Anthocyanin Accumulation in the Leaves of the Purple Sweet Potato (<i>Ipomoea batatas</i> L.) Cultivars

• Main Authors: GuoLiang Li, Zhaomiao Lin, Hong Zhang, Zhonghua Liu, Yongqing Xu, Guochun Xu, Huawei Li, Rongchang Ji, Wenbin Luo, Yongxiang Qiu, Sixin Qiu, Hao Tang
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Molecules
• Subjects: sweet potato; anthocyanin compositions; biosynthesis structural genes; transcription factor
• Online Access: https://www.mdpi.com/1420-3049/24/20/3743

Sweet potato anthocyanins are water-soluble pigments with many physiological functions. Previous research on anthocyanin accumulation in sweet potato has focused on the roots, but the accumulation progress in the leaves is still unclear. Two purple sweet potato cultivars (Fushu No. 23 and Fushu No. 317) with large quantities of anthocyanin in the leaves were investigated. Anthocyanin composition and content were assessed with ultra-performance liquid chromatography diode-array detection (UPLC-DAD) and ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS), and the expressions of genes were detected by qRT-PCR. The two cultivars contained nine cyanidin anthocyanins and nine peonidin anthocyanins with an acylation modification. The acylation modification of anthocyanins in sweet potato leaves primarily included caffeoyl, <i>p</i>-coumaryl, feruloyl, and <i>p</i>-hydroxy benzoyl. We identified three anthocyanin compounds in sweet potato leaves for the first time: cyanidin 3-<i>p</i>-coumarylsophoroside-5-glucoside, peonidin 3-<i>p</i>-coumarylsophoroside-5-glucoside, and cyanidin 3-caffeoyl-<i>p</i>-coumarylsophoroside-5-glucoside. The anthocyanidin biosynthesis downstream structural genes <i>DFR4</i>, <i>F3H1</i>, anthocyanin synthase (<i>ANS</i>), and UDP-glucose flavonoid 3-O-glucosyltransferase (<i>UFGT3</i>), as well as the transcription factor <i>MYB1</i>, were found to be vital regulatory genes during the accumulation of anthocyanins in sweet potato leaves. The composition of anthocyanins (nine cyanidin-based anthocyanins and nine peonidin-based anthocyanins) in all sweet potato leaves were the same, but the quantity of anthocyanins in leaves of sweet potato varied by cultivar and differed from anthocyanin levels in the roots of sweet potatoes. The anthocyanidin biosynthesis structural genes and transcription factor together regulated and controlled the anthocyandin biosynthesis in sweet potato leaves.