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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Overexpression of patatin-related phospholipase AIIIδ altered plant growth and increased seed oil content in camelina

Camelina sativa is a Brassicaceae oilseed species being explored as a biofuel and industrial oil crop. A growing number of studies have indicated that the turnover of phosphatidylcholine plays an important role in the synthesis and modification of triacylglycerols. This study manipulated the expression of a patatin-related phospholipase AIIIδ ( pPLAIIIδ ) in camelina to determine its effect on seed oil content and plant growth. Constitutive overexpression of pPLAIIIδ under the control of the constitutive cauliflower mosaic 35S promoter resulted in a significant increase in seed oil content and a decrease in cellulose content. In addition, the content of major membrane phospholipids, phosphatidylcholine and phosphatidylethanolamine, in 35S::pPLAIIIδ plants was increased. However, these changes in 35S::pPLAIIIδ camelina were associated with shorter cell length, leaves, stems, and seed pods and a decrease in overall seed production. When pPLAIIIδ was expressed under the control of the seed specific, β-conglycinin promoter, the seed oil content was increased without compromising plant growth. In conclusion, the results suggest that pPLAIIIδ alters the carbon partitioning by decreasing cellulose content and increasing oil content in camelina.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Arabidopsis plants expressing only the redox–regulated Rca–α isoform have constrained photosynthesis and plant growth

Rubisco activase (Rca) facilitates the release of sugar–phosphate inhibitors from the active sites of Rubisco and thereby plays a central role in initiating and sustaining Rubisco activation. In Arabidopsis, alternative splicing of a single Rca gene results in two Rca isoforms, Rca–α and Rca–β. Redox modulation of Rca–α regulates the function of Rca–α and Rca–β acting together to control Rubisco activation. Although Arabidopsis Rca–α alone less effectively activates Rubisco in vitro, it is not known how CO 2 assimilation and plant growth are impacted. Here, we show that two independent transgenic Arabidopsis lines expressing Rca–α in the absence of Rca–β (‘Rca–α only’ lines) grew more slowly in various light conditions, especially under low light or fluctuating light intensity, and in a short day photoperiod compared to wildtype. Photosynthetic induction was slower in the Rca–α only lines, and they maintained a lower rate of CO 2 assimilation during both photoperiod types. Here, our findings suggest Rca oligomers composed of Rca–α only are less effective in initiating and sustaining the activation of Rubisco than when Rca–β is also present. Currently there are no examples of any plant species that naturally express Rca–α only but numerous examples of species expressing Rca–β only. That Rca–α exists in most plant species, including many C3 and C4 food and bioenergy crops, implies its presence is adaptive under some circumstances.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Feasibility studies to improve plant availability and reduce total installed cost in IGCC plants

The main purpose of this project is to look at technologies and philosophies that would help reduce the costs of an Integrated Gasification Combined Cycle (IGCC) plant, increase its availability or do both. GE’s approach to this problem is to consider options in three different areas: 1) technology evaluations and development; 2) constructability approaches; and 3) design and operation methodologies. Five separate tasks were identified that fall under the three areas: Task 2 – Integrated Operations Philosophy; Task 3 – Slip Forming of IGCC Components; Task 4 – Modularization of IGCC Components; Task 5 – Fouling Removal; and Task 6 – Improved Slag Handling. Overall, this project produced results on many fronts. Some of the ideas could be utilized immediately by those seeking to build an IGCC plant in the near future. These include the considerations from the Integrated Operations Philosophy task and the different construction techniques of Slip Forming and Modularization (especially if the proposed site is in a remote location or has a lack of a skilled workforce). Other results include ideas for promising technologies that require further development and testing to realize their full potential and be available for commercial operation. In both areas GE considers this project to be a success in identifying areas outside the core IGCC plant systems that are ripe for cost reduction and ity improvement opportunities.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2017

Soil-mediated effects of global change on plant communities depend on plant growth form

Understanding why species respond to climate change is critical for forecasting invasions, diversity, and productivity of communities. Although researchers often predict species’ distributions and productivity based on direct physiological responses to environments, theory suggests that striking shifts in community composition could arise if global change alters indirect feedbacks mediated by resources, mutualists, or antagonists. To test whether global change influences plant communities via soil–mediated feedbacks, we grew model communities in soils collected from a seven–year field manipulation of CO 2 , warming, and invasion. We evaluated mechanisms underlying variation in the model communities by comparing species’ growth in equivalent soil histories with, and without, experimentally reduced soil biota (via sterilization) and nutrient limitation (via fertilization). We show that grasses performed consistently across all soil history scenarios and that soil biota limited grasses more than nutrients. In contrast, forbs were differentially sensitive to soil history scenarios, with the magnitude and direction of responses to soil biota and nutrients dependent upon plant species and global change scenario. The asymmetry in importance of soil history for grasses and forbs is likely explained by differences in life history strategy. We conclude that accounting for species’ growth strategies will improve predictions of species sensitivity to altered soil feedbacks in future climates.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Data for An Orphan Gene BOOSTER Enhances Photosynthetic Efficiency and Plant Productivity

