Seasonal Below-Ground Metabolism in Switchgrass

Understanding winter survival in a perennial bioenergy grass.

The Science

Gene expression and metabolite data collected from rhizomes of field-grown switchgrass plants reveal that metabolism during dormancy involves discrete but interrelated events, providing further evidence that the internal and external environment is actively monitored by the plant even while over-wintering.

The Impact

Understanding the genetic mechanisms underlying rhizome metabolism in switchgrass during dormancy may provide tools that breeders can use to improve winter survival of this important bioenergy crop.


Switchgrass (Panicum virgatum) is a warm-season grass that is grown as a source of biomass for biofuels as well as for forage and conservation purposes.  As a perennial, the aerial tissues senesce at the end of each growing season while below-ground rhizomes become dormant.  The following spring, new tillers use stored carbon (C) and nitrogen (N) reserves to regenerate from these underground tissues, indicating that plant survival is dependent upon the ability of the rhizome to survive and remain healthy during cold winter temperatures.  However, little is known about the seasonal changes that occur during over-wintering of below-ground plant tissues.  To investigate the cellular processes involved with dormancy and to model the metabolic pathways operating during this phase, gene expression data was collected from rhizomes harvested from field-grown switchgrass plants over two growing seasons and analyzed together with metabolite data.  They found that metabolism in switchgrass rhizomes during the dormant period involves discrete but interrelated events, including cold-related signaling, that may be associated with the translocation of C, N, and other nutrients and regulate resource partitioning between above- and below-ground plant tissues throughout the year.  These results support that hypothesis that dormant switchgrass rhizomes are metabolically active, and pave the way for future studies to extend the range of switchgrass production into more northern climates.

Principal Investigator

Gautam Sarath
U.S. Department of Agriculture ARS
[email protected]

BER Program Manager

Kari Perez

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


DOE-USDA Plant Feedstocks Genomics for Bioenergy (DE-AI02-09ER64829); USDA NIFA (2011-67009-30096); USDA ARS CRIS (3042-21000-030-00D; 3042-21220-032-00D)


Palmer, N. A., A.J. Saathoff, E. D. Scully, C. M. Tobias, P. Twigg, S. Madhavan, M. Schmer, R. Cahoon, S. E. Sattler, S. J. Edmé, R. B. Mitchell, and G. Sarath. 2017. “Seasonal Below-Ground Metabolism in Switchgrass,” The Plant Journal 92(6) 1059–75. DOI:10.1111/tpj.13742.