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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Hormonal induction and antihormonal inhibition of tracheary element differentiation in Zinnia cell cultures

Mechanically isolated mesophyll cells of Zinnia elegans L. cv Envy differentiate to tracheary elements when cultured in inductive medium containing sufficient auxin and cytokinin. Tracheary element differentiation was induced by the three auxins (alpha-naphthaleneacetic acid, indole-3-acetic acid, and 2,4-dichlorophenoxyacetic acid) and four cytokinins (6-benzyladenine, kinetin, 2-isopentenyladenine and zeatin) tested. Tracheary element formation is inhibited or delayed if the inductive medium is supplemented with an anticytokinin, antiauxin, or inhibitor of auxin transport.

NASA Program Space Biology↗
DOE OSTI2026

Novel Cell-Type-Specific Drought-Responsive Proteins in Root Tips of Field-Grown Perennial Switchgrass

The root-tip region of plants, including the root cap, forms the most basal terminal of the root and exhibits a high degree of cellular complexity in terms of morphology, cytological function, and interaction with environmental cues in the soil. Cells in this region follow a developmental trajectory, transitioning from stem cells to meristematic cells, and ultimately to fully differentiated cell types. However, our understanding of root-tip cell-type specific proteomic responses to abiotic stresses, such as drought, particularly under field conditions, remains limited. This study aimed to identify spatially resolved, cell type-specific proteomes in switchgrass (Panicum virgatum) root tips under drought stress. Root tips were collected from seven-year-old, field-grown switchgrass ‘Alamo’ plants excavated under both well-watered and long-term drought conditions. Cell type-specific proteins were identified using laser capture microdissection (LCM) coupled with nanoPOTS (Nanodroplet Processing in One Pot for Trace Samples) and nano-LC-MS proteomics analysis. Five distinct cell types were targeted: (1) cells in the quiescent center and stem cell niche (QuC), (2) protodermal epidermal cells (PEC) in the meristematic zone, (3) epidermal cells in the transition and elongation zones above the root cap (Epi), (4) peripheral root cap cells (PRC), forming 2–3 layers below the PEC and 1–2 layers above the root border cells, and (5) columella root cap cells (Col) comprising of the columella initials and a single underlying layer of cells undergoing active growth. Principal component analysis (PCA) revealed clear separation among the five targeted cell types, confirming distinct proteomic profiles. Proteins predominantly enriched in each cell type were linked to distinct cellular functions, with QuC cells showing involvement in chromosomal behavior, DNA replication, and mitosis—key processes for stem cell niche regulation. Drought stress resulted in alterations of proteostasis, as evidenced by significant decreases in ribosomal proteins and increases in protein synthesis inhibitors. Moreover, drought stress induced unique cell-type–specific proteins involved in phytohormone biosynthesis and signaling pathways, including auxin, cytokinin, and jasmonic acid. In particular, QuC cells were more highly enriched in proteins associated with DNA repair and mitotic processes. Metabolic pathways related to amino acids, carbohydrates, and lipids were differentially affected in a cell-type–dependent manner, whereas general stress-responsive proteins exhibited consistent changes across all five cell types. Overall, this study provides unique spatially resolved, cell-type-specific proteomic profiles in root tips, representing a significant advancement in our understanding of the cellular mechanisms underlying plant responses to drought stress in natural field conditions.

perennial grass↗
DOE OSTI2023

Molecular and biochemical characterization of rice developed through conventional integration of nDart1-0 transposon gene

Mutations, the genetic variations in genomic sequences, play an important role in molecular biology and biotechnology. During DNA replication or meiosis, one of the mutations is transposons or jumping genes. An indigenous transposon nDart1-0 was successfully introduced into local indica cultivar Basmati-370 from transposon-tagged line viz., GR-7895 (japonica genotype) through conventional breeding technique, successive backcrossing. Plants from segregating populationsshowed variegated phenotypes were tagged as BM-37 mutants. Blast analysis of the sequence data revealed that the GTP-binding protein, located on the BAC clone OJ1781_H11 of chromosome 5, contained an insertion of DNA transposon nDart1-0. The nDart1-0 has “A” at position 254 bp, whereas nDart1 homologs have “G”, which efficiently distinguishes nDart1-0 from its homologs. The histological analysis revealed that the chloroplast of mesophyll cells in BM-37 was disrupted with reduction in size of starch granules and higher number of osmophillic plastoglobuli, which resulted in decreased chlorophyll contents and carotenoids, gas exchange parameters (Pn, g, E, Ci), and reduced expression level of genes associated with chlorophyll biosynthesis, photosynthesis and chloroplast development. Along with the rise of GTP protein, the salicylic acid (SA) and gibberellic acid (GA) and antioxidant contents(SOD) and MDA levels significantly enhanced, while, the cytokinins (CK), ascorbate peroxidase (APX), catalase (CAT), total flavanoid contents (TFC) and total phenolic contents (TPC) significantly reduced in BM-37 mutant plants as compared with WT plants. These results support the notion that GTP-binding proteins influence the process underlying chloroplast formation. Therefore, it is anticipated that to combat biotic or abiotic stress conditions, the nDart1-0 tagged mutant (BM-37) of Basmati-370 would be beneficial.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Heritable gene editing in tomato through viral delivery of isopentenyl transferase and single-guide RNAs to latent axillary meristematic cells