Seeds of Col-0 wild type, sig6 T-DNA mutants (CS877785, ABRC), PRL-1-OE, and sig6 T-DNA mutants transfected with PRL-1 (sig6::PRL-1) were planted in 1/2 MS media. Seedlings growth including chlorophyll development defects were investigated across the genotypes. Four-days-old-post-light exposure seedlings were harvested and performed RNAseq analysis with four biological replicates.

Biomass Analytics↗
DOE OSTI2019

A Field Survey of Rare Earth Element Concentrations in Process Streams Produced by Coal Preparation Plants in the Eastern USA

I this work, a field study was undertaken to experimentally measure the concentrations of rare earth elements (REEs) contained in the process streams generated by a group of 20 coal preparation plants located in the eastern USA. For each site, representative samples of clean coal product, coarse refuse, and fine refuse were collected. Each sample was then partitioned into preselected size and density classes by wet screening/sieving and float-sink testing. The resultant products were dried and subjected to laboratory analyses to determine ash contents and rare earth element concentrations including Yttrium and Scandium. A detailed analysis of the database generated by this exercise showed that coal-based products from these preparation plants contained significant quantities of rare earth elements. In particular, the coarse refuse streams currently discarded by the 20 plants examined were found to contain a sufficient tonnage of REEs to satisfy the current domestic demand for these important elements. The data also showed a strong positive correlation between ash content and REE concentration, which suggested that the primary association of REEs in eastern USA bituminous coal sources is likely within fractions containing inorganic impurities. This association was well described using a simple power equation relating ash content and REE concentration. The ratio of heavy-to-light rare earth elements was discovered to be significantly higher in organically rich fractions of clean coal, suggesting that mineral impurities intimately associated with carbonaceous matter have elevated concentrations of heavy rare earth elements. A similar trend was observed for a grouping of rare earth elements (Y, Nd, Eu, Tb, and Dy) that are likely subject to near-term supply shortages. Finally, the database showed that a linear correlation existed between La for many REEs of interest, although there were several notable exceptions for some high-value REEs (Lu, Pr, and Tb).

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2015

Evolution of plant virus movement proteins from the 30K superfamily and of their homologs integrated in plant genomes

Homologs of Tobacco mosaic virus 30K cell-to-cell movement protein are encoded by diverse plant viruses. Mechanisms of action and evolutionary origins of these proteins remain obscure. We expand the picture of conservation and evolution of the 30K proteins, producing sequence alignment of the 30K superfamily with the broadest phylogenetic coverage thus far and illuminating structural features of the core all-beta fold of these proteins. Integrated copies of pararetrovirus 30K movement genes are prevalent in euphyllophytes, with at least one copy intact in nearly every examined species, and mRNAs detected for most of them. Sequence analysis suggests repeated integrations, pseudogenizations, and positive selection in those provirus genes. An unannotated 30K-superfamily gene in Arabidopsis thaliana genome is likely expressed as a fusion with the At1g37113 transcript. This molecular background of endopararetrovirus gene products in plants may change our view of virus infection and pathogenesis, and perhaps of cellular homeostasis in the hosts. - Highlights: • Sequence region shared by plant virus “30K” movement proteins has an all-beta fold. • Most euphyllophyte genomes contain integrated copies of pararetroviruses. • These integrated virus genomes often include intact movement protein genes. • Molecular evidence suggests that these “30K” genes may be selected for function.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Anisotropic Motions of Fibrils Dictated by Their Orientations in the Lamella: A Coarse-Grained Model of a Plant Cell Wall

