Key message

The transcription factor (TF) IbERF71 forms a novel complex, IbERF71-IbMYB340-IbbHLH2, to coregulate anthocyanin biosynthesis by binding to the IbANS1 promoter in purple-fleshed sweet potatoes.

Abstract

Purple-fleshed sweet potato (Ipomoea batatas L.) is very popular because of its abundant anthocyanins, which are natural pigments with multiple physiological functions. TFs involved in regulating anthocyanin biosynthesis have been identified in many plants. However, the molecular mechanism of anthocyanin biosynthesis in purple-fleshed sweet potatoes has rarely been examined. In this study, TF IbERF71 and its partners were screened by bioinformatics and RT-qPCR analysis. The results showed that the expression levels of IbERF71 and partners IbMYB340 and IbbHLH2 were higher in purple-fleshed sweet potatoes than in other colors and that the expression levels positively correlated with anthocyanin contents. Moreover, transient expression assays showed that cotransformation of IbMYB340+IbbHLH2 resulted in anthocyanin accumulation in tobacco leaves and strawberry receptacles, and additional IbERF71 significantly increased visual aspects. Furthermore, the combination of the three TFs significantly increased the expression levels of FvANS and FvGST, which are involved in anthocyanin biosynthesis and transport of strawberry receptacles. The dual-luciferase reporter system verified that cotransformation of the three TFs enhanced the transcription activity of IbANS1. In addition, yeast two-hybrid and firefly luciferase complementation assays revealed that IbMYB340 interacted with IbbHLH2 and IbERF71 but IbERF71 could not interact with IbbHLH2 in vitro. In summary, our findings provide novel evidence that IbERF71 and IbMYB340-IbbHLH2 form the regulatory complex IbERF71-IbMYB340-IbbHLH2 that coregulates anthocyanin accumulation by binding to the IbANS1 promoter in purple-fleshed sweet potatoes. Thus, the present study provides a new regulatory network of anthocyanin biosynthesis and strong insight into the color development of purple-fleshed sweet potatoes.

中文翻译：

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IbERF71 与 IbMYB340 和 IbbHLH2 通过与紫肉甘薯 ( Ipomoea batatas L.) 中的 IbANS1 启动子结合来共同调节花青素的积累

关键信息

转录因子 (TF) IbERF71形成一种新型复合物IbERF71-IbMYB340-IbbHLH2 ，通过与紫肉红薯中的IbANS1启动子结合来共同调节花青素的生物合成。

抽象的

紫肉甘薯（Ipomoea batatas L.）因其丰富的花青素而广受欢迎，花青素是具有多种生理功能的天然色素。已在许多植物中鉴定出参与调节花青素生物合成的 TF。然而，很少有人研究紫肉红薯中花青素生物合成的分子机制。在本研究中，通过生物信息学和 RT-qPCR 分析筛选了 TF IbERF71及其伙伴。结果显示IbERF71及其伴侣IbMYB340和IbbHLH2的表达水平紫肉红薯中的表达量高于其他颜色，并且表达水平与花青素含量呈正相关。此外，瞬时表达分析表明，IbMYB340+IbbHLH2的共转化导致花青素在烟叶和草莓容器中积累，并且额外的 IbERF71显着增加了视觉方面。此外，三种 TF 的组合显着增加了FvANS和FvGST的表达水平，它们参与了花青素的生物合成和草莓容器的运输。双荧光素酶报告系统验证了三个 TF 的共转化增强了IbANS1 的转录活性。此外，酵母双杂交和萤火虫荧光素酶互补测定显示，IbMYB340 与 IbbHLH2 和 IbERF71 相互作用，但 IbERF71 在体外不能与 IbbHLH2 相互作用。总之，我们的研究结果提供了新的证据，证明 IbERF71 和 IbMYB340-IbbHLH2 形成调节复合物 IbERF71-IbMYB340-IbbHLH2，通过与紫肉红薯中的IbANS1启动子结合来共同调节花青素的积累。因此，本研究提供了一个新的花青素生物合成调控网络，并深入了解了紫肉红薯的颜色发展。