Model Plant Research Articles

Linking secretion and cytoskeleton in immunity- a case for Arabidopsis TGNap1.

In plants, robust defense depends on the efficient and resilient trafficking supply chains to the site of pathogen attack. Though the importance of intracellular trafficking in plant immunity has been well established, a lack of clarity remains regarding the contribution of the various trafficking pathways in transporting immune-related proteins. We have recently identified a trans-Golgi network protein, TGN-ASSOCIATED PROTEIN 1 (TGNap1), which functionally links post-Golgi vesicles with the cytoskeleton to transport immunity-related proteins in the model plant species Arabidopsis thaliana. We propose new hypotheses on the various functional implications of TGNap1 and then elaborate on the surprising heterogeneity of TGN vesicles during immunity revealed by the discovery of TGNap1 and other TGN-associated proteins in recent years.

Advancements in plant transformation: from traditional methods to cutting-edge techniques and emerging model species.

The ability to efficiently genetically modify plant species is crucial, driving the need for innovative technologies in plant biotechnology. Existing plant genetic transformation systems include Agrobacterium-mediated transformation, biolistics, protoplast-based methods, and nanoparticle techniques. Despite these diverse methods, many species exhibit resistance to transformation, limiting the applicability of most published methods to specific species or genotypes. Tissue culture remains a significant barrier for most species, although other barriers exist. These include the infection and regeneration stages in Agrobacterium, cell death and genomic instability in biolistics, the creation and regeneration of protoplasts for protoplast-based methods, and the difficulty of achieving stable transformation with nanoparticles. To develop species-independent transformation methods, it is essential to address these transformation bottlenecks. This review examines recent advancements in plant biotechnology, highlighting both new and existing techniques that have improved the success rates of plant transformations. Additionally, several newly emerged plant model systems that have benefited from these technological advancements are also discussed.

More than flowering: CONSTANS plays multifaceted roles in plant development and stress responses.

Plants have evolved a remarkable ability to sense and respond to changes in photoperiod, allowing adjustments to their growth and development based on seasonal and environmental cues. The floral transition is a pivotal stage in plant growth and development, signifying a shift from vegetative to reproductive growth. CONSTANS (CO), a central photoperiodic response factor conserved in various plants, mediates day-length signals to control the floral transition, although its mechanisms of action vary among plants with different day-length requirements. In addition, recent studies have uncovered roles for CO in organ development and stress responses. These pleiotropic roles in model plants and crops make CO a potentially fruitful target for molecular breeding aimed at modifying crop agronomic traits. This review systematically traces research on CO, from its discovery and functional studies to the exploration of its regulatory mechanisms and newly discovered functions, providing important insight into the roles of CO and laying a foundation for future research.

Phytoplasma DNA Enrichment from Sugarcane White Leaves for Shotgun Sequencing Improvement

Sugarcane white leaf (SCWL) disease, caused by Candidatus Phytoplasma sacchari, poses a significant threat to sugarcane cultivation. An obligate parasite, phytoplasma is difficult to culture in laboratory conditions, making the isolation of its DNA from the massive amount of plant host DNA extremely challenging. Yet, the appropriate amount and quality of plant microbiome-derived DNA are key for high-quality DNA sequencing data. Here, a simple, cost-effective, alternative method for DNA isolation was applied using a guanidine-HCl-hydroxylated silica (GuHCl-Silica)-based method and microbiome DNA enrichment based on size-selective low-molecular-weight (LMW) DNA by PEG/NaCl precipitation. qPCR analysis revealed a significant enrichment of phytoplasma DNA in the LMW fraction. Additionally, the NEBNext Microbiome DNA enrichment kit was utilized to further enrich microbial DNA, demonstrating a remarkable increase in the relative abundance of phytoplasma DNA to host DNA. Shotgun sequencing of the isolated DNA gave high-quality data on the metagenome assembly genome (MAG) of Ca. Phytoplasma sacchari SCWL with completeness at 95.85 and 215× coverage. The results indicate that this combined approach of PEG/NaCl size selection and microbiome enrichment is effective for obtaining high-quality genomic data from phytoplasma, surpassing previous methods in efficiency and resource utilization. This low-cost method not only enhances the recovery of microbiome DNA from plant hosts but also provides a robust framework for studying plant pathogens in complex plant models.

