG）、硫代异鼠李糖甘油二酯（SQDG）、磷脂酰胆碱（PC）和磷脂酰乙醇胺（PE）6种膜脂，同时检测出7种主要脂肪酸（C16：0、C16：2、C16：3、C18：0、C18：1、C18：2和C18：3）。MGDG和PC相对含量随氮浓度增加呈先升高后降低的变化趋势，并在氮浓度为15mmol・L. 1时达到最高；而DGDG相对含量却随氮浓度增加而显著降低。当氮浓度为20mmol・L. 1时，有利于PG和SQDG相对含量的提高，却显著降低了PE相对含量。增加氮浓度，有利于青花菜叶片总脂肪酸的积累，同时提高C16：0、C16：2和C18：3的相对含量。通过单膜脂的脂肪酸分析发现，MGDG中不饱和脂肪酸含量最高，其中C18：3和C16：3为主要组分，增加氮浓度有利于MGDG中不饱和与饱和脂肪酸的比例提高。因此适度增加氮浓度水平有利于青花菜叶片中膜脂MGDG、PG、SQDG和PC的合成及不饱和脂肪酸的积累，从而有利于叶片的光合作用及对环境适应能力的提高。[著者文摘]

English. Medium culture experiments were carried out to study effects of nitrogen levels （5, 10, 15 and 20 mmol.L. 1 ） on the membrane lipids composition and fatty acid content in leaves of broccoli （ Brassica oleracea L. var. italica. Plenck）. The results showed that the major membrane lipids in leaves of broccoli were the monogalactosyldiacylglycerol （MGDG） , digalactosyldiacylglycerol （DGDG）, phosphatidylglycerol （PG）, sulfoquinovosyldiacylglycerol （SQDG）, phosphatidylcholine （PC） and phosphatidylethanolamine （PE）. The palmitic （C16： 0） , hexadecadienoic （ C16： 2） , hexadecatrienoic （ C16： 3） , stearic （ C18： 0） , oleic （ C18：1 ）, linoleic （ C18：2 ）, and linolenic （ C18 ： 3 ） acids were major fatty acids. The relative contents of MGDG and PC significantly increased with the increase of nitrogen supply, reached the highest value when nitrogen concentration was 15 mmol. L. 1, and then gradually decreased; however, increasing nitrogen supply resulted in decrease of DGDG. When nitrogen concentration increased up to 20 mmol.L. 1, the relative contents of PG and SQDG were significantly improved, but PE was decreaesd. Nitrogen application significantly increased total fatty acid, C16： 0, C16：2 and C18：3 contents. In addition, MGDG had the highest ratio of unsaturated to saturated fatty acids among all membrane lipids, which was very rich in C18：3 and C16： 3. There was a significant increase in the content of unsaturation fatty acids in MGDG with the increase of nitrogen supply. These resuits suggested that appropriately increasing nitrogen supply was beneficial to membrane lipids biosynthesis and the accumulation of unsaturation fatty acids, and further promoted the membrane integrity and photosynthesis in leaves of broccoli.