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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

The ARG1-LIKE2 gene of Arabidopsis functions in a gravity signal transduction pathway that is genetically distinct from the PGM pathway

The arl2 mutants of Arabidopsis display altered root and hypocotyl gravitropism, whereas their inflorescence stems are fully gravitropic. Interestingly, mutant roots respond like the wild type to phytohormones and an inhibitor of polar auxin transport. Also, their cap columella cells accumulate starch similarly to wild-type cells, and mutant hypocotyls display strong phototropic responses to lateral light stimulation. The ARL2 gene encodes a DnaJ-like protein similar to ARG1, another protein previously implicated in gravity signal transduction in Arabidopsis seedlings. ARL2 is expressed at low levels in all organs of seedlings and plants. arl2-1 arg1-2 double mutant roots display kinetics of gravitropism similar to those of single mutants. However, double mutants carrying both arl2-1 and pgm-1 (a mutation in the starch-biosynthetic gene PHOSPHOGLUCOMUTASE) at the homozygous state display a more pronounced root gravitropic defect than the single mutants. On the other hand, seedlings with a null mutation in ARL1, a paralog of ARG1 and ARL2, behave similarly to the wild type in gravitropism and other related assays. Taken together, the results suggest that ARG1 and ARL2 function in the same gravity signal transduction pathway in the hypocotyl and root of Arabidopsis seedlings, distinct from the pathway involving PGM.

NASA Discipline Plant Biology↗
NASA NTRS2000

Columella cells revisited: novel structures, novel properties, and a novel gravisensing model

A hundred years of research has not produced a clear understanding of the mechanism that transduces the energy associated with the sedimentation of starch-filled amyloplast statoliths in root cap columella cells into a growth response. Most models postulate that the statoliths interact with microfilaments (MF) to transmit signals to the plasma membrane (or ER), or that sedimentation onto these organelles produces the signals. However, no direct evidence for statolith-MF links has been reported, and no asymmetric structures of columella cells have been identified that might explain how a root turned by 90 degrees knows which side is up. To address these and other questions, we have (1) quantitatively examined the effects of microgravity on the size, number, and spatial distribution of statoliths; (2) re-evaluated the ultrastructure of columella cells in high-pressure frozen/freeze-substituted roots; and (3) followed the sedimentation dynamics of statolith movements in reoriented root tips. The findings have led to the formulation of a new model for the gravity-sensing apparatus of roots, which envisages the cytoplasm pervaded by an actin-based cytoskeletal network. This network is denser in the ER-devoid central region of the cell than in the ER-rich cell cortex and is coupled to receptors in the plasma membrane. Statolith sedimentation is postulated to disrupt the network and its links to receptors in some regions of the cell cortex, while allowing them to reform in other regions and thereby produce a directional signal.

NASA Discipline Cell Biology↗
NASA NTRS1989

A growth analysis of waterlogging damage in mung bean (Phaseolus aureus)

Mung beans (Phaseolus aureus Roxb.) were grown for 2 weeks in gravel-vermiculite soilless mix in a growth chamber and subjected to a 1-week waterlogging period followed by a 1-week recovery period. Sequential harvests were made to determine the time course of effects of waterlogging and subsequent recovery on growth parameters by techniques of growth analysis. Root dry matter was the first to be affected, along with an increase in leaf dry matter and specific leaf weight. After a 1-week waterlogging period, specific leaf weight had more than doubled in the stressed plants. Leaf area declined in relation to the control plants as did the ratio of root dry matter to shoot dry matter. During the recovery period there was an increase in the dry matter allocation to the roots relative to the shoot. Specific leaf weight fell to control levels although the rate of leaf area elaboration did not increase during this time, suggesting a redistribution of stored assimilates from the leaves. Net assimilation rate increased during the waterlogging period, probably due to a restriction in root metabolism and reduced translocation out of the leaf rather than to an increase in photosynthesis. Net assimilation rate of waterlogged plants was severely reduced compared with control plants during the recovery period. Both relative growth rate and leaf area duration declined during the waterlogging period and declined further subsequent to the waterlogging treatment. The results illustrate the interrelationships between root and shoot carbon budgets in mung bean during response to the stress of waterlogging.