Functional analysis of TkWRKY33: A key regulator in drought-induced natural rubber synthesis in Taraxacum kok-saghyz

WRKY proteins, which form a transcription factor superfamily that responds to jasmonic acid (JA) signals, regulate various developmental processes and stress responses in plants, including Taraxacum kok-saghyz (TKS). TKS serves as an ideal model plant for studying rubber production and lays the foundation for a comprehensive understanding of JA-mediated regulation of natural rubber synthesis. In the present study, we screened and identified a valuable transcription factor, TkWRKY33, based on transcriptome data from TKS in response to JA. We investigated its role in the regulation of natural rubber synthesis within the JA signaling pathway and its function in response to drought stress. Through protein-protein interactions and transcriptional regulation analysis, we found that TkWRKY33 may regulate natural rubber synthesis through the JA-TkMPK3-TkWRKY33-(TkGGPS5/TkACAT8) cascade pathway, possibly by participating in JA-activated mitogen-activated protein kinase (MAPK) signaling. Overexpression of TkWRKY33 in tobacco, along with functional analysis of drought resistance and comparative analysis of natural rubber content after drought stress, revealed that TkWRKY33 not only enhances plant drought resistance by regulating the expression of genes related to reactive oxygen species (ROS) scavenging through the JA signaling pathway, but also has a close relationship with the signal transduction pathway mediated by the JA hormone in regulating natural rubber synthesis.The TkWRKY33 is recognized as a valuable transcription factor, which likely plays a role in regulating natural rubber biosynthesis through the JA-activated MAPK cascade signaling pathway JA-TkMPK3-TkWRKY33-(TkGGPS5/TkACAT8).

GmWRKY33A positively regulates disease resistance in soybean (Glycine max)

The WRKY transcription factor gene family is a plant-specific transcription factor that plays important roles defense responses. Studies in model plant Arabidopsis demonstrated that WRKYs function downstream of mitogen activated-protein kinase (MAPK) signaling cascade and participate in defense responses through activating the expression of defense-related genes. However, the roles of WRKYs in defense responses have not been previously investigated in paleopolyploidy soybean. Bioinfomatic analysis revealed that there are three pair of GmWRKY33 genes in the soybean genome. The identity of first two pair of GmWRKY33 genes is greater than 84% (named as GmWRKY33A). The identity of genes within the same pair is greater than 95%. A 300 bp fragment highly homologous to these four GmWRKY33A was chosen to clone into bean pod mosaic virus (BPMV)-based silencing vector (BPMV-VIGS) to achieve the goal of silencing four GmWRKY33A genes simultaneously. In this study, we simultaneously silenced four homologous genes of GmWRKY33A using a bean pod mottle virus (BPMV) vector carrying a single fragment of GmWRKY33A. Comparing the silenced plants with the vector control plants, no evident morphological phenotypes were observed. However, the GmWRKY33A-silenced plants exhibited significantly reduced resistance to Pseudomonas syringae pv. glycinea (Psg), Xanthomonas axonopodis pv. glycine (Xag), as well as to soybean mosaic virus (SMV). Furthermore, we demonstrated that silencing these GmWRKY33A genes significantly inhibited the activation of GmMPK3/GmMPK6 induced by Psg infection. Collectively, our results suggest that GmWRKY33As are involved in soybean immunity through regulating the transcription of GmMPK3/6 genes or activating the kinase activities of GmMPK3/6. Taken together, our results demonstrated that GmWRKY33As are positive regulators of soybean immune responses.

Phylogenomic analysis of glutamine synthetase gene family in Helianthus annuus L.