Plant cell walls are complex systems that exhibit the characteristics of both rigid and soft material depending on their external perturbations. The three main polymeric components in a plant primary cell wall are cellulose fibrils, hemicellulose, and pectins. These components interact in a hierarchical fashion giving rise to mesoscale structural features such as cellulose bundles, lamella stacking, and so on. Although several studies have focused on understanding these unique structural features, a clear picture linking them to cell wall mechanics is still lacking. As a first step toward this goal, a phenomenological model of plant cell wall has been developed in this work by using available experimental data to investigate the underlying connections between mesoscale structural features and the motions of fibrils during deformation. In this model cellulose fibrils exhibit motions such as angular reorientations and kinking upon forced stretching. Furthermore, these motions are dependent on the orientation of fibrils with respect to the stretch direction, i.e., fibrils that are at an angle to the stretch direction exhibit predominant angular reorientations, while fibrils transverse to the stretch direction undergo kinking as a result of transverse compression. Varying the chain length of pectin had negligible effects on these motions. One of the main contributions from this work is the development of a simple model that can be easily fine-tuned to test other hypotheses and extended to include additional experimental knowledge about the structural aspects of cell walls in the future.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Diverse MarR bacterial regulators of auxin catabolism in the plant microbiome

Abstract Chemical signalling in the plant microbiome can have drastic effects on microbial community structure, and on host growth and development. Previously, we demonstrated that the auxin metabolic signal interference performed by the bacterial genus Variovorax via an auxin degradation locus was essential for maintaining stereotypic root development in an ecologically relevant bacterial synthetic community. Here, we dissect the Variovorax auxin degradation locus to define the genes iadDE as necessary and sufficient for indole-3-acetic acid (IAA) degradation and signal interference. We determine the crystal structures and binding properties of the operon’s MarR-family repressor with IAA and other auxins. Auxin degradation operons were identified across the bacterial tree of life and we define two distinct types on the basis of gene content and metabolic products: iac -like and iad -like. The structures of MarRs from representatives of each auxin degradation operon type establish that each has distinct IAA-binding pockets. Comparison of representative IAA-degrading strains from diverse bacterial genera colonizing Arabidopsis plants show that while all degrade IAA, only strains containing iad -like auxin-degrading operons interfere with auxin signalling in a complex synthetic community context. This suggests that iad -like operon-containing bacterial strains, including Variovorax species, play a key ecological role in modulating auxins in the plant microbiome.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

Long-term exposure to elevated CO 2 enhances plant community stability by suppressing dominant plant species in a mixed-grass prairie

Climate controls vegetation distribution across the globe, and some vegetation types are more vulnerable to climate change, whereas others are more resistant. Because resistance and resilience can influence ecosystem stability and determine how communities and ecosystems respond to climate change, we need to evaluate the potential for resistance as we predict future ecosystem function. In a mixed-grass prairie in the northern Great Plains, in this study we used a large field experiment to test the effects of elevated CO 2 , warming, and summer irrigation on plant community structure and productivity, linking changes in both to stability in plant community composition and biomass production. We show that the independent effects of CO 2 and warming on community composition and productivity depend on interannual variation in precipitation and that the effects of elevated CO 2 are not limited to water saving because they differ from those of irrigation. We also show that production in this mixed-grass prairie ecosystem is not only relatively resistant to interannual variation in precipitation, but also rendered more stable under elevated CO 2 conditions. This increase in production stability is the result of altered community dominance patterns: Community evenness increases as dominant species decrease in biomass under elevated CO 2 . In many grasslands that serve as rangelands, the economic value of the ecosystem is largely dependent on plant community composition and the relative abundance of key forage species. Finally, our results have implications for how we manage native grasslands in the face of changing climate.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Bacterial, fungal, and plant communities exhibit no biomass or compositional response to two years of simulated nitrogen deposition in a semiarid grassland: Bacterial, fungal, and plant communities

Nitrogen (N) deposition affects myriad aspects of terrestrial ecosystem structure and function, and microbial communities may be particularly sensitive to anthropogenic N inputs. However, our understanding of N deposition effects on microbial communities is far from complete, especially for drylands where data are comparatively rare. To address the need for an improved understanding of dryland biological responses to N deposition, we conducted a two-year fertilization experiment in a semiarid grassland on the Colorado Plateau in the southwestern United States. We evaluated effects of varied levels of N inputs on archaeal, bacterial, fungal and chlorophyte community composition within three microhabitats: biological soil crusts (biocrusts), soil below biocrusts, and the plant rhizosphere. Surprisingly, N addition did not affect the community composition or diversity of any of these microbial groups; however, microbial community composition varied significantly among sampling microhabitats. Further, while plant richness, diversity, and cover showed no response to N addition, there were strong linkages between plant properties and microbial community structure. Overall, these findings highlight the potential for some dryland communities to have limited biotic ability to retain augmented N inputs, possibly leading to large N losses to the atmosphere and to aquatic systems.

59 BASIC BIOLOGICAL SCIENCES↗