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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Influence of microgravity on cellular differentiation in root caps of Zea mays

We launched imbibed seeds of Zea mays into outer space aboard the space shuttle Columbia to determine the influence of microgravity on cellular differentiation in root caps. The influence of microgravity varied with different stages of cellular differentiation. Overall, microgravity tended to 1) increase relative volumes of hyaloplasm and lipid bodies, 2) decrease the relative volumes of plastids, mitochondria, dictyosomes, and the vacuome, and 3) exert no influence on the relative volume of nuclei in cells comprising the root cap. The reduced allocation of dictyosomal volume in peripheral cells of flight-grown seedlings correlated positively with their secretion of significantly less mucilage than peripheral cells of Earth-grown seedlings. These results indicate that 1) microgravity alters the patterns of cellular differentiation and structures of all cell types comprising the root cap, and 2) the influence of microgravity on cellular differentiation in root caps of Zea mays is organelle specific.

NASA Program Space Biology↗
NASA NTRS1988

The habits of roots: what's up down under?

Defining interactions of roots with the surrounding soil environment has been the focus of many recent investigations. As a result of these efforts, we are gaining an appreciation of the varied and often surprising strategies whereby roots adjust to and condition their soil environment for optimal growth and development. This article summarizes current knowledge of the often complex interactions between roots and biotic and abiotic factors within the soil. These interactions are interpreted in terms of modifications in the development or the physiology of the root.

Review↗
NASA NTRS1984

Effects of light on protein patterns in gravitropically stimulated root caps of corn

In certain cultivars of corn (Zea mays var. Merit), light stimulates gravitropic bending of the root by influencing events in the root cap. In this paper, we report on changes in root cap proteins which occur as a result of the light treatment and single out specific proteins as potentially having a role in mediating the gravitropic response. For this work, we have used root caps maintained aseptically in culture media supplemented with auxin. If auxin is deleted from the culture medium, the protein profiles observed following illumination differ from that seen in caps provided light while in auxin-supplemented media. We also report that several of the proteins for which synthesis is stimulated by light appear to turn over rapidly, usually within 0.5 hour of formation.

Gravitropism/physiology/radiation effects↗
DOE OSTI2011

A specialist root herbivore exploits defensive metabolites to locate nutritious tissues

The most valuable organs of plants are often particularly rich in essential elements, but also very well defended. This creates a dilemma for herbivores that need to maximise energy intake while minimising intoxication. We investigated how the specialist root herbivore Diabrotica virgifera solves this conundrum when feeding on wild and cultivated maize plants. We found that crown roots of maize seedlings were vital for plant development and, in accordance, were rich in nutritious primary metabolites and contained higher amounts of the insecticidal 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and the phenolic compound chlorogenic acid. The generalist herbivores Diabrotica balteata and Spodoptera littoralis were deterred from feeding on crown roots, whereas the specialist D. virgifera preferred and grew best on these tissues. Using a 1,4-benzoxazin-3-one-deficient maize mutant, we found that D. virgifera is resistant to DIMBOA and other 1,4-benzoxazin-3-ones and that it even hijacks these compounds to optimally forage for nutritious roots.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Self‐gated, dynamic contrast‐enhanced magnetic resonance imaging with compressed‐sensing reconstruction for evaluating endothelial permeability in the aortic root of atherosclerotic mice

High‐risk atherosclerotic plaques are characterized by active inflammation and abundant leaky microvessels. We present a self‐gated, dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) acquisition with compressed sensing reconstruction and apply it to assess longitudinal changes in endothelial permeability in the aortic root of Apoe −/− atherosclerotic mice during natural disease progression. Twenty‐four, 8‐week‐old, female Apoe −/− mice were divided into four groups (n = 6 each) and imaged with self‐gated DCE‐MRI at 4, 8, 12, and 16 weeks after high‐fat diet initiation, and then euthanized for CD68 immunohistochemistry for macrophages. Eight additional mice were kept on a high‐fat diet and imaged longitudinally at the same time points. Aortic‐root pseudo‐concentration curves were analyzed using a validated piecewise linear model. Contrast agent wash‐in and washout slopes ( b 1 and b 2 ) were measured as surrogates of aortic root endothelial permeability and compared with macrophage density by immunohistochemistry. b 2 , indicating contrast agent washout, was significantly higher in mice kept on an high‐fat diet for longer periods of time ( p = 0.03). Group comparison revealed significant differences between mice on a high‐fat diet for 4 versus 16 weeks ( p = 0.03). Macrophage density also significantly increased with diet duration ( p = 0.009). Spearman correlation between b 2 from DCE‐MRI and macrophage density indicated a weak relationship between the two parameters (r = 0.28, p = 0.20). Validated piecewise linear modeling of the DCE‐MRI data showed that the aortic root contrast agent washout rate is significantly different during disease progression. Further development of this technique from a single‐slice to a 3D acquisition may enable better investigation of the relationship between in vivo imaging of endothelial permeability and atherosclerotic plaques' genetic, molecular, and cellular makeup in this important model of disease.