Realizing the full potential of genome editing for crop improvement has been slow due to inefficient methods for reagent delivery and the reliance on tissue culture for creating gene-edited plants. RNA viral vectors offer an alternative approach for delivering gene engineering reagents and bypassing the tissue culture requirement. Viruses, however, are often excluded from the shoot apical meristem, making virus-mediated gene editing inefficient in some species. Here, we developed effective approaches for generating gene-edited shoots in Cas9-expressing transgenic tomato plants using RNA virus-mediated delivery of single-guide RNAs (sgRNAs). RNA viral vectors expressing sgRNAs were either delivered to leaves or sites near axillary meristems. Trimming of the apical and axillary meristems induced new shoots to form from edited somatic cells. To further encourage the induction of shoots, we used RNA viral vectors to deliver sgRNAs along with the cytokinin biosynthesis gene, isopentenyl transferase. Abundant, phenotypically normal, gene-edited shoots were induced per infected plant with single and multiplexed gene edits fixed in the germline. The use of viruses to deliver both gene editing reagents and developmental regulators overcomes the bottleneck in applying virus-induced gene editing to dicotyledonous crops such as tomato and reduces the dependency on tissue culture.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

GWAS supported by computer vision identifies large numbers of candidate regulators of in planta regeneration in Populus trichocarpa

Plant regeneration is an important dimension of plant propagation and a key step in the production of transgenic plants. However, regeneration capacity varies widely among genotypes and species, the molecular basis of which is largely unknown. Association mapping methods such as genome-wide association studies (GWAS) have long demonstrated abilities to help uncover the genetic basis of trait variation in plants; however, the performance of these methods depends on the accuracy and scale of phenotyping. To enable a large-scale GWAS of in planta callus and shoot regeneration in the model tree Populus, we developed a phenomics workflow involving semantic segmentation to quantify regenerating plant tissues over time. We found that the resulting statistics were of highly non-normal distributions, and thus employed transformations or permutations to avoid violating assumptions of linear models used in GWAS. We report over 200 statistically supported quantitative trait loci (QTLs), with genes encompassing or near to top QTLs including regulators of cell adhesion, stress signaling, and hormone signaling pathways, as well as other diverse functions. Our results encourage models of hormonal signaling during plant regeneration to consider keystone roles of stress-related signaling (e.g. involving jasmonates and salicylic acid), in addition to the auxin and cytokinin pathways commonly considered. The putative regulatory genes and biological processes we identified provide new insights into the biological complexity of plant regeneration, and may serve as new reagents for improving regeneration and transformation of recalcitrant genotypes and species.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Agave REVEILLE1 regulates the onset and release of seasonal dormancy in Populus

Abstract Deciduous woody plants like poplar (Populus spp.) have seasonal bud dormancy. It has been challenging to simultaneously delay the onset of bud dormancy in the fall and advance bud break in the spring, as bud dormancy, and bud break were thought to be controlled by different genetic factors. Here, we demonstrate that heterologous expression of the REVEILLE1 gene (named AaRVE1) from Agave (Agave americana) not only delays the onset of bud dormancy but also accelerates bud break in poplar in field trials. AaRVE1 heterologous expression increases poplar biomass yield by 166% in the greenhouse. Furthermore, we reveal that heterologous expression of AaRVE1 increases cytokinin contents, represses multiple dormancy-related genes, and up-regulates bud break-related genes, and that AaRVE1 functions as a transcriptional repressor and regulates the activity of the DORMANCY-ASSOCIATED PROTEIN 1 (DRM1) promoter. Our findings demonstrate that AaRVE1 appears to function as a regulator of bud dormancy and bud break, which has important implications for extending the growing season of deciduous trees in frost-free temperate and subtropical regions to increase crop yield.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Transcriptome and DNA methylome divergence of inflorescence development between 2 ecotypes in Panicum hallii

