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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

SPL 7 and SPL 8 represent a novel flowering regulation mechanism in switchgrass

Summary The aging pathway in flowering regulation is controlled mainly by micro RNA 156 (miR156). Studies in Arabidopsis thaliana reveal that nine miR156‐targeted SQUAMOSA PROMOTER BINDING ‐ LIKE ( SPL ) genes are involved in the control of flowering. However, the roles of SPL s in flowering remain elusive in grasses. Inflorescence development in switchgrass was characterized using scanning electron microscopy ( SEM ). Microarray, quantitative reverse transcription polymerase chain reaction (q RT ‐ PCR ), chromatin immunoprecipitation (Ch IP )‐ PCR and EMSA were used to identify regulators of phase transition and flowering. Gene function was characterized by downregulation and overexpression of the target genes. Overexpression of SPL 7 and SPL 8 promotes flowering, whereas downregulation of individual genes moderately delays flowering. Simultaneous downregulation of SPL 7 / SPL 8 results in extremely delayed or nonflowering plants. Furthermore, downregulation of both genes leads to a vegetative‐to‐reproductive reversion in the inflorescence, a phenomenon that has not been reported in any other grasses. Detailed analyses demonstrate that SPL 7 and SPL 8 induce phase transition and flowering in grasses by directly upregulating SEPALLATA3 ( SEP 3 ) and MADS 32 . Thus, the SPL 7 / 8 pathway represents a novel regulatory mechanism in grasses that is largely different from that in Arabidopsis . Additionally, genetic modification of SPL 7 and SPL8 results in much taller plants with significantly increased biomass yield and sugar release.

Gou, Jiqing↗
DOE OSTI2016

Transgenic switchgrass ( Panicum virgatum L.) targeted for reduced recalcitrance to bioconversion: A two-year comparative analysis of field-grown lines modified for target gene or genetic element expression

Five different types of transgenic ( GAUT4 , miRNA, MYB4, COMT and FPGS ) Panicum virgatum L. (switchgrass) were grown in a field in Knoxville, Tenn., USA over two consecutive years between 2011 and 2015 in separate experiments. Clonal replicates were established (year-one) and produced much greater biomass during the second year. After each growing season the above ground biomass was analyzed for cell wall sugars and for recalcitrance to enzymatic digestibility, and biofuel using a separate hydrolysis and fermentation (SHF) screen. Here, each transgenic event and control had more glucan, xylan and less ethanol (g/g basis) from the second year of growth relative to the first year plants. There was no correlation between plant carbohydrate content and biofuel production. In each of cell wall-targeted transgenics, GAUT4 , MYB4, COMT and FPGS , the second year of growth resulted in increased carbohydrate abundance (up to 12%) and reduced recalcitrance through higher ethanol yields (up to 21%) over the non-transgenic control plants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Characterization of switchgrass ( Panicum virgatum L.) PvKSL1 as a levopimaradiene/abietadiene‐type diterpene synthase

Abstract The diverse class of plant diterpenoid metabolites serves important functions in mediating growth, chemical defence, and ecological adaptation. In major monocot crops, such as maize (Zea mays), rice (Oryza sativa), and barley (Hordeum vulgare), diterpenoids function as core components of biotic and abiotic stress resilience. Switchgrass (Panicum virgatum) is a perennial grass valued as a stress‐resilient biofuel model crop. Previously we identified an unusually large diterpene synthase family that produces both common and species‐specific diterpenoids, several of which accumulate in response to abiotic stress. Here, we report discovery and functional characterization of a previously unrecognized monofunctional class I diterpene synthase (PvKSL1) viain vivoco‐expression assays with different copalyl pyrophosphate (CPP) isomers, structural and mutagenesis studies, as well as genomic and transcriptomic analyses. In particular, PvKSL1 convertsent‐CPP intoent‐abietadiene,ent‐palustradiene,ent‐levopimaradiene, andent‐neoabietadiene via a 13‐hydroxy‐8(14)‐ent‐abietene intermediate. Notably, although featuring a distinctent‐stereochemistry, this product profile is near‐identical to bifunctional (+)‐levopimaradiene/abietadiene synthases occurring in conifer trees. PvKSL1 has three of four active site residues previously shown to control (+)‐levopimaradiene/abietadiene synthase catalytic specificity. However, mutagenesis studies suggest a distinct catalytic mechanism in PvKSL1. Genome localization ofPvKSL1distant from other diterpene synthases, and its phylogenetic distinctiveness from known abietane‐forming diterpene synthases, support an independent evolution of PvKSL1 activity. Albeit at low levels,PvKSL1gene expression predominantly in roots suggests a role of diterpenoid formation in belowground tissue. Together, these findings expand the known chemical and functional space of diterpenoid metabolism in monocot crops.

