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

Abstract

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, p-coumaryl, feruloyl, and p-hydroxy benzoyl. We identified three anthocyanin compounds in sweet potato leaves for the first time: cyanidin 3-p-coumarylsophoroside-5-glucoside, peonidin 3-p-coumarylsophoroside-5-glucoside, and cyanidin 3-caffeoyl-p-coumarylsophoroside-5-glucoside. The anthocyanidin biosynthesis downstream structural genes DFR4, F3H1, anthocyanin synthase (ANS), and UDP-glucose flavonoid 3-O-glucosyltransferase (UFGT3), as well as the transcription factor MYB1, 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.

Identification of the Genes Involved in Anthocyanin Biosynthesis and Accumulation in Taxus chinensis

“…A number of studies about transcriptomics and metabonomics in anthocyanin biosynthesis revealed that the expression levels of structural genes play an important role in anthocyanin accumulation, especially DFR, ANS, and F3H [55][56][57][58]. DFR and ANS are considered as very important enzymes in anthocyanin biosynthesis, as they could direct the flavonoid flux into the anthocyanin branch [55][56][57][58]. Previous studies showed that the expression levels of DFR, ANS, and F3H and some transcription factors were positively correlated with anthocyanin accumulation.…”

Determination of TLC fingerprint biomarker of Ipomoea batatas (L.) Lam leaves extracted with ethanol and its potential as antihyperglycemic agent

“…The main anthocyanin aglycones in I. batatas leaves are cyanidin and peonidin (Islam et al 2002, Li et al 2019. Likewise, in EIBL, cyanidin and peonidin aglycone were also found, dominating the glycosides and their acylated derivatives.…”

The Expression of IbMYB1 Is Essential to Maintain the Purple Color of Leaf and Storage Root in Sweet Potato [Ipomoea batatas (L.) Lam]

“…The quantitative reverse transcription PCR (RT-qPCR) was performed to determine the transcript levels of genes using AceQ SYBR qPCR Master Mix (Vazyme Biotech Co., Ltd.) and a real-time PCR system (LightCycler 960, Roche Diagnostics, Basel, Switzerland). The genes for the RT-qPCR amplification were confirmed to be closely related to the regulation of anthocyanin synthesis (Mano et al, 2007;Li et al, 2019;Deng et al, 2020). The primers for these genes were synthesized according to a previous study (Deng et al, 2020) and are listed in Supplementary Table 1.…”

“…R2R3-MYBs such as IbMYB1 can independently initiate the transcription of anthocyanin biosynthesis genes ( Stracke et al, 2007 ; Dubos et al, 2008 ; Dong, 2014 ; Dong et al, 2014 ) or can interact with other TFs to form the MBW complex to activate anthocyanin biosynthesis in sweet potato and other plants ( Dubos et al, 2008 ; Davies et al, 2012 ; Zhu et al, 2015 ; Deng et al, 2020 ; Yan et al, 2021 ). It has been confirmed that IbMYB1-2 plays a vital regulatory role in anthocyanin accumulation in storage roots ( Tanaka et al, 2011 ), but it is not necessary in all varieties for the expression of IbMYB1 ( Kim et al, 2010 ; Li et al, 2019 ; Zhang et al, 2020 ). A major locus of chromosome 5, where IbMYB1 genes are located, has been shown to have a large effect on the color variation of shoots ( Chen et al, 2021 ).…”