The morphological diversity of the inflorescence determines flower and seed production, which is critical for plant adaptation. Hall's panicgrass (Panicum hallii, P. hallii) is a wild perennial grass that has been developed as a model to study perennial grass biology and adaptive evolution. Highly divergent inflorescences have evolved between the 2 major ecotypes in P. hallii, the upland ecotype (P. hallii var hallii, HAL2 genotype) with compact inflorescence and large seed and the lowland ecotype (P. hallii var filipes, FIL2 genotype) with an open inflorescence and small seed. Here we conducted a comparative analysis of the transcriptome and DNA methylome, an epigenetic mark that influences gene expression regulation, across different stages of inflorescence development using genomic references for each ecotype. Global transcriptome analysis of differentially expressed genes (DEGs) and co-expression modules underlying the inflorescence divergence revealed the potential role of cytokinin signaling in heterochronic changes. Comparing DNA methylome profiles revealed a remarkable level of differential DNA methylation associated with the evolution of P. hallii inflorescence. We found that a large proportion of differentially methylated regions (DMRs) were located in the flanking regulatory regions of genes. Intriguingly, we observed a substantial bias of CHH hypermethylation in the promoters of FIL2 genes. The integration of DEGs, DMRs, and $K_a$/$K_s$ ratio results characterized the evolutionary features of DMR-associated DEGs that contribute to the divergence of the P. hallii inflorescence. This study provides insights into the transcriptome and epigenetic landscape of inflorescence divergence in P. hallii and a genomic resource for perennial grass biology.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Functional and comparative genomics reveals conserved noncoding sequences in the nitrogen–fixing clade

Nitrogen is one of the most inaccessible plant nutrients, but certain species have overcome this limitation by establishing symbiotic interactions with nitrogen-fixing bacteria in the root nodule. This root–nodule symbiosis (RNS) is restricted to species within a single clade of angiosperms, suggesting a critical, but undetermined, evolutionary event at the base of this clade. To identify putative regulatory sequences implicated in the evolution of RNS, we evaluated the genomes of 25 species capable of nodulation and identified 3091 conserved noncoding sequences (CNS) in the nitrogen-fixing clade (NFC). We show that the chromatin accessibility of 452 CNS correlates significantly with the regulation of genes responding to lipochitooligosaccharides in Medicago truncatula. These included 38 CNS in proximity to 19 known genes involved in RNS. Five such regions are upstream of MtCRE1, Cytokinin Response Element 1, required to activate a suite of downstream transcription factors necessary for nodulation in M. truncatula. Genetic complementation of an Mtcre1 mutant showed a significant decrease of nodulation in the absence of the five CNS, when they are driving the expression of a functional copy of MtCRE1. CNS identified in the NFC may harbor elements required for the regulation of genes controlling RNS in M. truncatula.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Bioenergy sorghum stem growth regulation: intercalary meristem localization, development, and gene regulatory network analysis

SUMMARY Bioenergy sorghum is a highly productive drought tolerant C 4 grass that accumulates 80% of its harvestable biomass in approximately 4 m length stems. Stem internode growth is regulated by development, shading, and hormones that modulate cell proliferation in intercalary meristems (IMs). In this study, sorghum stem IMs were localized above the pulvinus at the base of elongating internodes using magnetic resonance imaging, microscopy, and transcriptome analysis. A change in cell morphology/organization occurred at the junction between the pulvinus and internode where LATERAL ORGAN BOUNDARIES ( SbLOB ), a boundary layer gene, was expressed. Inactivation of an AGCVIII kinase in DDYM ( dw2 ) resulted in decreased SbLOB expression, disrupted IM localization, and reduced internode cell proliferation. Transcriptome analysis identified approximately 1000 genes involved in cell proliferation, hormone signaling, and other functions selectively upregulated in the IM compared with a non‐meristematic stem tissue. This cohort of genes is expressed in apical dome stem tissues before localization of the IM at the base of elongating internodes. Gene regulatory network analysis identified connections between genes involved in hormone signaling and cell proliferation. The results indicate that gibberellic acid induces accumulation of growth regulatory factors (GRFs) known to interact with ANGUSTIFOLIA (SbAN3), a master regulator of cell proliferation. GRF:AN3 was predicted to induce SbARF3/ETT expression and regulate SbAN3 expression in an auxin‐dependent manner. GRFs and ARFs regulate genes involved in cytokinin and brassinosteroid signaling and cell proliferation. The results provide a molecular framework for understanding how hormone signaling regulates the expression of genes involved in cell proliferation in the stem IM.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Phloem Exudate Protein Profiles during Drought and Recovery Reveal Abiotic Stress Responses in Tomato Vasculature