Calcagno, Claudia↗
DOE OSTI2024

Contrasting roles of rice root iron plaque in retention and plant uptake of silicon, phosphorus, arsenic, and selenium in diverse paddy soils

Abstract Background and aims Iron (Fe) plaque on rice roots is a mixture of Fe oxide and oxyhydroxide minerals thought to protect rice from high levels of arsenic (As) in flooded paddy soils. Silicon (Si), phosphorus (P), and selenium (Se) also exist as oxyanions in rice paddies, but the impacts of Fe plaque on uptake of these nutrients are unknown. Methods We used natural variation in paddy soil chemistry to test how Si, P, As, and Se move from porewater to plaque to plant via multiple techniques. In a pot study, we monitored Fe plaque deposition and porewater chemistry in 5 different soils over time and measured plaque/plant chemistry and Fe plaque mineralogy at harvest. We normalized oxyanion concentrations by Fe to determine the preferential retention on plaque or plant uptake. Results Low phosphorus availability increased root Fe-oxidizing activity, while Fe, Si, P, As, and Se concentrations in plaque were strongly correlated with porewater. Plaque did not appreciably retain Si and Se, and the oxyanions did not compete for adsorption sites on the Fe plaque. Conclusion Root Fe plaque seems to protect rice from As uptake, does not interfere with Si and Se uptake, and roots adapt to maintain P nutrition even with retention of porewater P on plaque.

Agriculture↗
DOE OSTI2024

Plant-specific microbial diversity facilitates functional redundancy at the soil-root interface

Abstract Aims Plant-specific microbial diversity reflecting host-microbe coevolution was frequently shown at the structural level but less on the functional scale. We studied the microbiome of three compartments at the soil root interface (root endosphere, rhizosphere, bulk soil) of medicinal plants cultivated under organic management in Egypt. The study aimed to examine the impact of the rhizosphere on microbial community composition and diversity in desert agricultural soil, as well as to identify specific functions associated with the rhizosphere. Methods The microbiome community structure, diversity, and microbial functioning were evaluated through the utilization of 16S rRNA gene amplicon and shotgun metagenome sequencing. Results We found the typical rhizosphere effect and plant-species-specific enrichment of bacterial diversity. The annual plants Calendula officinalis and Matricaria chamomilla ( Asteraceae ) were more similar than the perennial Solanum distichum ( Solanaceae ). Altogether, plant species explained 50.5% of the variation in bacterial community structures in the rhizosphere. Our results indicate a stronger effect of the plant species in terms of modulating bacterial community structures in the rhizosphere than in root endosphere samples. The plant-driven rhizosphere effect could be linked to redundant plant beneficial functions in the microbiome, while enrichment of specific genes related to amino acid ion transport and metabolism, carbohydrate transport and metabolism, defense mechanisms, and secondary metabolites biosynthesis were more specific. Conclusions The study explores the microbiome continuum at the soil-root interface of medicinal plant species, revealing significant bacterial community structure shifts and plant specificity. The study provides insights into the essential microbiome components contributing to rhizosphere functionality.

Wicaksono, Wisnu Adi (ORCID:0000000215561981)↗
DOE OSTI2016

Detection of phosphate transporter genes from arbuscular mycorrhizal fungi in mature tree roots under experimental soil pH manipulation

We present the majority of terrestrial plant roots are colonized by arbuscular mycorrhizal (AM) fungi that, in exchange for carbon, provide plants with enhanced nutrient uptake — most notably inorganic phosphate (P i ). To mediate the uptake of Pi from the soil, AM fungi possess high affinity inorganic phosphate transporters (PTs). Under laboratory conditions, P i concentrations have been shown to regulate AM fungal-specific PT gene expression. The relationship between PT expression and P i in the field remains unexplored. Here we quantify AM fungal-specific PTs from maple tree roots in situ. In an effort to limit edaphic parameters, root samples were collected from manipulated forested plots that had elevated soil P i availability, either through direct P i application or elevating pH to lower exchangeable aluminum. The aim of the study was to examine AM fungal-specific PT gene expression both prior to and following soil P i amendment; however, a direct correlation between soil P i concentration and PT gene expression was not observed. PT transcripts were detected to a greater extent under elevated pH and, while our results are confounded by an overall low detection of PT genes (23 % of all samples collected), our findings raise interesting questions regarding the role of soil pH on PT function. In conclusion, our study is a first step in understanding how edaphic properties influence PT expression and plant P acquisition in mature tree roots.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Soil organic matter is principally root derived in an Ultisol under oak forest