Glutamine synthetase is one of the predominant enzymes in nitrogen metabolism. In developing leaves, glutamine is mainly produced in chloroplasts by the activity of the GS2 isoenzyme. It catalyzes glutamine synthesis from glutamate and ammonia in an ATP-dependent reaction. The genes encoding glutamine synthetase play a crucial role in ammonia and glutamate detoxification, acid-base homeostasis, cell signaling, and cell proliferation. The gene family responsible for producing glutamine synthetase has been previously documented in model plants like Arabidopsis. Nevertheless, there has been no exploration into its existence and attributes in oilseed crops like sunflower (Helianthus annuus L.). This study thoroughly analyzes, gene structure, conserved motifs, chromosomal location, phylogenetic relationships, and expression patterns to identify the glutamine synthetase genes in H. annuus. Our findings unveiled 19 genes encoding glutamine synthetase within the H. annuus genome. These genes were distributed across 11 chromosomes of H. annuus. Furthermore, we examined the expression patterns of all the HaGS genes using RNA-seq datasets, specifically focusing on their response to biotic and abiotic stress conditions. Under biotic stress, H. annuus expresses genes for mycorrhizal fungi named Rhizoglomus irregulare at four days post inflorescence (dpi) and 16 dpi. Under abiotic stress, the effect of drought and hormones was investigated. In drought, one gene, HaGS6D, showed the highest expression in the leaf. Meanwhile, in roots, gene HaGS7B showed the highest expression. Under hormonal stress, the effects of auxin, brassinosteroid, and cytokinin were studied on the leaf. For auxin, the gene HaGS7C showed the highest expression. For brassinosteroid, the gene HaGS7D showed the highest expression; for cytokinin, the gene HaGS6E showed the highest expression. Thus, these findings can significantly contribute to our understanding of the arrangement of glutamine synthetase genes in H. annuus and offer valuable insights for developing of drought-resistant cultivars of this species.

Considering Carbon–Hydrogen Coupled Integrated Energy Systems: A Pathway to Sustainable Energy Transition in China Under Uncertainty

The low-carbon construction of integrated energy systems is a crucial path to achieving dual carbon goals, with the power-generation side having the greatest potential for emissions reduction and the most direct means of reduction, which is a current research focus. However, existing studies lack the precise modeling of carbon capture devices and the cascaded utilization of hydrogen energy. Therefore, this paper establishes a carbon capture power plant model based on a comprehensive, flexible operational mode and a coupled model of a two-stage P2G (Power-to-Gas) device, exploring the “energy time-shift” characteristics of the coupled system. IGDT (Information Gap Decision Theory) is used to discuss the impact of uncertainties on the power generation side system. The results show that by promoting the consumption of clean energy and utilizing the high energy efficiency of hydrogen while reducing reliance on fossil fuels, the proposed system not only meets current energy demands but also achieves a more efficient emission reduction, laying a solid foundation for a sustainable future. By considering the impact of uncertainties, the system ensures resilience and adaptability under fluctuating renewable energy supply conditions, making a significant contribution to the field of sustainable energy transition.

Identifying and quantifying the contribution of maize plant traits to nitrogen uptake and use through plant modelling

Abstract Breeding for high nitrogen use efficient crops can contribute to maintaining or even increasing yield with less nitrogen. Nitrogen use is co-determined by N uptake and physiological use efficiency (PE, biomass per unit of N taken up), to which soil processes as well as plant architectural, physiological and developmental traits contribute. The relative contribution of these crop traits to N use is not well known but relevant to identify breeding targets in important crop species like maize. To quantify the contribution of component plant traits to maize N uptake and use, we used a functional-structural plant model. We evaluated the effect of varying both shoot and root traits on crop N uptake across a range of nitrogen levels. Root architectural traits were found to play a more important role in root N uptake than physiological traits. Phyllochron determined the structure of the shoot through changes in source: sink ratio over time which, in interaction with light and temperature, resulted in a significant effect on PE and N uptake. Photosynthesis traits were more relevant to biomass accumulation rather than yield, especially under high nitrogen conditions. The traits identified in this study are potential targets in maize breeding for improved crop N uptake and use.

