烟草HQT基因超量表达对次生代谢物质一咖啡酰奎尼酸和黄酮醇合成的影响

  背景和目的  一咖啡酰奎尼酸（CQAs）和黄酮醇是植物重要的苯丙烷类次生代谢物质，对人体健康有益，然而在烟叶中含量甚微。  方法  NtHQT是烟草中调控一咖啡酰奎尼酸合成最后一步的一种酰基转移酶，为验证NtHQT是否参与黄酮醇的合成，本研究构建了pCXSN::NtHQT超量表达载体，转化野生烟草三生烟。  结果  转基因烟叶中一咖啡酰奎尼酸的含量最高可提高10.34倍，芦丁和山奈酚芸香糖苷含量最高可分别提高17.83和16.97倍，而生长表型与野生型烟草没有明显差异。  结论  NtHQT基因在不影响烟草的生长发育的前提下，不仅参与调控一咖啡酰奎尼酸的合成，也具有正向调控黄酮醇的生物合成的功能，提高烟叶中芦丁和山奈酚芸香糖苷含量。 

Effect of over-expression of NtHQT on synthesis of caffeoyl quinic acids and flavonols in tobacco

  Background  Caffeoyl quinic acids (CQAs) and flavonols, two of important secondary metabolites of phenylpropanoids in plant, have been proved good for human health. However, there is only a minute amount of CQAs and flavonols in tobacco leaves.  Methods  NtHQT is an acyltransferase in tobacco that regulates the final step in the synthesis of CQAs. In order to investigate whether NtHQT has participated in synthesis of flavonols, we constructed the vetor pCXSN: : NtHQT and introduced it into Nicotiana tabacum var. samsun.  Results  The concentrations of individual phenylpropanoids were increased to varying extents in NtHQT-overexpressing transgenic tobacco plants compared to wild-type plants. The concentration of CQAs was increased by 10.34-fold as maximum; and the concentrations rutin and kaempferol rutinoside were increased by 17.83- and 16.97-fold as maximum, respectively. However, the transgenic tobacco exhibited no significant differences from wild-type tobacco.  Conclusion  These results suggested NtHQT can positively regulate the synthesis of flavonols and CQAs, without affecting the growth and development of tobacco.