Non-NASA Center↗
NASA NTRS2001

Growth in microgravity increases susceptibility of soybean to a fungal pathogen

The influence of microgravity on the susceptibility of soybean roots to Phytophthora sojae was studied during the Space Shuttle Mission STS-87. Seedlings of soybean cultivar Williams 82 grown in spaceflight or at unit gravity were untreated or inoculated with the soybean root rot pathogen P. sojae. At 3, 6 and 7 d after launch while still in microgravity, seedlings were photographed and then fixed for subsequent microscopic analysis. Post-landing analysis of the seedlings revealed that at harvest day 7 the length of untreated roots did not differ between flight and ground samples. However, the flight-grown roots infected with P. sojae showed more disease symptoms (percentage of brown and macerated areas) and the root tissues were more extensively colonized relative to the ground controls exposed to the fungus. Ethylene levels were higher in spaceflight when compared to ground samples. These data suggest that soybean seedlings grown in microgravity are more susceptible to colonization by a fungal pathogen relative to ground controls.

manned↗
NASA NTRS1987

Nodule activity and allocation of photosynthate of soybean during recovery from water stress

Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (psi w) of -2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule psi w also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule psi w of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N2-fixation activity.

Non-NASA Center↗
NASA NTRS1994

Ammonium and nitrate uptake by soybean during recovery from nitrogen deprivation

Soybean [Glycine max (L.) Merrill] plants that had been subjected to 15 d of nitrogen deprivation were resupplied for 10 d with 1.0 mol m-3 nitrogen provided as NO3-, NH4+, or NH4(+) + NO3- in flowing hydroponic culture. Plants in a fourth hydroponic system received 1.0 mol m-3 NO3- during both stress and resupply periods. Concentrations of soluble carbohydrates and organic acids in roots increased 210 and 370%, respectively, during stress. For the first day of resupply, however, specific uptake rates of nitrogen, determined by ion chromatography as depletion from solution, were lower for stressed than for non-stressed plants by 43% for NO3- resupply, by 32% for NH4(+) + NO3- resupply, and 86% for NH4+ resupply. When specific uptake of nitrogen for stressed plants recovered to rates for non-stressed plants at 6 to 8 d after nitrogen resupply, carbohydrates and organic acids in their roots had declined to concentrations lower than those of non-stressed plants. Recovery of nitrogen uptake capacity of roots thus does not appear to be regulated simply by the content of soluble carbon compounds within roots. Solution concentrations of NH4+ and NO3- were monitored at 62.5 min intervals during the first 3 d of resupply. Intermittent 'hourly' intervals of net influx and net efflux occurred. Rates of uptake during influx intervals were greater for the NH4(+)-resupplied than for the NO3(-)-resupplied plants. For NH4(+)-resupplied plants, however, the hourly intervals of efflux were more numerous than for NO3(-)-resupplied plants. It thus is possible that, instead of repressing NH4+ influx, increased accumulation of amino acids and NH4+ in NH4(+)-resupplied plants inhibited net uptake by stimulation of efflux on NH4+ absorbed in excess of availability of carbon skeletons for assimilation. Entry of NH4+ into root cytoplasm appeared to be less restricted than translocation of amino acids from the cytoplasm into the xylem.

