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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED FORAGE AND BIOENERGY PLANTS AND TECHNOLOGIES FOR THE CENTRAL USA Title: Contrasting metabolism in perenniating structures of upland and lowland switchgrass plants late in the growing season

Authors
item Palmer, Nathan
item Saathoff, Aaron
item Tobias, Christian
item Twigg, Paul -
item Xia, Yuannan -
item Vogel, Kenneth
item Madhavan, Soundararajan -
item Sattler, Scott
item Sarath, Gautam

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 19, 2014
Publication Date: August 18, 2014
Repository URL: http://handle.nal.usda.gov/10113/59511
Citation: Palmer, N.A., Saathoff, A.J., Tobias, C.M., Twigg, P., Xia, Y., Vogel, K.P., Madhavan, S., Sattler, S.E., Sarath, G. 2014. Contrasting metabolism in perenniating structures of upland and lowland switchgrass plants late in the growing season. PLoS One. 9/1-11.

Interpretive Summary: Switchgrass (Panicum virgatum L.) is a perennial grass native to the USA that is being developed as a bioenergy crop for temperate regions of the world. Its ability to survive winters and produce new growth the following spring is an essential factor of its value as an energy crop. The molecular genetics and physiological processes controlling dormancy and regrowth in switchgrass were studied using large scale sequencing of RNA extracted from plant crown and rhizome tissue of switchgrass cultivars with contrasting winter adaptation. The results demonstrate that in autumn, many molecular processes associated with dormancy were evident in plants of the well adapted, but lower yielding cultivar Summer as compared to the higher yielding but less well adapted cultivar Kanlow. These molecular genetic datasets obtained in this research will provide information that can be used in breeding programs to improve this important bioenergy crop.

Technical Abstract: Switchgrass (Panicum virgatum L.) is a perennial grass native to the USA that is being developed as a bioenergy crop for temperate regions of the world. Its ability to survive winters and produce new growth the following spring is an essential factor of its value as an energy crop. We have explored crown and rhizome metabolism of two contrasting tetraploid populations of switchgrass, cv Kanlow, a lowland ecotype with high yields but poor winter survival, and cv Summer, an upland ecotype with lower yields and excellent, higher winter survival to understand cellular metabolism as the plants transition to winter dormancy. Significant differences existed in transcript abundances for 9561 genes, including nutrient transporters, WRKY transcription factors and a large specific class of proteins (NB-ARC domain) involved in defense. Principal component analysis (PCA) differentiated between Summer and Kanlow transcriptomes. PCA of metabolites identified by GCMS supported the transcriptomic data, and again differentiated the Kanlow and Summer metabolomes. Gene-set enrichment analyses, showed that a number of pathways were differentially up-regulated in the two ecotypes. For both populations, protein levels and enzyme activities agreed well with transcript abundances for genes involved in the phenylpropanoid pathway which was up-regulated in Kanlow crowns and rhizomes. For Summer plants, key events appear to be changes in cellular redox status and metabolic redirection with acetyl-CoA as a hub in Summer plants, potentially as an integrated response to loss in photosynthate and environmental cues (short days and cooler nights).

Last Modified: 11/28/2014
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