A R2R3-MYB transcription factor from Epimedium sagittatum regulates the flavonoid biosynthetic pathway

PLoS One. 2013 Aug 1;8(8):e70778. doi: 10.1371/journal.pone.0070778. Print 2013.

Abstract

Herba epimedii (Epimedium), a traditional Chinese medicine, has been widely used as a kidney tonic and antirheumatic medicine for thousands of years. The bioactive components in herba epimedii are mainly prenylated flavonol glycosides, end-products of the flavonoid pathway. Epimedium species are also used as garden plants due to the colorful flowers and leaves. Many R2R3-MYB transcription factors (TFs) have been identified to regulate the flavonoid and anthocyanin biosynthetic pathways. However, little is known about the R2R3-MYB TFs involved in regulation of the flavonoid pathway in Epimedium. Here, we reported the isolation and functional characterization of the first R2R3-MYB TF (EsMYBA1) from Epimedium sagittatum (Sieb. Et Zucc.) Maxim. Conserved domains and phylogenetic analysis showed that EsMYBA1 belonged to the subgroup 6 clade (anthocyanin-related MYB clade) of R2R3-MYB family, which includes Arabidopsis AtPAP1, apple MdMYB10 and legume MtLAP1. EsMYBA1 was preferentially expressed in leaves, especially in red leaves that contain higher content of anthocyanin. Alternative splicing of EsMYBA1 resulted in three transcripts and two of them encoded a MYB-related protein. Yeast two-hybrid and transient luciferase expression assay showed that EsMYBA1 can interact with several bHLH regulators of the flavonoid pathway and activate the promoters of dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (ANS). In both transgenic tobacco and Arabidopsis, overexpression of EsMYBA1 induced strong anthocyanin accumulation in reproductive and/or vegetative tissues via up-regulation of the main flavonoid-related genes. Furthermore, transient expression of EsMYBA1 in E. sagittatum leaves by Agrobacterium infiltration also induced anthocyanin accumulation in the wounded area. This first functional characterization of R2R3-MYB TFs in Epimedium species will promote further studies of the flavonoid biosynthesis and regulation in medicinal plants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Alcohol Oxidoreductases / genetics
  • Alternative Splicing
  • Amino Acid Sequence
  • Anthocyanins / biosynthesis
  • Arabidopsis / genetics
  • Cell Nucleus / metabolism
  • Epimedium / cytology
  • Epimedium / genetics
  • Epimedium / metabolism*
  • Flavonoids / biosynthesis*
  • Gene Expression Regulation, Plant
  • Genomics
  • Molecular Sequence Data
  • Nicotiana / genetics
  • Organ Specificity
  • Oxygenases / genetics
  • Plant Leaves / metabolism
  • Plant Proteins / chemistry
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Plants, Genetically Modified
  • Promoter Regions, Genetic / genetics
  • Sequence Analysis
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Anthocyanins
  • Flavonoids
  • Plant Proteins
  • Transcription Factors
  • Alcohol Oxidoreductases
  • dihydroflavanol 4-reductase
  • Oxygenases
  • anthocyanidin synthase

Grants and funding

This study was supported by grants from the National Natural Science Foundation of China (No. 31270340, 31200225), and CAS/SAFEA International Partnership Program for Creative Research Teams Project and Knowledge Innovation Project of The Chinese Academy of Sciences (KSCX2-EW-J-20). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.