NASA Discipline Number 61-10↗
NASA NTRS1998

The arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier

Auxins are plant hormones that mediate many aspects of plant growth and development. In higher plants, auxins are polarly transported from sites of synthesis in the shoot apex to their sites of action in the basal regions of shoots and in roots. Polar auxin transport is an important aspect of auxin functions and is mediated by cellular influx and efflux carriers. Little is known about the molecular identity of its regulatory component, the efflux carrier [Estelle, M. (1996) Current Biol. 6, 1589-1591]. Here we show that mutations in the Arabidopsis thaliana AGRAVITROPIC 1 (AGR1) gene involved in root gravitropism confer increased root-growth sensitivity to auxin and decreased sensitivity to ethylene and an auxin transport inhibitor, and cause retention of exogenously added auxin in root tip cells. We used positional cloning to show that AGR1 encodes a putative transmembrane protein whose amino acid sequence shares homologies with bacterial transporters. When expressed in Saccharomyces cerevisiae, AGR1 promotes an increased efflux of radiolabeled IAA from the cells and confers increased resistance to fluoro-IAA, a toxic IAA-derived compound. AGR1 transcripts were localized to the root distal elongation zone, a region undergoing a curvature response upon gravistimulation. We have identified several AGR1-related genes in Arabidopsis, suggesting a global role of this gene family in the control of auxin-regulated growth and developmental processes.

Non-NASA Center↗
NASA NTRS1996

A mutation in protein phosphatase 2A regulatory subunit A affects auxin transport in Arabidopsis

The phytohormone auxin controls processes such as cell elongation, root hair development and root branching. Tropisms, growth curvatures triggered by gravity, light and touch, are also auxin-mediated responses. Auxin is synthesized in the shoot apex and transported through the stem, but the molecular mechanism of auxin transport is not well understood. Naphthylphthalamic acid (NPA) and other inhibitors of auxin transport block tropic curvature responses and inhibit root and shoot elongation. We have isolated a novel Arabidopsis thaliana mutant designated roots curl in NPA (rcn1). Mutant seedlings exhibit altered responses to NPA in root curling and hypocotyl elongation. Auxin efflux in mutant seedlings displays increased sensitivity to NPA. The rcn1 mutation was transferred-DNA (T-DNA) tagged and sequences flanking the T-DNA insert were cloned. Analysis of the RCN1 cDNA reveals that the T-DNA insertion disrupts a gene for the regulatory A subunit of protein phosphatase 2A (PP2A-A). The RCN1 gene rescues the rcn1 mutant phenotype and also complements the temperature-sensitive phenotype of the Saccharomyces cerevisiae PP2A-A mutation, tpd3-1. These data implicate protein phosphatase 2A in the regulation of auxin transport in Arabidopsis.

Non-NASA Center↗
NASA NTRS2004

Control of gravitropic orientation. II. Dual receptor model for gravitropism

Gravitropism of vascular plants has been assumed to require a single gravity receptor mechanism. However, based on the evidence in Part I of this study, we propose that maize roots require two. The first mechanism is without a directional effect and, by itself, cannot give rise to tropism. Its role is quantitative facilitation of the second mechanism, which is directional like the gravitational force itself and provides the impetus for tropic curvature. How closely coupled the two mechanisms may be is, as yet, unclear. The evidence for dual receptors supports a general model for roots. When readiness for gravifacilitation, or gravifacilitation itself, is constitutive, orthogravitropic curvature can go to completion. If not constitutively enabled, gravifacilitation can be weak in the absence of light and water deficit or strong in the presence of light and water deficit. In either case, it can decay and permit roots to assume reproducible non-vertical orientations (plagiogravitropic or plagiotropic orientations) without using non-vertical setpoints. In this way roots are deployed in a large volume of soil. Gravitropic behaviours in shoots are more diverse than in roots, utilising oblique and horizontal as well as vertical setpoints. As a guide to future experiments, we assess how constitutive v. non-constitutive modes of gravifacilitation might contribute to behaviours based on each kind of setpoint.

NASA Discipline Plant Biology↗
NASA NTRS2009

Understanding the Scalability of Bayesian Network Inference using Clique Tree Growth Curves