Methodical and algorithmic aspects of mathematical modeling of a screw aircraft power plant

The article describes the solution of a scientific problem that consists in expanding the functionality of the program “Calculation of the traction-economic and mass-specific characteristics of the power plant and aircraft motion parameters” through the introduction of additional algorithms and mathematical models for calculating the altitude-speed characteristics of screw aircraft power installations. At the same time, an internal calculation of the aircraft propeller thrust is used according to experimental aerodynamic coefficients, which makes it possible to increase the efficiency and reliability of complex theoretical studies of power plants of various types as part of aircraft at the stage of external design. A description is given of the developed algorithms: an algorithm for converting power on the output shaft of a gas turbine engine into thrust of an aircraft power plant; a mathematical model of a propeller that provides calculation of its thrust from experimental aerodynamic coefficients; an algorithm for determining the thrust of the power plant, taking into account the compressibility of the air and the interaction of the propeller and the elements of the airframe of the aircraft. Some features of the mathematical modeling of an aircraft propeller are revealed, in particular, the principle of propeller control by influencing the blade angle and rotational speed depending on the aircraft flight speed and a method for constructing the field of aerodynamic characteristics of an aircraft propeller in a wide range of blade angle and speed coefficient. In conclusion, the results of verification of the modified program are presented with an analysis of the obtained altitude-speed characteristics.

Responses of yield, CH4 and N2O emissions to ratoon rice cropping and different management practices

Context or problemConversion from single rice (SR) or double rice (DR) to ratoon rice (RR) is gaining growing popularity in China. Yet, a quantitative synthesis of their impact on greenhouse gas (GHG, including methane (CH4) and nitrous oxide (N2O)) emissions and grain yield has not been conducted. Objective or research questionThe objective was to evaluate the effects of conversion from SR or DR to RR on CH4 and N2O emissions, grain yield, global warming potential (GWP), and greenhouse gas intensity (GHGI) and to investigate the potential responses to different operating practices [alternate wetting-drying irrigation, nitrogen management, rice variety selection, and their multiple treatments (multiple measures)] in RR fields (oRR). MethodsIn this study, a comprehensive meta-analysis of 571-paired measurements from ratoon rice fields was conducted. ResultsOur results showed that the conversion from SR to RR significantly increased CH4 emissions, grain yield, and GWP by 35.4 %, 30.6 %, and 43.3 %, respectively. In contrast, the conversion from DR to RR decreased CH4 emissions, grain yield, and GWP by 23.2 %, 7.4 %, and 30.0 %, respectively. Interestingly, both conversions from SR or DR to RR did not affect N2O emissions but reduced GHGI in paddy fields, suggesting that RR provided an economically and ecologically sustainable rice planting model. Furthermore, on average, oRR further decreased CH4 and N2O emissions and GHGI from RR fields but did not affect grain yield. Among the existing management practices, the overall effect of multiple measures was better than that of alternate wetting-drying irrigation, nitrogen management, and rice variety selection. ConclusionsOverall, ratoon rice cropping decreased CH4 emissions and maintained rice grain yield. However, it is also necessary to further implement comprehensive cultivation strategies in the future to maximize the benefits of grain yield and GHG emissions reduction.

The Present State and Impact of AI-Driven Computational Tools for Predicting Plant Protein Structures.

Several key functions of plants, such as photosynthesis, nutrient transport, disease resistance, and abiotic tolerance, are manifested by several classes of proteins. Prediction of 3- dimensional (3-D) structures of proteins and their working mechanisms can have a profound impact on plant proteomics research and could help improve key agricultural traits in crop plants. This review aims to present the current status of plant protein structure determination and discuss the way forward. Most experimentally proven protein structures are available only for the model plant Arabidopsis thaliana. Most of the key crop plants have only a few hundred or fewer experimentally proven 3-D structures. Fewer than 1% of the protein sequences in the majority of plants have had their 3D structures experimentally determined, and A. thaliana is the sole plant with the highest percentage of 1.4 % of protein sequences with experimentally determined structures. AI-based protein structure prediction tool AlphaFold has predicted models of several thousand proteins for many crop plants. In AlphaFold predicted protein models, soybean has the highest percentage (65%) of its UniProt protein sequences with predicted models, and a few other crop plants have also a considerable percentage of its UniProt sequences with AlphaFold predicted models. AlphaFold might help predict models and bridge the gap in plant structure determination studies. Protein structure information might lead to engineering key residues to improve the agronomical performance of crop plants.