To a large degree, the sources and stability of soil organic carbon remain poorly constrained. A clear understanding of links among the components of the soil C cycle is hampered by the complexity of the system as well as challenges associated with partitioning bulk soil C into meaningful fractions. A large accidental 14 CO 2 release at the Oak Ridge Reservation in Tennessee, USA provided a strong label pulse into adjacent, well-studied oak forests, resulting in highly elevated Δ 14 C values in leaf litter (~1000‰) and roots (~260–450‰). A four-year manipulative study was conducted to determine the relative contribution of litter versus roots to the bulk mineral soil C pool, as well as to free light, occluded light and heavy fractions. The heavy fraction was further split into fractions with densities of 1.7–2.4 g cm –3 and >2.4 g cm –3 to test the homogeneity of the mineral-associated fraction of C. Substantial concentrations of label were detected in all soil fractions within a year of the 14 CO 2 release, indicating rapid incorporation of newly fixed photosynthates in all fractions of soil organic C, regardless of differences in stability inferred by previous work. This rapid incorporation of label occurred only in treatments where roots were labeled, indicating that roots are the major source of inputs to mineral soil C stocks at these sites. Separation of the heavy fraction into subfractions of intermediate (1.7–2.4 g cm –3 ) and high (>2.4 g cm –3 ) density indicated that both subfractions incorporated label at similar rates, despite significant differences in degree of microbial processing. In general, the rate of label incorporation suggested a much faster turnover for all fractions than indicated by natural radiocarbon abundance values. This study suggests that within each soil fraction there are portions of slow-cycling and fast-cycling materials, and the determination of an average turnover time or mean age is dependent on experimental approach. The rapid incorporation of label into all fractions within a year regardless of inferred stability implies a high degree of heterogeneity in all fractions regardless of how finely the soils are partitioned. Further refinement of the nature and drivers of this heterogeneity could yield important insights into the soil C cycle.

58 GEOSCIENCES↗
DOE OSTI2022

Soil compartments (bulk soil, litter, root and rhizosphere) as main drivers of soil protistan communities distribution in forests with different nitrogen deposition

Protists, in particular bacterivores, are essential players in the rhizosphere; thus, how their interactions with bacteria and fungi affect plant productivity and soil nutrient cycles warrants more attention. Using next-generation sequencing of the 18 S rRNA gene, we investigated the distribution of two major protistan phyla, Cercozoa and Endomyxa, across four seasons, and four soil compartments - rhizosphere, root, soil and litter. The sampling was replicated in two forests in Norway and the Czech Republic, in order to test our results across biogeographic scales. Compartment had a major influence in shaping protistan communities, over and above spatial distance and seasonal variation. Protistan diversity was highest in the bulk soil while lowest in the roots, suggesting that the plants select for restricted assemblages of protists. Accordingly, only the root compartment harboured a subset of the bulk soil protistan diversity. In addition, protistan communities showed markedly different distributions according to their feeding modes, with opposite patterns for bacterivores versus omnivores and eukaryvores. The small bacterivorous flagellates (mostly Glissomonadida) were more abundant in roots, while the larger amoeboid eukaryvores (e.g. some of the Cryomonadida and vampyrellids) dominated in soil and in the rhizosphere, and the omnivores (e.g. Euglyphida and part of the Cercomonadida), also large and mostly amoeboid, were more abundant in litter. The current view of the soil microbiome is mostly focused on bacteria and fungi: this detailed study on the community distribution of protists according to their feeding modes reveals the essential role they play in each of the soil compartments, an essential precondition for a detailed understanding of the soil food web and nutrient cycling in forest.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

In Situ Detection of Amino Acids from Bacterial Biofilms and Plant Root Exudates by Liquid Microjunction Surface-Sampling Probe Mass Spectrometry