Plant Sciences↗
DOE OSTI2022

Cold acclimation threshold induction temperatures of switchgrass ecotypes grown under a long and short photoperiod

Abstract Plants can cold acclimate to enhance their freezing tolerance by sensing declining temperature and photoperiod cues. However, the factors influencing genotypic variation in the induction of cold acclimation are poorly understood among perennial grasses. We hypothesized that the more northern upland switchgrass ( Panicum virgatum L.) ecotype develops a higher degree of freezing tolerance by initiating cold acclimation at higher temperatures as compared with the coastal and southern lowland ecotypes. First, we determined the optimal method for assessing freezing tolerance and the length of exposure to 8/4°C required to induce the maximum level of freezing tolerance in the most northern upland and most southern lowland genotypes. We characterized the maximum freezing tolerance of eight uplands, three coastal and five lowland genotypes grown for 21 days at 8/4°C and a 10 or 16 h photoperiod. Next, we identified the temperature required to induce cold acclimation by exposing the 16 genotypes for 7 days at 20–6°C constant temperatures under a 10 or 16 h photoperiod. Cold acclimation initiated at temperatures 5 and 7°C higher in upland than in coastal and lowland genotypes. Among upland genotypes the shorter photoperiod induced cold acclimation at a 1°C higher temperature. Genotypes originating from a more northern latitude initiate cold acclimation at higher temperatures and develop higher maximum freezing tolerances. An earlier response to declining temperatures may provide the upland ecotype with additional time to prepare for winter and provide an advantage when plants are subjected to the rapid changes in fall temperature associated with injurious frosts.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Draft Genome Sequences of Switchgrass Diazotrophs

We report the draft genome sequences of five native nitrogen-fixing bacteria associated with roots of switchgrass isolated from the Tallgrass Prairies of Oklahoma. Nitrogen-fixing genes, including the nif cluster, are conserved across the Klebsiella and Kosakonia strains.

Jones, Lauren B.↗
DOE OSTI2022

Transcriptomic Data Sets for Zymomonas mobilis 2032 during Fermentation of Ammonia Fiber Expansion (AFEX)-Pretreated Corn Stover and Switchgrass Hydrolysates

The transcriptomes of Zymomonas mobilis 2032 were captured during the fermentation of ammonia fiber expansion (AFEX)-pretreated corn stover and switchgrass hydrolysates containing different concentrations of glucose and xylose. RNA samples were collected when Z. mobilis was fermenting glucose or xylose. Here, we present transcriptome sequencing (RNA-Seq) data obtained during separate phases of glucose or xylose consumption.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Bacterial isolate collection from switchgrass rhizosphere

ABSTRACT We provide a collection of 78 bacterial isolates from the rhizosphere of switchgrass ( Panicum virgatum L .) at the Lux Arbor Reserve in Delton, MI, a site of the Great Lakes Bioenergy Research Center (GLBRC), Michigan State University, MI, USA. We include information on isolation conditions and full-length 16S rRNA sequences.

Grady, Keara L.↗
DOE OSTI2018

Low-Moisture Switchgrass Bulk-Format Logistics Costs Based on Engineering Data

Abstract. Logistics costs that spanned harvest, transport, storage, preprocessing, and year-round delivery of 371,870 dMg year -1 of milled, low-moisture switchgrass (SG) to a local biorefinery were determined for bulk-format versus round-bale systems. Separate spreadsheet analyses were conducted for three diesel fuel prices ($0.53 L -1 , $0.92 L -1 , and $1.32 L -1 ) because of the wide range of fuel prices during the project. A detailed analysis scenario identified a common harvest period, equipment annual use, other equipment uses, and protected SG storage on gravel pad, along with equipment performances based on previously published tests primarily for commercially available equipment. The bulk-format system used a depot equipped with stacker/reclaimer technology for storage, whereas the round-bale system used field-side bale stacks for storage, with both systems assuming 6% losses, primarily attributed to storage. Results indicated total costs for bulk-format versus round-bale systems of $54.63 per dry Mg (dMg -1 ), $60.41 dMg -1 , and $66.21 dMg -1 versus $54.59 dMg -1 , $62.10 dMg -1 , and $67.93 dMg -1 corresponding with diesel fuel costs of $0.53 L -1 , $0.92 L -1 , and $1.32 L -1 , respectively. The most significant bulk-format system total cost of $22.79 dMg -1 was associated with a stacker/reclaimer, conveyance, and dust collection at the depot, which was 42% of total costs at a diesel fuel cost of $0.53 L -1 . For the round-bale system, bale chopping total costs was highest and represented an average of 27% of total costs, with costs ranging from $14.63 dMg -1 to $19.08 dMg -1 for diesel fuel input costs ranging from $0.53 L -1 to $1.32 L -1 , respectively. For comparison, the forage harvester provided harvesting and chopping in the bulk-format system at total costs ranging from $6.47 dMg -1 to $8.80 dMg -1 across the same range of diesel fuel input cost. The forage harvester provided an economic advantage in size reduction compared to tub grinding. Truck hauling for both the bulk-format and round-bale systems represented significant expenses at all selected fuel costs. In addition, the multiple times that round bales were handled represented accumulating costs that were sensitive to diesel fuel costs. Keywords: Bales, Bioenergy, Bulk format, Densification, Field chop, Logistics, Transportation.

