摘    要蚕白作为一种蔬菜不仅能给人类提供维生素、矿物质等一些重要的营养成分，同时还具有抗氧化的功能，其抗氧化活性对于预防癌症、心血管疾病以及抗衰老等具有重要的功能。研究报道表明，黄酮等是植物体内重要的抗氧化活性物质。由于黄酮等天然抗氧化活性物质大多为植物次生代谢产物，其本身并不直接参与植物的生长、发育过程，植物在正常生长条件下并不需要大量合成此类物质，因此这类物质在植物体中的含量往往比较低。前期研究表明，干旱、高温、机械损伤、病虫害等生物和非生物逆境胁迫可以显著诱导植物体内黄酮类物质的合成积累。因此，理论上利用温和的逆境因子处理可以提高蔬菜体内黄酮含量及抗氧化活性。UV-B是一种短波长紫外光，也是一种常见的植物生长逆境因子。本文以人工温室生长的蚕白为材料，以DPPH清除率、羟基自由基清除率及总还原能力为指标，系统考查了不同强度UV-B处理对蚕白抗氧化活性及黄酮含量的影响；并且利用定量PCR技术分析了UV-B处理对蚕白黄酮生物合成途径关键酶基因表达水平的影响。结果表明，在本文实验条件下，4 µmol·m-2·s-1 UV-B处理4 h对蚕白抗氧化活性及黄酮含量具有显著的促进作用。进一步分析发现，UV-B可以显著上调BrCHS、BrPAL、BrC4H、BrCHI、Br4CL等黄酮生物合成途径关键酶基因表达。实验结果同时表明，4 µmol·m-2·s-1 UV-B处理4 h对蚕白的单株鲜重和干重无影响影响。综上所述，本文试验结果表明，适量的UV-B处理可以在不影响蚕白生长的情况下通过激活黄酮生物合成途径促进黄酮类物质合成积累，提高蚕白抗氧化活性。研究结果为生产实践中提高蔬菜抗氧化活性提供了一种新的策略。89790

Abstract Can Bai as a vegetable can not only provide humans with vitamins, minerals and other important nutrients, but also has the function of antioxidant, the antioxidant activity for the prevention of cancer, cardiovascular disease and anti-aging has important function。 Studies have shown that flavonoids are important antioxidant substances in plants。 Natural antioxidants in plants for the majority of secondary metabolites, which itself is not directly involved in plant growth, development process, plants do not need a lot of synthesis of these compounds in normal growth conditions, so the content of this kind of material in plants are relatively low。 Previous studies have shown that drought, high temperature, mechanical damage, insect pests and other abiotic and biotic stress can significantly induce the synthesis and accumulation of flavonoids in plants。 Therefore, in theory, the use of mild stress factor can improve the flavonoids content and antioxidant activity。 UV-B is a kind of short wavelength ultraviolet light, which is also a common plant growth stress factor。 In this paper, the growth of artificial greenhouse Can Bai as material, the clearance rate of DPPH, the scavenging rate of hydroxyl radical and total reducing capacity were taken as indexes, the effect of UV-B treatment on antioxidant activity and flavonoids content of Can Bai was investigated, and quantitative PCR was used to analyze the effect of UV-B treatment on the expression of key enzymes in the biosynthetic pathway of flavonoids in Can Bai。 The results show that under the experimental conditions in this paper, 4 µmol·m-2·s-1 UV-B 4 h of the Can Bai antioxidant activity and flavonoids content has significant effect。 Further analysis showed that UV-B could significantly up regulate the expression of BrCHS, BrPAL, BrC4H, BrCHI, and Br4CL in the biosynthetic pathway of flavonoids。 The experimental results also show that the 4 µmol·m-2·s-1 UV-B treatment 4h on Can Bai plant fresh weight and dry weight had no effect。 In summary, the results of this study showed that the proper amount of UV-B treatment could promote the synthesis and accumulation of flavonoids and enhance the antioxidant activity of Can Bai through the activation of flavonoid biosynthesis pathway and does not affect the growth of Can Bai。 The results provide a new strategy for improving the antioxidant activity of vegetables。