Bayesian networks (BNs) are used to represent and efficiently compute with multi-variate probability distributions in a wide range of disciplines. One of the main approaches to perform computation in BNs is clique tree clustering and propagation. In this approach, BN computation consists of propagation in a clique tree compiled from a Bayesian network. There is a lack of understanding of how clique tree computation time, and BN computation time in more general, depends on variations in BN size and structure. On the one hand, complexity results tell us that many interesting BN queries are NP-hard or worse to answer, and it is not hard to find application BNs where the clique tree approach in practice cannot be used. On the other hand, it is well-known that tree-structured BNs can be used to answer probabilistic queries in polynomial time. In this article, we develop an approach to characterizing clique tree growth as a function of parameters that can be computed in polynomial time from BNs, specifically: (i) the ratio of the number of a BN's non-root nodes to the number of root nodes, or (ii) the expected number of moral edges in their moral graphs. Our approach is based on combining analytical and experimental results. Analytically, we partition the set of cliques in a clique tree into different sets, and introduce a growth curve for each set. For the special case of bipartite BNs, we consequently have two growth curves, a mixed clique growth curve and a root clique growth curve. In experiments, we systematically increase the degree of the root nodes in bipartite Bayesian networks, and find that root clique growth is well-approximated by Gompertz growth curves. It is believed that this research improves the understanding of the scaling behavior of clique tree clustering, provides a foundation for benchmarking and developing improved BN inference and machine learning algorithms, and presents an aid for analytical trade-off studies of clique tree clustering using growth curves.

Mengshoel, Ole Jakob↗
NASA NTRS2010

Understanding the Scalability of Bayesian Network Inference Using Clique Tree Growth Curves

One of the main approaches to performing computation in Bayesian networks (BNs) is clique tree clustering and propagation. The clique tree approach consists of propagation in a clique tree compiled from a Bayesian network, and while it was introduced in the 1980s, there is still a lack of understanding of how clique tree computation time depends on variations in BN size and structure. In this article, we improve this understanding by developing an approach to characterizing clique tree growth as a function of parameters that can be computed in polynomial time from BNs, specifically: (i) the ratio of the number of a BN s non-root nodes to the number of root nodes, and (ii) the expected number of moral edges in their moral graphs. Analytically, we partition the set of cliques in a clique tree into different sets, and introduce a growth curve for the total size of each set. For the special case of bipartite BNs, there are two sets and two growth curves, a mixed clique growth curve and a root clique growth curve. In experiments, where random bipartite BNs generated using the BPART algorithm are studied, we systematically increase the out-degree of the root nodes in bipartite Bayesian networks, by increasing the number of leaf nodes. Surprisingly, root clique growth is well-approximated by Gompertz growth curves, an S-shaped family of curves that has previously been used to describe growth processes in biology, medicine, and neuroscience. We believe that this research improves the understanding of the scaling behavior of clique tree clustering for a certain class of Bayesian networks; presents an aid for trade-off studies of clique tree clustering using growth curves; and ultimately provides a foundation for benchmarking and developing improved BN inference and machine learning algorithms.

Mengshoel, Ole J.↗
NASA NTRS2016

Soil Moisture Active Passive Mission L4_SM Data Product Assessment (Version 2 Validated Release)

