Overexpression of ThMYC4E Enhances Anthocyanin Biosynthesis in Common Wheat.

Shuo Zhao,Xingyuan Xi,Yuan Zong,Yun Li,Baolong Liu,Dong Cao,Shiming Li

doi:10.3390/ijms21010137

Abstract

The basic helix-loop helix (bHLH) transcription factor has been inferred to play an important role in blue and purple grain traits in common wheat, but to date, its overexpression has not been reported. In this study, the bHLH transcription factor ThMYC4E, the candidate gene controlling the blue grain trait from Th. Ponticum, was transferred to the common wheat JW1. The positive transgenic lines displayed higher levels of purple anthocyanin pigments in their grains, leaves and glumes. Stripping the glumes (light treatment) caused white grains to become purple in transgenic lines. RNA-Seq and qRT-PCR analysis demonstrated that the transcript levels of structural genes associated with anthocyanin biosynthesis were higher in transgenic wheat than the wild-type (WT), which indicated that ThMYC4E activated anthocyanin biosynthesis in the transgenic lines. Correspondingly, the anthocyanin contents in grains, roots, stems, leaves and glumes of transgenic lines were higher than those in the WT. Metabolome analysis demonstrated that the anthocyanins were composed of cyanidin and delphinidin in the grains of the transgenic lines. Moreover, the transgenic lines showed higher antioxidant activity, in terms of scavenging DPPH radicals, in the ethanol extracts of their grains. The overexpression of ThMYC4E sheds light on the traits related to anthocyanin biosynthesis in common wheat and provide a new way to improve anthocyanin content.

Highlights

Anthocyanins are glycosylated polyphenolic compounds that vary in color from orange and red to purple and blue in flowers, seeds, fruits and vegetative tissues [1,2]
Transgenic Lines Overexpressing ThMYC4E Were Characterized by Colored Tissues
Because the basic helix-loop helix (bHLH) transcription factor was inferred to play an important role in the formation of blue and purple grain traits, the grains were transected and the pericarps and aleurone appeared dark (Figure 1A)

Summary

Introduction

Anthocyanins are glycosylated polyphenolic compounds that vary in color from orange and red to purple and blue in flowers, seeds, fruits and vegetative tissues [1,2]. As anthocyanins are water-soluble pigments that are mostly located in cell vacuoles, their hues are influenced by the intravacuolar environment [3,4,5]. Over 600 anthocyanins have been identified in Nature. The most common are the derivatives of six widespread anthocyanidins, namely pelargonidin, cyanidin, delphinidin, peonidin, petunidin and malvidin. Anthocyaninscan protect plants against various biotic and abiotic stresses [6], partially due to their powerful antioxidant properties. Anthocyanin-rich food products have become increasingly popular, due to their attractive colors and suggested benefits to human health [4,7,8]

Methods

Results

Discussion

Conclusion