Expression of the sweetpotato R2R3‐type IbMYB1a gene induces anthocyanin accumulation in Arabidopsis

Abstract

R2R3-type MYB transcription factors (TFs) play important roles in transcriptional regulation of anthocyanins. The R2R3-type IbMYB1 is known to be a key regulator of anthocyanin biosynthesis in the storage roots of sweetpotato. We previously showed that transient expression of IbMYB1a led to anthocyanin pigmentation in tobacco leaves. In this article, we generated transgenic Arabidopsis plants expressing the IbMYB1a gene under the control of CaMV 35S promoter, and the sweetpotato SPO and SWPA2 promoters. Overexpression of IbMYBa in transgenic Arabidopsis produced strong anthocyanin pigmentation in seedlings and generated a deep purple color in leaves, stems and seeds. Reverse transcription-polymerase chain reaction analysis showed that IbMYB1a expression induced upregulation of several structural genes in the anthocyanin biosynthetic pathway, including 4CL, CHI, F3'H, DFR, AGT, AAT and GST. Furthermore, overexpression of IbMYB1a led to enhanced expression of the AtTT8 (bHLH) and PAP1/AtMYB75 genes. high-performance liquid chromatography analysis revealed that IbMYB1a expression led to the production of cyanidin as a major core molecule of anthocyanidins in Arabidopsis, as occurs in the purple leaves of sweetpotato (cv. Sinzami). This result shows that the IbMYB1a TF is sufficient to induce anthocyanin accumulation in seedlings, leaves, stems and seeds of Arabidopsis plants.

Anthocyanins accumulate in tartary buckwheat (Fagopyrum tataricum) sprout in response to cold stress

“…Anthocyanins were extracted and measured using the method described by Chu et al (2012). All samples were measured in triplicate from two independent biological replicates.…”

Enhanced production of resveratrol derivatives in tobacco plants by improving the metabolic flux of intermediates in the phenylpropanoid pathway

“…Total anthocyanins were extracted from 0.1 g of finely ground flower tissue and measured spectrophotometrically at the wavelengths 530 and 657 nm as described by Chu et al (2013).…”

“…As a general strategy, transcriptionally activating the upstream pathway might increase the metabolic flux of intermediates and provide more substrates. We previously reported (Chu et al 2013;) that overexpression of IbMYB1a in Arabidopsis and tobacco plants led to anthocyanin pigmentation through the transcriptional activation of structural genes in the anthocyanin biosynthetic pathway. Moreover, in the present study, we noted that the biosynthetic genes encoding PAL, C4H, and 4CL enzymes in the phenylpropanoid pathway were upregulated by IbMYB1a expression (Fig.…”

Heterologous expression of IbMYB1a by different promoters exhibits different patterns of anthocyanin accumulation in tobacco

“…Recently, Park et al (2015) reported that overexpression of IbMYB1a in a single orange-fleshed sweetpotato cultivar generated dual-pigmented transgenic plants with high levels of both anthocyanins and carotenoids in their storage roots. In addition, the expression of IbMYB1a alone was sufficient for heterologous activation of anthocyanin biosynthesis in transiently agro-infiltrated tobacco leaves and stably transformed Arabidopsis plants (Chu et al, 2013;Kim et al, 2010;Mano et al, 2007). Identifying the interacting partners of IbMYB1a TF is necessary for elucidating the gene regulatory networks controlling anthocyanin biosynthesis in purple-fleshed sweetpotato.…”