Agriculture↗
DOE OSTI2020

Techno-Economic Impact of Diesel Fuel, Labor, and Interest Rates on Bulk-Format and Round Bale Logistics Expenses for Switchgrass

Highlights System-wide sensitivity of bulk-format and round bale logistics responded to different degrees of expense inputs. Biomass size-reduction expenses for bulk-format were consistently less than round-bale chopping. Stack/reclaim operations with high-density-capacity equipment for bulk-format were the highest expenses. Clean-sheet design of stacker/reclaimer and self-compacting bulk trailer may significantly reduce expenses. Abstract . Deterministic cost analyses were conducted for a harvest, storage, preprocessing, and supply system providing 371,870 dry Mg (dMg) year-1 of milled switchgrass (SG) to a biorefinery from 21,929 ha of production fields within 72 km of the biorefinery. Varied input costs of diesel fuel, labor, and interest rate were input into a highly detailed cost analysis for bulk-format and baseline round bale logistics. These operational input factors, potentially reflecting an evolving economic climate or paradigm shift, were examined to provide insight into the cost to deliver preprocessed biomass feedstock for centralized commercial-scale conversions. Total annual costs per dry unit of SG were determined for all combinations of diesel fuel prices of $0.53 L-1, $0.92 L-1, and $1.32 L-1; total labor costs of $20.00 h-1, $28.85 h-1, and $40.00 h-1 singly and uniformly applied across all labor inputs; and three representative interest rates of 6%, 8%, and 12%. Increases in total cost most depended on increases in diesel fuel cost, followed by labor rate, and finally interest rate. Increases in fuel costs from $0.53 L-1 to $1.32 L-1 yielded a total cost increase of about $11.56 dMg-1 and $13.36 dMg-1 for bulk-format and round bale logistics, respectively, for all combinations of labor and interest rates. The overall increase in labor rate ($20.00 h-1 to $40.85 h-1) resulted in increased total costs of about $10.32 dMg-1 for bulk-format logistics and $9.94 dMg-1 for round bale logistics for all fuel and interest rates. The overall increase in interest rate (6% to 12%) resulted in increased total costs of about $6.72 dMg-1 for bulk-format logistics and $4.21 dMg-1 for round bale logistics for all fuel and labor rates. Increases in total costs for combined increases in fuel cost, labor rate, and interest rate were $28.60 dMg-1 and $27.48 dMg-1, yielding maximum total costs of $87.87 dMg-1 and $86.53 dMg-1 for bulk-format and round bale logistics, respectively. Costs were determined for existing equipment systems, including novel use of waste compaction and ejector semi-trailers. The highest potential for cost reductions may require clean-sheet equipment designs specifically tailored for SG, such as forage harvesters that direct-cut standing SG, mobilized stacker-reclaimer technology to not inhibit stack-area footprint, self-compacting ejector trailer technology, and bale grinding technology incorporating controlled mass feeding and shear failure elements. Keywords: Bales, Bioenergy, Bulk-format, Densification, Field chop, Logistics, Transportation

Agriculture↗
DOE OSTI2013

Proteogenomic Analysis of a Thermophilic Bacterial Consortium Adapted to Deconstruct Switchgrass