During the post-launch SMAP calibration and validation (Cal/Val) phase there are two objectives for each science data product team: 1) calibrate, verify, and improve the performance of the science algorithm, and 2) validate the accuracy of the science data product as specified in the science requirements and according to the Cal/Val schedule. This report provides an assessment of the SMAP Level 4 Surface and Root Zone Soil Moisture Passive (L4_SM) product specifically for the product's public Version 2 validated release scheduled for 29 April 2016. The assessment of the Version 2 L4_SM data product includes comparisons of SMAP L4_SM soil moisture estimates with in situ soil moisture observations from core validation sites and sparse networks. The assessment further includes a global evaluation of the internal diagnostics from the ensemble-based data assimilation system that is used to generate the L4_SM product. This evaluation focuses on the statistics of the observation-minus-forecast (O-F) residuals and the analysis increments. Together, the core validation site comparisons and the statistics of the assimilation diagnostics are considered primary validation methodologies for the L4_SM product. Comparisons against in situ measurements from regional-scale sparse networks are considered a secondary validation methodology because such in situ measurements are subject to up-scaling errors from the point-scale to the grid cell scale of the data product. Based on the limited set of core validation sites, the wide geographic range of the sparse network sites, and the global assessment of the assimilation diagnostics, the assessment presented here meets the criteria established by the Committee on Earth Observing Satellites for Stage 2 validation and supports the validated release of the data. An analysis of the time average surface and root zone soil moisture shows that the global pattern of arid and humid regions are captured by the L4_SM estimates. Results from the core validation site comparisons indicate that "Version 2" of the L4_SM data product meets the self-imposed L4_SM accuracy requirement, which is formulated in terms of the ubRMSE: the RMSE (Root Mean Square Error) after removal of the long-term mean difference. The overall ubRMSE of the 3-hourly L4_SM surface soil moisture at the 9 km scale is 0.035 cubic meters per cubic meter requirement. The corresponding ubRMSE for L4_SM root zone soil moisture is 0.024 cubic meters per cubic meter requirement. Both of these metrics are comfortably below the 0.04 cubic meters per cubic meter requirement. The L4_SM estimates are an improvement over estimates from a model-only SMAP Nature Run version 4 (NRv4), which demonstrates the beneficial impact of the SMAP brightness temperature data. L4_SM surface soil moisture estimates are consistently more skillful than NRv4 estimates, although not by a statistically significant margin. The lack of statistical significance is not surprising given the limited data record available to date. Root zone soil moisture estimates from L4_SM and NRv4 have similar skill. Results from comparisons of the L4_SM product to in situ measurements from nearly 400 sparse network sites corroborate the core validation site results. The instantaneous soil moisture and soil temperature analysis increments are within a reasonable range and result in spatially smooth soil moisture analyses. The O-F residuals exhibit only small biases on the order of 1-3 degrees Kelvin between the (re-scaled) SMAP brightness temperature observations and the L4_SM model forecast, which indicates that the assimilation system is largely unbiased. The spatially averaged time series standard deviation of the O-F residuals is 5.9 degrees Kelvin, which reduces to 4.0 degrees Kelvin for the observation-minus-analysis (O-A) residuals, reflecting the impact of the SMAP observations on the L4_SM system. Averaged globally, the time series standard deviation of the normalized O-F residuals is close to unity, which would suggest that the magnitude of the modeled errors approximately reflects that of the actual errors. The assessment report also notes several limitations of the "Version 2" L4_SM data product and science algorithm calibration that will be addressed in future releases. Regionally, the time series standard deviation of the normalized O-F residuals deviates considerably from unity, which indicates that the L4_SM assimilation algorithm either over- or under-estimates the actual errors that are present in the system. Planned improvements include revised land model parameters, revised error parameters for the land model and the assimilated SMAP observations, and revised surface meteorological forcing data for the operational period and underlying climatological data. Moreover, a refined analysis of the impact of SMAP observations will be facilitated by the construction of additional variants of the model-only reference data. Nevertheless, the “Version 2” validated release of the L4_SM product is sufficiently mature and of adequate quality for distribution to and use by the larger science and application communities.

SMAP L4_SM↗
NASA NTRS2016

Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 +/- 0.1 fm s(exp -2)/square root of Hz, or (0.54 +/- 0.01) x 10(exp -15) g/square root of Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 +/- 0.3) fm square root of Hz, about 2 orders of magnitude better than requirements. At f less than or equal to 0.5 mHz we observe a low-frequency tail that stays below 12 fm s(exp -2)/square root of Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.

space science↗
NASA NTRS2018

Soil Moisture Active Passive (SMAP) Project Assessment Report for Version 4 of the L4_SM Data Product