Drought is the leading cause of agricultural yield loss among all abiotic stresses, and the link between water deficit and phloem protein contents is relatively unexplored. Here we collected phloem exudates from Solanum lycopersicum leaves during periods of drought stress and recovery. Our analysis identified 2558 proteins, the most abundant of which were previously localized to the phloem. Independent of drought, enrichment analysis of the total phloem exudate protein profiles from all samples suggests that the protein content of phloem sap is complex, and includes proteins that function in chaperone systems, branched-chain amino acid synthesis, trehalose metabolism, and RNA silencing. We observed 169 proteins whose abundance changed significantly within the phloem sap, either during drought or recovery. Proteins that became significantly more abundant during drought include members of lipid metabolism, chaperone-mediated protein folding, carboxylic acid metabolism, abscisic acid signaling, cytokinin biosynthesis, and amino acid metabolism. Conversely, proteins involved in lipid signaling, sphingolipid metabolism, cell wall organization, carbohydrate metabolism, and a mitogen-activated protein kinase are decreased during drought. Our experiment has achieved an in-depth profiling of phloem sap protein contents during drought stress and recovery that supports previous findings and provides new evidence that multiple biological processes are involved in drought adaptation.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1972

Plant Adaptation to Cold. 1: Chlorophyll. 2: Minerals

A number of montane herbs in northern Utah typically form flower buds beneath the snow cover and flower either through it or immediately after its recession. Two of these species, one naturally occurring, Claytonia lanceolata, and one cultivated bulb, Galanthus nivalis, were investigated for their response to this stress environment. Snow depth patterns, chlorophyll content of tissues, and plants grown in light-tight boxes, suggest that light passing through the snow to reach plants growing underneath is not critically involved in the timing of their developmental cycles or in their ability to endure this low temperature environment. Ability to endure stress seems to be closely related in a number of ways to activity at the plant membranes. Plants were protected from low temperature damage by application of cytokinin or calcium, both of which probably acted at the membrane. Potassium calcium antagonisms were reflected in the internal distribution of the ions under natural stress conditions; and plants that differentiated at the meristem while growing through the snow accumulated calcium at the tip during this growth.

Rosen, P.↗
NASA NTRS1981

Development of guayule (Parthenium argentatum) research in cell culture

Utilizing the lateral buds of known high rubber producing plants as explants in culture medium specifically designed to engender shoot development and to prevent callus formation, unlimited numbers of replicate plants can be produced. Each has the same genotype as the parent. This procedure has long been used to rid plants of virus, the latter generally does not occur in the embryonic tissues of the bud; it also, by virtue of its axenic nature, eliminates all microorganisms characteristic of the parent plant. Auxins were found essential to callus formation, but since the latter is known to bring about chromosomal aberrations, it was avoided. The cytokinin benzylaminopurine strongly stimulated shoot growth, and the number of regenerated buds on the inoculum was proportional to its concentration. These buds produced shoots several centimeters in length which were caused to root on medium containing indolebutyric acid. Transferred to the septic condition of soil, the plantlets were gradually brought into full sunlight where they showed a brief vegetative growth with production of mature leaves, and flowered.

Ball, E. A.↗
NASA NTRS1983

Tissue-Culture Method of Cloning Rubber Plants

Guayule plant, a high-yield rubber plant cloned by tissue-culture method to produce multiple new plants that mature quickly. By adjusting culture medium, excised shoot tip produces up to 50 identical guayule plants. Varying concentration of cytokinin, single excised tip produces either 1 or several (up to 50) new plants.

Ball, E. A.↗
NASA NTRS1981

Development of guayule (parthenium argentatum)

The cytokinin benzylaminopurine strongly stimulated shoot growth, and the number of regenerated buds on the inoculum was proportional to its concentration. These buds produced shoots several centimeters in length which were caused to root on medium containing indolebutyric acid. Transferred to the septic condition of soil, the plantlets were gradually brought into full sunlight where they showed a brief vegetative growth with production of mature type leaves, and flowered. In contrast, seedlings of the same age remained vegetative. Chromosome studies of root smears from the tissue cultured plantlets showed that 2n = 36, the normal number for sexually reproducing guayules.