Thermophilic bacteria are a potential source of enzymes for the deconstruction of lignocellulosic biomass. However, the complement of proteins used to deconstruct biomass and the specific roles of different microbial groups in thermophilic biomass deconstruction are not well-explored. Here we report on the metagenomic and proteogenomic analyses of a compost-derived bacterial consortium adapted to switchgrass at elevated temperature with high levels of glycoside hydrolase activities. Near-complete genomes were reconstructed for the most abundant populations, which included composite genomes for populations closely related to sequenced strains of Thermus thermophilus and Rhodothermus marinus, and for novel populations that are related to thermophilic Paenibacilli and an uncultivated subdivision of the littlestudied Gemmatimonadetes phylum. Partial genomes were also reconstructed for a number of lower abundance thermophilic Chloroflexi populations. Identification of genes for lignocellulose processing and metabolic reconstructions suggested Rhodothermus, Paenibacillus and Gemmatimonadetes as key groups for deconstructing biomass, and Thermus as a group that may primarily metabolize low molecular weight compounds. Mass spectrometry-based proteomic analysis of the consortium was used to identify .3000 proteins in fractionated samples from the cultures, and confirmed the importance of Paenibacillus and Gemmatimonadetes to biomass deconstruction. These studies also indicate that there are unexplored proteins with important roles in bacterial lignocellulose deconstruction.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2019

Extensions of BLUP Models for Genomic Prediction in Heterogeneous Populations: Application in a Diverse Switchgrass Sample

Genomic prediction is a useful tool to accelerate genetic gain in selection using DNA marker information. However, this technology typically relies on standard prediction procedures, such as genomic BLUP, that are not designed to accommodate population heterogeneity resulting from differences in marker effects across populations. In this study, we assayed different prediction procedures to capture marker-by-population interactions in genomic prediction models. Prediction procedures included genomic BLUP and two kernel-based extensions of genomic BLUP which explicitly accounted for population heterogeneity. To model population heterogeneity, dissemblance between populations was either depicted by a unique coefficient (as previously reported), or a more flexible function of genetic distance between populations (proposed herein). Models under investigation were applied in a diverse switchgrass sample under two validation schemes: whole-sample calibration, where all individuals except selection candidates are included in the calibration set, and cross-population calibration, where the target population is entirely excluded from the calibration set. First, we showed that using fixed effects, from principal components or putative population groups, appeared detrimental to prediction accuracy, especially in cross-population calibration. Then we showed that modelling population heterogeneity by our proposed procedure resulted in highly significant improvements in model fit. In such cases, gains in accuracy were often positive. These results suggest that population heterogeneity may be parsimoniously captured by kernel methods. However, in cases where improvement in model fit by our proposed procedure is null-to-moderate, ignoring heterogeneity should probably be preferred due to the robustness and simplicity of the standard genomic BLUP model.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

AmeriFlux US-UiA University of Illinois Switchgrass

This is the AmeriFlux version of the carbon flux data for the site US-UiA University of Illinois Switchgrass. Site Description - Field was treated with Potash, lime and diammonium phosphate before planting. Herbicide application included 2,4-D for 2008, 2009. 56 kg/ha nitrogen applied in 2010, 2011, 2012, 2013, 2014, 2016. Measurements were suspended on June 14, 2016 and resumed on May 28, 2024.

Bernacchi, Carl↗
DOE OSTI2022

GLBRC_Switchgrass_2018_Microbiome

Data for the manuscript Bell-Dereske et al. Variation in root and soil microbiome over space and time in a single plant host. Bacterial and fungal communities from switchgrass roots and soils.

Bell-Dereske, Lukas P.↗
DOE OSTI2013

Space‐Plant versus Sward‐Plot Evaluation of Half‐Sib Families to Select Parents for Synthetic Cultivars with Superior Biomass Yield in Lowland Switchgrass

ABSTRACT Switchgrass ( Panicum virgatum L.) needs significant biomass yield improvement for its viable use as bioenergy feedstock. Conventional family evaluation under sward plot is very effective in cultivar improvement, but it is time and resource consuming. Family evaluation under space planting using honeycomb design can reduce time and inputs. The objective of this study was to compare conventional sward‐plot and modified space‐plant evaluation of half‐sib families in their biomass yield gain and resource use. Using same initial set of genotypes selected from ‘Alamo’, two experimental synthetics were developed by the following methods: (i) summer field polycrossing of selected genotypes to produce half‐sibs, half‐sib family evaluation under sward plot conditions (HSSward) at two locations for 2 yr, and polycrossing the five genotypes showing superior half‐sibs to produce the experimental and (ii) greenhouse polycrossing genotypes during the winter to produce half‐sibs, half‐sib family evaluation under space‐plant conditions using honeycomb design (HSSpace) for 2 yr at one location, and polycrossing the five best progeny within the five superior half‐sibs to produce the experimental. The 2 to 3 yr biomass yield performance of two experimentals across five locations demonstrated that both HSSward and HSSpace led to a significant biomass yield gain over Alamo in three and two of the five locations, respectively. The HSSward produced a superior and more stable synthetic across a wide region than HSSpace. However, the HSSpace produced its synthetic a year sooner and was more resource efficient and, under finite resources, it could be a method of choice for cultivar development especially for a narrow geographic region.

Bhandari, H. S.↗