Light and temperature effects on miR156 transgenic switchgrass flowering: A simulated latitudinal study
- Univ. of Tennessee, Knoxville, TN (United States)
- Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC); Noble Research Institute, LLC, Ardmore, OK (United States)
The control of flowering in perennial grasses is an important trait, especially among biofuel feedstocks. Lignocellulosic biomass may be increased commensurate with decreased or delayed flowering as the plant allocates energy for stems and leaves harvested for bioenergy at the end of the growing season. For transgenic feedstocks, such as switchgrass (Panicum virgatum L.) grown in its geographic center of distribution, it is foreseeable that regulators may require greatly decreased gene flow frequencies to enable commercialization. Transgenic switchgrass with various overexpression levels of a rice microRNA gene, miR156, when grown in field conditions, holds promise for decreased flowering, yielding high biomass, and altered cell wall traits, which renders it as a potential crossing partner for further breeding with switchgrass lines for decreased recalcitrance. In the current research, we simulated a latitudinal cline in controlled growth chamber experiments for various individual sites from the tropics to cool-temperate conditions which included weekly average high and low temperatures and day lengths over the switchgrass growing season for each simulated site: Guayaquil, Ecuador; Laredo, Texas, USA; and Brattleboro, Vermont, USA. Flowering and reproduction among transgenic lines with low (T-14 and T-35)--tomoderate (T-27 and T-37) overexpression of miR156 were assessed. Lower simulated latitudes (higher temperatures with low-variant day length) and long growing seasons promoted flowering of the miR156 transgenic switchgrass lines. Tropical conditions rescued the flowering phenotype in all transgenic lines except T-27. Higher numbers of plants in lines T-35 and T-37 and the controls produced panicles, which also occurred earlier in the study as temperatures increased and day length decreased. Line T-14 was the exception as more clonal replicates flowered in the cool-temperate (Vermont) conditions. Increased biomass was found in transgenic lines T-35 and T-37 in tropical conditions. No difference in biomass was found in subtropical (Texas) chambers, and two lines (T-14 and T-35) produced less biomass than the control in cool-emperate conditions. Our findings suggest that switchgrass plants engineered to overexpress miR156 for delayed flowering to promote bioconfinement and biomass production may be used for plant breeding at tropical sites.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC)
- Sponsoring Organization:
- USDOE; USDA, National Institute of Food and Agriculture (NIFA)
- Grant/Contract Number:
- 2013-33522-20997
- OSTI ID:
- 1623581
- Journal Information:
- Plant Direct, Vol. 1, Issue 5; ISSN 2475-4455
- Publisher:
- Wiley and American Society of Plant Biologists and Society for Experimental BiologyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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journal | October 2018 |
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