Brassica napus TT16 homologs with different genomic origins and expression levels encode proteins that regulate a broad range of endothelium-associated genes at the transcriptional level

Authors

  • Guanqun Chen,

    1. Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
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    • These two authors contributed equally to this work and are regarded as co-first authors.
  • Wei Deng,

    1. Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
    Current affiliation:
    1. School of Life Science, Chongqing University, Chongqing, China
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    • These two authors contributed equally to this work and are regarded as co-first authors.
  • Fred Peng,

    1. Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
    Current affiliation:
    1. Livestock Gentec Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada
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  • Martin Truksa,

    1. Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
    Current affiliation:
    1. Emerging Technology Industries Branch, Enterprise and Advanced Education, Edmonton, AB, Canada
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  • Stacy Singer,

    1. Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
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  • Crystal L. Snyder,

    1. Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
    Current affiliation:
    1. Undergraduate Research Initiative, University of Alberta, Edmonton, AB, Canada
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  • Elzbieta Mietkiewska,

    1. Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
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  • Randall J. Weselake

    Corresponding author
    • Alberta Innovates Phytola Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
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For correspondence (e-mail randall.weselake@ualberta.ca).

Summary

The transcription factor TRANSPARENT TESTA 16 (TT16) plays an important role in endothelial cell specification and proanthocyanidin (PA) accumulation. However, its precise regulatory function with regard to the expression of endothelial-associated genes in developing seeds, and especially in the PA-producing inner integument, remains largely unknown. Therefore, we endeavored to characterize four TT16 homologs from the allotetraploid oil crop species Brassica napus, and systematically explore their regulatory function in endothelial development. Our results indicated that all four BnTT16 genes were predominantly expressed in the early stages of seed development, but at distinct levels, and encoded functional proteins. Bntt16 RNA interference lines exhibited abnormal endothelial development and decreased PA content, while PA polymerization was not affected. In addition to the previously reported function of TT16 in the transcriptional regulation of anthocyanidin reductase (ANR) and dihydroflavonol reductase (TT3), we also determined that BnTT16 proteins played a significant role in the transcriptional regulation of five other genes involved in the PA biosynthetic pathway (< 0.01). Moreover, we identified two genes involved in inner integument development that were strongly regulated by the BnTT16 proteins (TT2 and δ-vacuolar processing enzyme). These results will better our understanding of the precise role of TT16 in endothelial development in Brassicaceae species, and could potentially be used for the future improvement of oilseed crops.

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