This report provides an assessment of Version 4 of the SMAP Level 4 Surface and Root Zone Soil Moisture (L4_SM) product, released on 14 June 2018. The assessment includes comparisons of L4_SM soil moisture and temperature estimates with in situ measurements from core validation sites and sparse networks. The assessment further includes a global evaluation of the internal diagnostics from the ensemble-based data assimilation system that is used to generate the L4_SM product, including observation-minus-forecast (O-F) brightness temperature residuals and soil moisture analysis increments.Together, the core validation site comparisons and the statistics of the assimilation diagnostics areconsidered primary validation methodologies for the L4_SM product. Comparisons against in situ measurements from regional-scale sparse networks are considered a secondary validation methodology because such in situ measurements are subject to upscaling errors from the point-scale to the grid-cell scale of the data product.The Version 4 L4_SM product benefits from an improved land surface modeling system and from retrospective surface meteorological forcing data that are as consistent as possible with the present-day datain terms of their climatology. Specifically, the model changes include revised parameters and parameterizations for (i) the surface energy balance, (ii) recharge from below of the model's surface excess reservoir, and (iii) the snow depletion curve. Updated ancillary inputs include improved datasets for landcover, topography, and vegetation height. The Version 4 algorithm further includes a revised approach to precipitation corrections that improves the precipitation climatology in Africa and the high-latitudes. Moreover, for system calibration the model is forced retrospectively with MERRA-2 reanalysis data, which are more consistent with the near-real time GEOS forward processing (FP) data used during the SMAP period than the retrospective GEOS data that were available for previous L4_SM versions. An analysis of the time-average surface and root zone soil moisture shows that the global pattern ofarid and humid regions is captured by the Version 4 L4_SM estimates. Owing to the changes in the landsurface modeling system, surface soil moisture is typically drier by several volumetric percent in Version 4 compared to Version 3, whereas root zone soil moisture is wetter in Version 4 in some regions and drierin others. Because of these climatological differences, the Version 3 and Version 4 products should not be combined into a single dataset for use in applications.Results from the core validation site comparisons indicate that Version 4 of the L4_SM data product meets the self-imposed L4_SM accuracy requirement, which is formulated in terms of the RMSE after removal of the long-term mean difference (ubRMSE). The overall ubRMSE of the 3-hourly L4_SM dataat the 9 km scale is 0.039 m3 m-3 for surface soil moisture and 0.029 m3 m-3 for root zone soil moisture,below the 0.04 m3 m-3 requirement. The L4_SM estimates are an improvement over estimates from a model-only Nature Run version 7.2 (NRv7.2), which demonstrates the beneficial impact of the SMAP brightness temperature data. Overall, L4_SM surface and root zone soil moisture estimates are more skillful than NRv7.2 estimates, with statistically significant improvements at the 5% level for surface soil moisture R and anomaly R values. Results from comparisons of the L4_SM product to i

Reichle, Rolf H.↗
NASA NTRS2023

3D Printed Substrate

In preparation for long-term, manned, deep space missions, NASA requires a sustainable system for crop and food production. This system has a variety of benefits, including a fresh food supply, improvements in air quality, a lower need to resupply and psychological benefits for the gardeners. Specifically, NASA is attempting to improve and iterate their Vegetable Production System (VEGGIE), a plant growth unit currently aboard the International Space Station (ISS). The VEGGIE unit is highly dependent on a variety of factors, including passive water delivery, growth lights, rooting pillows and cabin conditions. While previous teams have improved and redesigned water reservoirs, the primary objective of the project was to create a new substrate unit to replace the current rooting pillow design. The current design consists of an electrostatic bag filled with arcillite and a slow-release fertilizer pellet. The prototype design retains the fertilizer pellet for nutrient consistency, however the outer bag and arcillite fillings have been replaced with a 3D printed lattice block. This lattice block has several key points that allow it to function in similar ways to the current design: 1. The lattice planes are porous, with each pore offset such that the overall porosity is the same as the arcillite filling. 2. The block demonstrates a wicking nature and is able to pull water upwards towards the roots. This minimizes time needed to integrate with the existing water reservoir. 3. The filament used is highly flexible and is able to pull apart to accommodate root growth. 4. The lattice planes are connected by microfibers left behind from the printing process. These fibers provide support for the growing roots and keep the lattice planes properly aligned. The substrate block design seeks to reduce the payload costs by being entirely 3D printed. While filament would still need to be provided to the ISS, it is far less expensive than shipping arcillite due to the significantly lower weight. The final design has iterated the lattice plane concept and utilizes vertically placed planes with pores running parallel to the water reservoir. This design has reliably shown water uptake and retention and has been successful in growing multiple romaine lettuce plants. Future work should include further growth testing using multiple plant species, compost and reusability testing, food safety testing and microgravity growth testing.

