Functional properties of an alternative, tissue-specific promoter for rice NADPH-dependent dihydroflavonol reductase

PLoS One. 2017 Aug 25;12(8):e0183722. doi: 10.1371/journal.pone.0183722. eCollection 2017.

Abstract

NADPH-dependent dihydroflavonol reductase (DFR) plays an important role in both anthocyanin biosynthesis and proanthocyanidin synthesis in plants. A specific and quantitative RT-PCR assay for transcription from the DFR promoter detected high expression with limited variability in rice tissues. A 440 bp minimal promoter region was identified by transfection of β-glucuronidase (GUS) reporter constructs into Jeokjinju variety. Alignment of the region with orthologous promoters revealed three conserved segments containing both bHLH (-386 to -381) and Myb (-368 to -362) binding sites. Transfection of β-glucuronidase constructs with targeted point mutations in the minimal promoter defined two sites important for promoter function to the transcription factor binding consensus sequences. The expression study showed that the bHLH binding domain (-386 to -381) is essential for DFR expression, and that a Myb binding domain (-368 to -362) is also required for full expression of the DFR gene, while the two bHLH binding domains (-104 to -99 and -27 to -22) nearest to the transcriptional start site are not necessary for DFR expression.

MeSH terms

  • Alcohol Oxidoreductases / genetics*
  • Glucuronidase / genetics
  • Mutagenesis, Site-Directed
  • NADP / metabolism*
  • Oryza / enzymology
  • Oryza / genetics*
  • Promoter Regions, Genetic*

Substances

  • NADP
  • Alcohol Oxidoreductases
  • dihydroflavanol 4-reductase
  • Glucuronidase

Grants and funding

We thank for the financial supports from the OECD Co-operative Research Programme, Fellowship 2010: Biological Resource Management for the Sustainable Agricultural System and from the National Research Foundation program (2014R1A 2A1A11052547) funded by the Ministry of Science, ICT and Future Planning, Republic of Korea.