Ball, E. A.↗
NASA NTRS1985

Changes in spectral properties of detached birch leaves

A study conducted in order to determine the rate of changes in spectral properties of detached leaves and to evaluate the effectiveness of low temperature and cytokinins for delaying the changes, is examined. For five minutes, leaves from red birch are immersed in water or 0.001 M BAP, and then stored in plastic bags in the dark at either 5 or 25 C. Using a spectroradiometer and an integrating sphere, total directional-hemispherical reflectance and transmittance of the adaxial surface of the leaves are measured over the 400-1100 nm wavelength region. The results indicate that for leaves stored at 5 C for one week, the changes in the spectral properties are less than 5 percent of the initial values, whereas storage at 25 C promotes rapid senescence and large changes in the spectral properties. It is shown that low temperature is more effective than BAP in delaying senescence.

Daughtry, C. S. T.↗
NASA NTRS1989

In vitro regeneration of Basella alba L

Basella alba L. is a tropical vine used as a vegetable in some Asian and African countries. It has potential as a nontraditional crop for small family farms. A short day plant, it blooms during the fall, provided the temperatures are mild. In the southeastern U.S., the short days of fall are associated with subfreezing temperatures, and plants are killed before blooming. Attempts were made to regenerate the plant using tissue culture techniques. Several trials were conducted with different media, hormones, and explants. It was found that nodal segments on Gamborg medium regenerated shoots. Interaction studies of auxins and cytokinins indicated that its endogeneous auxin content might be high because callus proliferated in almost all treatments and roots initiated even when the medium was not supplemented with an auxin.

Edney, Norris Allen↗
NASA NTRS1998

Cultivation of Tomato Tissues Capable of Forming Flowers and Fruits in Vitro

The final phase of this research project was designed to develop a practical method for producing a steady supply of fresh cherry tomato fruits over a period of several months, for possible use as a fresh vegetable supplement to a standard diet of astronauts on extended missions. This effort was successful. We were able to excise immature flowers from Pixie tomato plants grown in a controlled condition room, implant them on artificial media under aseptic conditions, and get them to develop into edible fruits in a little over a month. The medium (Murashige-Skoog) was purchased from Sigma, supplemented with sugar plus a synthetic analog of the plant hormone cytokinin, and adjusted to pH 5.8. A temperature of at least 25 C and visible light helped to produce ripe red fruits within 7 weeks. To ensure a steady supply of such tomatoes, we found it possible to store the explanted flower buds in MS medium at 5 C for at least 6 weeks without significant loss of ability to develop into fruits. This means that many containers could be prepared before launch and put into a refrigerator; a convenient number could then be removed periodically to guarantee a succession of harvests during the life of an extended mission. Details are found in the attached reprints. Subsequent applications for funds for flight or continued research were denied, and the project was terminated.

Galston, Arthur W.↗
NASA NTRS1998

Factors enhancing Agrobacterium tumefaciens-mediated gene transfer in peanut (Arachis hypogaea L.)

Parameters enhancing Agrobacterium-mediated transfer of foreign genes to peanut (Arachis hypogaea L.) cells were investigated. An intron-containing beta-glucuronidase uidA (gusA) gene under the transcriptional control of CaMV 35S promoter served as a reporter. Transformation frequency was evaluated by scoring the number of sectors expressing GUS activity on leaf and epicotyl explants. The 'Valencia Select' market type cv. New Mexico was more amenable to Agrobacterium transformation than the 'runner' market type cultivars tested (Florunner, Georgia Runner, Sunrunner, or South Runner). The disarmed Agrobacterium tumefaciens strain EHA101 was superior in facilitating the transfer of uidA gene to peanut cells compared to the disarmed strain C58. Rinsing of explants in half-strength Murashige-Skoog (MS) media prior to infection by Agrobacterium significantly increased the transformation efficiency. The use of cocultivation media containing high auxin [1.0 or 2.5 mg/l (4.53 micromolar or 11.31 micromolar) 2,4-D] and low cytokinin [0.25 or 0.5 mg/l (1.0 micromolar or 2.0 micromolar) BA] promoted higher transformation than either hormone-free or thidiazuron-containing medium. The polarity of the epicotyl during cocultivation was important; explants incubated in an inverted (vertically) manner followed by a vertically upright position resulted in improved transformation and shoot regeneration frequencies. Preculture of explants in MS basal medium or with 2.5 mg thidiazuron per l prior to infection drastically decreased the number of transformed zones. The optimized protocol was used to obtain transient transformation frequencies ranging from 12% to 36% for leaf explants, 15% to 42% for epicotyls. Initial evidence of transformation was obtained by polymerase chain reaction and subsequently confirmed by Southern analysis of regenerated plants.

NASA Discipline Life Support Systems↗