The upregulation of NtAN2 expression at low temperature is required for anthocyanin accumulation in juvenile leaves of Lc-transgenic tobacco (Nicotiana tabacum L.)

J Genet Genomics. 2012 Mar 20;39(3):149-56. doi: 10.1016/j.jgg.2012.01.007. Epub 2012 Feb 14.

Abstract

Anthocyanins often accumulate in plants subjected to environmental stress, including low temperature. However, the molecular regulatory mechanism of anthocyanin biosynthesis at low temperature is largely unknown. Here, tobacco was transformed with a maize anthocyanin regulatory gene Lc driven by AtSPX3 promoter to investigate the effect of Lc upon the anthocyanin-biosynthesis pathway. We found that the anthocyanin-biosynthesis pathway could not be activated in wild type, while Lc-transgenic tobacco lines exhibited purple pigmentation in juvenile leaves at low temperature. Accordingly, the total anthocyanin contents increased specifically in juvenile leaves in Lc-transgenic lines. Transcriptional analysis showed that NtCHS and NtCHI were induced by low temperature in leaves of wild type and transgenic lines. NtDFR was uniquely expressed in Lc-transgenic lines, but its transcript was not detected in wild type, implying that NtDFR expression in tobacco leaves was dependent on Lc. Furthermore, the expression of NtAN2 (regulatory gene) and NtANS (anthocyanidin synthase gene) was coordinately upregulated in Lc-transgenic lines under low temperature, suggesting that both Lc and NtAN2 might activate the expression of NtANS. Based on our findings and previous reports, we postulated that Lc interacted with NtAN2 induced by low-temperature stress and consequently stimulated anthocyanin biosynthesis in juvenile leaves of Lc-transgenic tobacco lines.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthocyanins / biosynthesis
  • Anthocyanins / metabolism*
  • Cold Temperature
  • Gene Expression Regulation, Plant
  • Nicotiana / genetics*
  • Nicotiana / metabolism
  • Oxygenases / genetics
  • Oxygenases / metabolism
  • Plant Leaves / genetics*
  • Plant Leaves / metabolism
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plants, Genetically Modified
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Up-Regulation

Substances

  • Anthocyanins
  • Lc protein, Zea mays
  • Plant Proteins
  • Transcription Factors
  • Oxygenases
  • anthocyanidin synthase