Contrasting Metabolism in Perenniating Structures of Upland and Lowland Switchgrass Plants Late in the Growing Season

Authors

Nathan Palmer, USDA ARS, Lincoln, NEFollow
Aaron J. Saathoff, LI-COR Biosciences, Lincoln, Nebraska,Follow
Christian M. Tobias, USDA ARS, Albany CAFollow
Paul Twigg, University of Nebraska at KearneyFollow
Yuannan Xia, University of Nebraska-LincolnFollow
Kenneth P. Vogel, USDA ARS, Lincoln, NEFollow
Soundararajan Madhavan, University of Nebraska-LincolnFollow
Scott E. Sattler, USDA-ARSFollow
Gautam Sarath, USDA-ARSFollow

Document Type

Article

Date of this Version

8-18-2014

Citation

PLoS ONE 9(8): e105138. doi:10.1371/journal.pone.0105138

Comments

US gov't work.

Abstract

Background: Switchgrass (Panicum virgatum L.) is being developed as a bioenergy crop for many temperate regions of the world. One way to increase biomass yields is to move southern adapted lowland cultivars to more northern latitudes. However, many southerly adapted switchgrass germplasm can suffer significant winter kill in northerly climes.

Materials and Methods: Here, we have applied next-generation sequencing in combination with biochemical analyses to query the metabolism of crowns and rhizomes obtained from two contrasting switchgrass cultivars. Crowns and rhizomes from field-grown lowland (cv Kanlow) and upland (cv Summer) switchgrass cultivars were collected from three randomly selected post-flowering plants. Summer plants were senescing, whereas Kanlow plants were not at this harvest date.

Results: Principal component analysis (PCA) differentiated between both the Summer and Kanlow transcriptomes and metabolomes. Significant differences in transcript abundances were detected for 8,050 genes, including transcription factors such as WRKYs and those associated with phenylpropanoid biosynthesis. Gene-set enrichment analyses showed that a number of pathways were differentially up-regulated in the two populations. For both populations, protein levels and enzyme activities agreed well with transcript abundances for genes involved in the phenylpropanoid pathway that were upregulated in Kanlow crowns and rhizomes. The combination of these datasets suggests that dormancy-related mechanisms had been triggered in the crowns and rhizomes of the Summer plants, whereas the crowns and rhizomes of Kanlow plants had yet to enter dormancy.

Conclusions: Delayed establishment of dormancy at more northerly latitudes could be one factor that reduces wintersurvival in the high-yielding Kanlow plants. Understanding the cellular signatures that accompany the transition to dormancy can be used in the future to select plants with improved winter hardiness.