Transgenic miR156 Switchgrass in the Field: Growth, Recalcitrance and Rust Susceptibility

Holly L. Baxter, Mitra Mazarei, Alexandru Dumitrache, Jace M. Natzke, Miguel Rodriguez, Jiqing Gou, Chunxiang Fu, Robert W. Sykes, Geoffrey B. Turner, Mark F. Davis, Steven D. Brown, Brian H. Davison, Zeng Yu Wang, C. Neal Stewart

Research output: Contribution to journalArticlepeer-review

22 Scopus Citations


Sustainable utilization of lignocellulosic perennial grass feedstocks will be enabled by high biomass production and optimized cell wall chemistry for efficient conversion into biofuels. MicroRNAs are regulatory elements that modulate the expression of genes involved in various biological functions in plants, including growth and development. In greenhouse studies, overexpressing a microRNA (miR156) gene in switchgrass had dramatic effects on plant architecture and flowering, which appeared to be driven by transgene expression levels. High expressing lines were extremely dwarfed, whereas low and moderate-expressing lines had higher biomass yields, improved sugar release and delayed flowering. Four lines with moderate or low miR156 overexpression from the prior greenhouse study were selected for a field experiment to assess the relationship between miR156 expression and biomass production over three years. We also analysed important bioenergy feedstock traits such as flowering, disease resistance, cell wall chemistry and biofuel production. Phenotypes of the transgenic lines were inconsistent between the greenhouse and the field as well as among different field growing seasons. One low expressing transgenic line consistently produced more biomass (25%–56%) than the control across all three seasons, which translated to the production of 30% more biofuel per plant during the final season. The other three transgenic lines produced less biomass than the control by the final season, and the two lines with moderate expression levels also exhibited altered disease susceptibilities. Results of this study emphasize the importance of performing multiyear field studies for plants with altered regulatory transgenes that target plant growth and development.

Original languageAmerican English
Pages (from-to)39-49
Number of pages11
JournalPlant Biotechnology Journal
Issue number1
StatePublished - Jan 2018

Bibliographical note

Publisher Copyright:
© 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

NREL Publication Number

  • NREL/JA-5100-68393


  • bioconfinement
  • biomass
  • flowering
  • microRNA156
  • switchgrass
  • transgene regulation


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