Browsing by Subject "switchgrass"

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Adaptations Between Ecotypes And Along Environmental Gradients In Panicum Virgatum*
(2014-05) Lowry, David B.; Behrman, Kathrine D.; Grabowski, Paul; Morris, Geoffrey P.; Kiniry, James R.; Juenger, Thomas E.; Lowry, David B.; Juenger, Thomas E.
Determining the patterns and mechanisms of natural selection in the wild is of fundamental importance to understanding the differentiation of populations and the evolution of new species. However, it is often unknown the extent to which adaptive genetic variation is distributed among ecotypes between distinct habitats versus along large-scale geographic environmental gradients, such as those that track latitude. Classic studies of selection in the wild in switchgrass, Panicum virgatum, tested for adaptation at both of these levels of natural variation. Here we review what these field experiments and modern agronomic field trials have taught us about natural variation and selection at both the ecotype and environmental gradient levels in P. virgatum. With recent genome sequencing efforts in P. virgatum, it is poised to become an excellent system for understanding the adaptation of grassland species across the eastern half of North America. The identification of genetic loci involved in different types of adaptations will help to understand the evolutionary mechanisms of diversification within P. virgatum and provide useful information for the breeding of high-yielding cultivars for different ecoregions.
Future of Fuel
(The Texas Scientist, 2021) The Texas Scientist
Integrating Transcriptional, Metabolomic, and Physiological Responses to Drought Stress and Recovery in Switchgrass (Panicum Virgatum L.)
(2014-06) Meyer, Eli; Aspinwall, Michael J.; Lowry, David B.; Palacio-Mejia, Juan Diego; Logan, Tierney L.; Fay, Phillip A.; Juenger, Thomas E.; Meyer, Eli; Aspinwall, Michael J.; Lowry, David B.; Palacio-Mejia, Juan Diego; Logan, Tierney L.; Juenger, Thomas E.
In light of the changes in precipitation and soil water availability expected with climate change, understanding the mechanisms underlying plant responses to water deficit is essential. Toward that end we have conducted an integrative analysis of responses to drought stress in the perennial C-4 grass and biofuel crop, Panicum virgatum (switchgrass). Responses to soil drying and re-watering were measured at transcriptional, physiological, and metabolomic levels. To assess the interaction of soil moisture with diel light: dark cycles, we profiled gene expression in drought and control treatments under pre-dawn and mid-day conditions. Results: Soil drying resulted in reduced leaf water potential, gas exchange, and chlorophyll fluorescence along with differential expression of a large fraction of the transcriptome (37%). Many transcripts responded differently depending on time of day (e.g. up-regulation pre-dawn and down-regulation mid-day). Genes associated with C-4 photosynthesis were down-regulated during drought, while C-4 metabolic intermediates accumulated. Rapid changes in gene expression were observed during recovery from drought, along with increased water use efficiency and chlorophyll fluorescence. Conclusions: Our findings demonstrate that drought responsive gene expression depends strongly on time of day and that gene expression is extensively modified during the first few hours of drought recovery. Analysis of covariation in gene expression, metabolite abundance, and physiology among plants revealed non-linear relationships that suggest critical thresholds in drought stress responses. Future studies may benefit from evaluating these thresholds among diverse accessions of switchgrass and other C-4 grasses.