[Objective] Two purple-fleshed sweet potato cultivar and strain, ‘A5’ and ‘Yamakawamurasaki’, and one white-fleshed sweet potato cultivar ‘Yubeibai’ were used to study the role of dihydroflavonol 4-reductase (DFR) in anthocyanin accumulation of purple- fleshed sweet potato. [ Method ] Anthocyanin content, DFR activities and expression of IbDFR gene were determined respectively, while the correlation between the content of anthocyanin and DFR activities, and that between anthocyanin content and IbDFR gene expression were analyzed. [ Result ] The results showed that the activities of DFR were dramatically and positively correlated with the content of anthocyanin no matter in different organs of the same cultivar (strain) or in same organ of the same cultivar (strain) at different growth stages. Moreover, the variation trends of the relative expression of IbDFR gene also coincided with that of anthocyanin content in storage roots of different cultivars (strain) and of different developing states of ‘Yamakawamurasaki’. [Conclusion] These results indicate that DFR is a key enzyme in anthocyanin synthesis of purple- fleshed sweet potato, and the biosynthesis of anthocyanin is in situ synthesis in purple-fleshed sweet potato.%[目的]以块根着色部位和程度不同的2个紫心甘薯品种(系)'A5'和'山川紫'以及白心甘薯品种'禺北白'为试材,研究紫心甘薯二氢黄酮醇4-还原酶(DFR)基因表达及其酶活性与花色苷积累的相关性.[方法]对紫心甘薯在不同生长时期各器官(叶、茎、块根)的花色苷含量和DFR的活性进行了测定,对二者之间的变化趋势进行了相关性分析.此外,通过实时荧光定量PCR检测了'A5'、'山川紫'和‘禺北白'块根中IbDFR的表达量以及不同发育时期的山川紫块根中IbDFR的表达量,并测定了相应的花色苷含量变化.[结果]在同一生长时期的各品种(系)甘薯中,着色程度深的器官,其花色苷的含量较高,DFR活性也较高,不同器官的DFR活性与相应的花色苷含量呈显著线性正相关;在不同的生长时期,3个品种(系)甘薯各器官的花色苷含量与DFR活性的变化趋势相一致,并且呈显著线性正相关;3个品种(系)甘薯中,着色程度深的块根,其花色苷的含量较高,IbDFR的表达量也较高;在‘山川紫'块根的3个发育阶段,随着根的膨大,花色苷含量逐渐升高,IbDFR的表达量也逐渐增大.[结论]在不同生长时期的甘薯各器官中,DFR活性与花色苷含量均呈线性正相关,且紫心甘薯块根中IbBFR表达量的变化与其花色苷含量的变化趋势相一致,说明DFR是紫心甘薯花色苷合成代谢过程中的关键酶;紫心甘薯花色苷是原位合成的.
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