Location: Wheat, Sorghum and Forage ResearchTitle: Seasonal below-ground metabolism in switchgrass
|Palmer, Nathan - Nate|
|SAATHOFF, AARON - Licor Biosciences|
|TWIGG, PAUL - University Of Nebraska|
|MADHAVAN, SOUNDARARAJAN - University Of Nebraska|
|CAHOON, REBECCA - University Of Nebraska|
|Mitchell, Robert - Rob|
Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2017
Publication Date: 12/6/2017
Publication URL: http://handle.nal.usda.gov/10113/5872564
Citation: Palmer, N.A., Saathoff, A.J., Scully, E.D., Tobias, C.M., Twigg, P., Madhavan, S., Schmer, M.R., Cahoon, R., Sattler, S.E., Edme, S.J., Mitchell, R., Sarath, G. 2017. Seasonal below-ground metabolism in switchgrass. Plant Journal. 92(6):1059-1075. https://doi.org/:10.1111/tpj.13742.
Interpretive Summary: Switchgrass is a key species being evaluated for use as a multipurpose crop for marginal farm lands. Seasonal regrowth of shoots (collectible biomass) occurs from the below-ground rhizomes. Rhizome metabolism during winter dormancy is likely to impact survival, thereby impacting plant stands and sustainability of biomass production. A detailed understanding of seasonal rhizome metabolism will be useful to improve winter hardiness of high yielding germplasm, and to develop cultivars with greater adaptation to the Central Great Plains. In this study, rhizome tissues obtained from field-grown plants of the cultivar Summer, which is well adapted to the Central Great Plains, were assessed over two growing seasons using a combination of high-throughput DNA sequencing and analysis of metabolites. These data were used to identify key genes and metabolic pathways that could be of importance during switchgrass rhizome dormancy. Lastly, models of rhizome metabolism especially during dormancy were developed that could provide new knowledge of pathways that significantly impact switchgrass rhizome survival over the winter months in the Central Great Plains. These datasets will provide information that can be applied in breeding programs to improve this important perennial crop.
Technical Abstract: Switchgrass (Panicum virgatum) a perennial, polyploid, C4 warm-season grass is one of the foremost herbaceous species being advanced as a source of biomass for biofuel end uses. At the end of every growing season, the aerial tissues senesce, and the below-ground rhizomes become dormant. Future growth is dependent on the successful over-wintering of the rhizomes. Although the importance of rhizome health to overall year-upon-year plant productivity has been long recognized, there is a paucity of information on the seasonal changes occurring during dormancy at both the transcriptome and metabolite levels. Here, global changes in transcriptomes and metabolites were investigated over two growing seasons in rhizomes harvested from field-grown plants. The objectives were to (a) synthesize information on cellular processes that lead to dormancy and to (b) provide models that could account for major metabolic pathways present in dormant switchgrass rhizomes. Overall, metabolism during dormancy appears to involve two discrete but interrelated events. One was a response primarily driven by ABA that resulted in dehydration, increases in cellular osmolytes, and upregulation of autophagic processes, likely through the target of rapamycin complex and sucrose non-fermentative related kinase based signaling cascades. The other was a recalibration of energy transduction through apparent reductions in mitochondrial oxidative phosphorylation, increases in substrate level generation of ATP and reducing equivalents, recycling of N and possibly CO2 through refixation. Altogether, these data provide a detailed overview of rhizome metabolism, especially during dormancy, which can be exploited in the future to improve winter survival in switchgrass.