The plant rhizosphere is a complex and dynamic chemical environment where the exchange of molecular signals between plants, microbes, and fungi drives the development of the entire biological system. Exogenous compounds in the rhizosphere are known to affect plant-microbe organization, interactions between organisms, and ultimately, growth and survivability. The function of exogenous compounds in the rhizosphere is still under much investigation, specifically with respect to their roles in plant growth and development, the assembly of the associated microbial community, and the spatiotemporal distribution of molecular components. A major challenge for spatiotemporal measurements is developing a nondisruptive and nondestructive technique capable of analyzing the exogenous compounds contained within the environment. A methodology using liquid microjunction-surface sampling probe-mass spectrometry (LMJ-SSP-MS) and microfluidic devices with attached microporous membranes was developed for in situ, spatiotemporal measurement of amino acids (AAs) from bacterial biofilms and plant roots. Exuded arginine was measured from a living Pantoea YR 343 biofilm, which resulted in a chemical image indicative of biofilm growth within the device. Spot sampling along the roots of Populus trichocarpa with the LMJ-SSP-MS resulted in the detection of 15 AAs. Of note, variation in AA concentrations across the root system was observed, indicating that exudation is not homogeneous and may be linked to local rhizosphere architecture and different biological processes along the root.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Deep Roots Supply Reactivity and Enhance Silicate Weathering in the Bedrock Vadose Zone

In upland environments, roots commonly extend deep below soil into partially saturated bedrock. This Bedrock Vadose Zone (BVZ) has been shown to store and circulate water, host organic carbon respiration and serve as a critical source of rock-derived nutrients. However, the extent to which deep roots influence chemical weathering rates remains poorly understood. Here, we report 4 years of depth-resolved major ion chemistry over a 16-m thick BVZ hosting a deep rhizosphere in a catchment subject to a Mediterranean climate. These data allow development and validation of a reactive transport model (RTM), revealing that the timescales of water storage and drainage in the BVZ are sufficient to facilitate substantial chemical weathering of the shale bedrock. However, observed solute concentrations are only reproduced by the RTM when we explicitly include measured rates of CO 2(g) production meters below soil driven by the deeply rooted forest. By combining direct observations and a process-based RTM we conclude that the carbon respiration promoted by deep roots significantly enhances chemical weathering rates in the BVZ, constituting 43% ± 3% of total solute flux from the base of the BVZ to the water table.

Osorio‐Leon, Ivan D. [University of Illinois Urban↗
DOE OSTI2016

Host genotype and age shape the leaf and root microbiomes of a wild perennial plant

Bacteria living on and in leaves and roots influence many aspects of plant health, so the extent of a plant's genetic control over its microbiota is of great interest to crop breeders and evolutionary biologists. Laboratory-based studies, because they poorly simulate true environmental heterogeneity, may misestimate or totally miss the influence of certain host genes on the microbiome. Here we report a large-scale field experiment to disentangle the effects of genotype, environment, age and year of harvest on bacterial communities associated with leaves and roots of Boechera stricta (Brassicaceae), a perennial wild mustard. Host genetic control of the microbiome is evident in leaves but not roots, and varies substantially among sites. Microbiome composition also shifts as plants age. Furthermore, a large proportion of leaf bacterial groups are shared with roots, suggesting inoculation from soil. Our results demonstrate how genotype-by-environment interactions contribute to the complexity of microbiome assembly in natural environments.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Choreographing root architecture and rhizosphere interactions through synthetic biology

Abstract Climate change is driving extreme changes to the environment, posing substantial threats to global food security and bioenergy. Given the direct role of plant roots in mediating plant-environment interactions, engineering the form and function of root systems and their associated microbiota may mitigate these effects. Synthetic genetic circuits have enabled sophisticated control of gene expression in microbial systems for years and a surge of advances has heralded the extension of this approach to multicellular plant species. Targeting these tools to affect root structure, exudation, and microbe activity on root surfaces provide multiple strategies for the advancement of climate-ready crops.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

A Parallelised ROOT for Future HEP Data Processing

In the coming years, HEP data processing will need to exploit parallelism on present and future hardware resources to sustain the bandwidth requirements. As one of the cornerstones of the HEP software ecosystem, ROOT embraced an ambitious parallelisation plan which delivered compelling results. In this contribution the strategy is characterised as well as its evolution in the medium term. The units of the ROOT framework are discussed where task and data parallelism have been introduced, with runtime and scaling measurements. We will give an overview of concurrent operations in ROOT, for instance in the areas of I/O (reading and writing of data), fitting / minimization, and data analysis. This paper introduces the programming model and use cases for explicit and implicit parallelism, where the former is explicit in user code and the latter is implicitly managed by ROOT internally.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Thoroughly testing and integrating hundreds of Pull Requests per month: ROOT’s new Cost-efficient and Feature Rich GitHub-based CI

