Title: Transgenic miR156 switchgrass in the field: growth, recalcitrance and rust susceptibility

Abstract

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 analyzed 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 threemore » 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 multi-year field studies for plants with altered regulatory transgenes that target plant growth and development.« less

Authors:

Baxter, Holly L. ^[1]; Mazarei, Mitra ^[1]; Dumitrache, Alexandru ^[2]; Natzke, Jace M. ^[2]; Rodriguez, Miguel ^[2]; Gou, Jiqing ^[3]; Fu, Chunxiang ^[3]; Sykes, Robert W. ^[4]; Turner, Geoffrey B. ^[4]; Davis, Mark F. ^[4]; Brown, Steven D. ^[2]; Davison, Brian H.  ^[2];

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Wang, Zeng-Yu ^[3]; Stewart, C. Neal ^[1]

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+ Show Author Affiliations

1. Department of Plant Sciences, University of Tennessee, Knoxville TN USA; BioEnergy Science Center (BESC), Oak Ridge National Laboratory, Oak Ridge TN USA
2. BioEnergy Science Center (BESC), Oak Ridge National Laboratory, Oak Ridge TN USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge TN USA
3. BioEnergy Science Center (BESC), Oak Ridge National Laboratory, Oak Ridge TN USA; Samuel Roberts Noble Foundation, Ardmore OK USA
4. BioEnergy Science Center (BESC), Oak Ridge National Laboratory, Oak Ridge TN USA; National Renewable Energy Laboratory, Golden CO USA

Publication Date:

Mon Apr 24 00:00:00 EDT 2017

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1364675

Alternate Identifier(s):

OSTI ID: 1364676; OSTI ID: 1376550; OSTI ID: 1395091

Report Number(s):

NREL/JA-5100-68393
Journal ID: ISSN 1467-7644

Grant/Contract Number:  

AC05-00OR22725; AC36-08GO28308

Resource Type:

Published Article

Journal Name:

Plant Biotechnology Journal

Additional Journal Information:

Journal Name: Plant Biotechnology Journal Journal Volume: 16 Journal Issue: 1; Journal ID: ISSN 1467-7644

Publisher:

Society for Experimental Biology; Association of Applied Biology

Country of Publication:

United Kingdom

Language:

English

Subject:

60 APPLIED LIFE SCIENCES; microRNA156; biomass; transgene regulation; switchgrass; flowering; bioconfinement; 09 BIOMASS FUELS; gene expression