Affan Bhutta↗
DOE OSTI2022

Simple through-plane spatial filter for 2D MRI projections

A simple spatial filter for 2D projection MR imaging is introduced. It works in the third (unresolved) direction to eliminate uniform or slowly varying interfering background signals. A constant amplitude gradient pulse in the unresolved direction is applied at the same time as the usual phase encode gradient during 2D acquisition. The filter is demonstrated for root imaging in soil, where background soil water signals can be troublesome. The filter suppresses the soil water signal while preserving the desired signal of plant roots. Fundamental to the operation of the filter is that the roots are sparse in the image domain, meaning there are relatively few pixels with multiple roots present. Here, the performance of the through-plane filter is demonstrated and compares favorably to more conventional in-plane spatial filtering.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Identification of a diguanylate cyclase expressed in the presence of plants and its application for discovering candidate gene products involved in plant colonization by Pantoea sp. YR343

Microbial colonization of plant roots is a highly complex process that requires the coordination and regulation of many gene networks, yet the identities and functions of many of these gene products have yet to be discovered. Pantoea sp. YR343, a gamma-proteobacterium isolated from the rhizosphere of Populus deltoides , forms robust biofilms along the root surfaces of Populus and possesses plant growth-promoting characteristics. In this work, we identified three diguanylate cyclases in the plant-associated microbe Pantoea sp. YR343 that are expressed in the presence of plant roots. One of these diguanylate cyclases, DGC2884, localizes to discrete sites in the cells and its overexpression results in reduced motility and increased EPS production and biofilm formation. We performed a genetic screen by expressing this diguanylate cyclase from an inducible promoter in order to identify candidate gene products that may be involved in root colonization by Pantoea sp. YR343. Further, we demonstrate the importance of other domains in DGC2884 to its activity, which in combination with the genes identified by transposon mutagenesis, may yield insights into the mechanisms of plant association as well as the activity and regulation of homologous enzymes in medically and agriculturally relevant microbes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Data from: "Warming of alpine tundra enhances belowground production and shifts community towards resource acquisition traits"

This archive contains data used to draw conclusions in “Warming of alpine tundra enhances belowground production and shifts community towards resource acquisition traits”, by Yang et al. 2020. Data were collected on Niwot Ridge, in an alpine meadow within the Alpine Treeline Warming Experiment (ATWE) field sites in Colorado, USA. Samples were also processed in the U.S. Geological Survey Forest and Rangeland Ecosystem Science Center, in Boise, Idaho. File formats in this archive include comma-separated values (.csv), portable document format (.pdf), Microsoft Excel (.xlsx), and two types of geospatial files: keyhole markup language (.kml), and ESRI shapefiles (.shp). Leaf scans are .jpg images, and root scans are .tiff/.tif images.The .csv files can be opened using R, Microsoft Excel, or any simple text-editing software such as TextEdit and Notepad. Microsoft Excel files can be opened using Microsoft Excel, and .pdf files can be opened with Adobe Acrobat Reader, Preview, or other compatible programs. Scanned images can be opened using any photo and/or picture viewing software.The .kml file can be opened using Google Earth and Google Maps, and the shapefiles can be opened by any programs compatible with shapefiles, such as the ArcGIS Desktop suite, and QGIS.------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Measures of belowground net primary productivity (BNPP) are required to understand whether aboveground net primary production (ANPP) changes reflect changes in allocation or are indicative of a whole plant NPP response. Plant functional traits provide a key way to scale from the individual plant to the community level, and provide insight into drivers of NPP responses to environmental change. We used infrared heaters to warm an alpine plant community at Niwot Ridge, Colorado, and applied supplemental water to compensate for soil water loss induced by warming. We measured ANPP, BNPP, and leaf and root functional traits across treatments after 5 years of continuous warming. Community-level ANPP and total NPP (ANPP + BNPP) did not respond to heating or watering, but BNPP increased in response to heating. Heating decreased community-level leaf dry matter content and increased total root length, indicating a shift in strategy from resource conservation to acquisition in response to warming.

13C/12C isotope ratio↗