ROOT is an open source framework, freely available on GitHub, at the heart of data acquisition, processing and analysis of HE(N)P experiments, and beyond. It is developed collaboratively: contributions are not authored only by ROOT team members, but also by the user community at large: developers and scientists from universities, labs as well as the private sector. More than 1500 GitHub Pull Requests are merged on average per year. It is in this context that code integration acquires a primary role. The review of code contributions isn’t enough: not only they need to be thoroughly reviewed, they also need to be thoroughly tested through a powerful CI infrastructure on several different platforms to comply with the high code quality standards of the project. Since the end of 2023, ROOT moved its continuous integration system from Jenkins to GitHub Actions. In this contribution, we characterise the transition to the GitHub CI, focussing on our strategy, its implementation and the lessons learned, as well as the advantages the new system offers with respect to the previous one. Particular emphasis will be given to the evaluation of the cost-benefit ratio for Jenkins and GitHub Actions for the ROOT project. We also describe how we manage to run in less than one hour thousands of unit, integration, functional and end-to-end tests on different flavours of Windows, four versions of macOS, as well as about ten of the most used Linux distributions, taking advantage of the CERN computing infrastructure.

Piparo, Danilo [CERN]↗
DOE OSTI2020

Investigation of the neoclassical ambipolar electric field in ion-root plasmas on W7-X

The role of the radial electric field in high-performance ion-root plasmas on Wendelstein 7-X (W7-X) is examined and compared with neoclassical predictions herein. The W7-X stellarator is the world’s first large-scale optimized stellarator. One of the important targets chosen for optimization during the W7-X design process was the reduction of core neoclassical heat transport. This optimization was targeted for reactor-relevant high-density plasmas with $T_e ≈ T_i$ in which the neoclassical ambipolar radial electric field is expected to be negative throughout the plasmas core. Measurements of the core radial electric field $(E_r)$ have confirmed that ion-root conditions (negative $(E_r)$ in the plasma core) have been achieved in W7-X with high-density plasmas and central ECRH. These measured $(E_r)$ profiles agree well with the neoclassical ambipolar $(E_r)$ predicted by the code SFINCS . This good agreement provides confidence in the validity of neoclassical calculations in high-density ion-root conditions, and enables initial studies on the role of neoclassical transport in the optimized high-density regime of W7-X. Profile measurements of electron temperature $(T_e)$, ion temperature $(T_i)$ and electron density $(n_e)$ along with approximations for the average value of $Z$ eff have been used as inputs to the sfincs code to calculate the ambipolar $E_r$ profile along with neoclassical ion and electron energy flux profiles $(Q$ NCi , $Q$ NCe $)$. Finally the total experimental energy input to the plasma from ECRH heating has been compared to the neoclassical energy fluxes to provide a first estimate for the fraction of transport that can be attributed to neoclassical processes in reactorrelevant high-density ion-root conditions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

A Divergent Clade KAI2 Protein in the Root Parasitic Plant Orobanche minor Is a Highly Sensitive Strigolactone Receptor and Is Involved in the Perception of Sesquiterpene Lactones

Abstract Strigolactones (SLs) were initially discovered as germination inducers for root parasitic plants. In 2015, three groups independently reported the characterization of the SL receptor in the root parasitic plant Striga hermonthica, which causes significant damage to crop production, particularly in sub-Saharan Africa. The characterized receptors belong to HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE2 (HTL/KAI2), which is a member of the α/β-hydrolase protein superfamily. In non-parasitic plants, HTL/KAI2 perceives the smoke-derived germination inducer karrikin and a yet-unidentified endogenous ligand. However, root parasitic plants evolved a specific clade of HTL/KAI2 that has diverged from the KAI2 clade of non-parasitic plants. The S. hermonthica SL receptors are included in this specific clade, which is called KAI2 divergent (KAI2d). Orobanche minor is an obligate root holoparasitic plant that grows completely dependent on the host for water and nutrients because of a lack of photosynthetic ability. Previous phylogenetic analysis of KAI2 proteins in O. minor has demonstrated the presence of at least five KAI2d clade genes. Here, we report that KAI2d3 and KAI2d4 in O. minor have the ability to act as the SL receptors. They directly interact with SLs in vitro, and when expressed in Arabidopsis, they rescue thermo-inhibited germination in response to the synthetic SL analog GR24. In particular, KAI2d3 showed high sensitivity to GR24 when expressed in Arabidopsis, suggesting that this receptor enables highly sensitive SL recognition in O. minor. Furthermore, we provide evidence that these KAI2d receptors are involved in the perception of sesquiterpene lactones, non-strigolactone-type germination inducers.

Cell Biology↗