COMPUTER MODELING OF TRANSIENT ELECTROMECHANICAL PROCESSES IN A WIND POWER PLANT WITH A MAGNETIC GEARBOX

In this work, a computer Simulink model of a wind power plant has been developed, which uses a magnetic gearbox instead of a mechanical gearbox and also contains a synchronous permanent magnet generator. A separate Simulink model of a magnetic gearbox built on the basis of a modulated magnetic field in the air gap was developed, which al-lows to study the stability of its operation both in steady-state and transient modes. Calculations of various dynamic modes of the wind power plant’s operation were carried out, based on the developed model, such as the starting mode, an instantaneous increase in the wind speed acting on the wind turbine, and an increase in the load of the electric gen-erator. According to the results of the calculations, it is shown that in transient modes, when short-term overloads oc-cur, both rotors of the magnetic gearbox can fall out of synchronous motion for a certain period of time and then, de-pending on the parameters of the gearbox (as well as its other elements), the electromechanical system either reaches a certain operating steady-state mode or loses the ability to transfer mechanical power from the wind turbine to the gen-erator. It has been shown that the use of a more powerful magnetic gearbox, with an increased value of the maximum magnetic torque, allows of a more overload-resistant operation of both: a gearbox and the wind plant as a whole. Ref-erences 9, figures 10.

Distribution and characterization of endophytic and rhizosphere bacteriome of below-ground tissues in Chinese fir plantation.

None declared.Conflict of interestPlantation of Chinese fir, a popular woody tree species, faces sustainable issues such as nutrient deficiency and increasing disease threat. Rhizosphere and endophytic bacteria play important roles in plant' nutrient absorption and stress alleviation. Our understanding on the microbiome structure and functions are proceeding rapidly in model plants and some crop species. Yet, the spatial distribution and functional patterns of the bacteriome for the woody trees remain largely unexplored. In this study, we collected rhizosphere soil, non-rhizosphere soil, fine root, thick root and primary root samples of Chinese fir, and investigated the structure and distribution of bacteriome, as well as the beneficial effects of endophytic bacterial isolates. We discovered that Burkholderia and Paraburkholderia genera were overwhelmingly enriched in rhizosphere soil and the abundance of Pseudomonas genus was significantly enhanced in fine root. By isolating and testing the nutrient absorption and pathogen antagonism functions of representative endophytic bacteria species in Pseudomonas and Burkholderia, we noticed that P-solubilising functional isolates was enriched in fine root, while pathogen antagonism isolates was enriched in thick root. As a conclusion, our study revealed that the endophytic and rhizosphere environments of Chinese fir hold distinct structure and abundance of bacteriome, with potential specific functional enrichment of some bacterial clades. These findings assist us to further study the potential regulation mechanism of endophytic functional bacteria by the host tree, which will contribute to beneficial microbe application in forestry plantation and sustainable development.

Peptide Signals Regulate Nitrogen Deficiency Adaptation of Dicotyledonous Model Plants.

Nitrogen is a crucial macroelement essential for plant growth and development. In Arabidopsis Thaliana, classical phytohormones such as auxin and cytokinin orchestrate local and systemic signalling networks coordinate plant growth and development in response to nitrogen deficiency. Nowadays, emerging signalling pathways involving small peptides like CLAVATA3/EMBRYO SURROUNDINGR REGION (CLE) and C-TERMINALLY ENCODED PEPTIDE (CEP) and their corresponding kinase receptors, also regulate Arabidopsis' adaptation to nitrogen scarcity. Unlike Arabidopsis, which adapts to nitrogen deficiency by changing root development, legumes have the unique ability to form nitrogen-fixing root nodules through symbiotic interactions with soil rhizobia. During the symbiotic nodulation in Medicago, CLE and CEP peptides and their receptors consist of an autoregulatory network governing the number of nodules in accordance with the soil nitrogen level. Additionally, other plant peptides, such as phytosulfokine (PSK) and root meristem growth factors (RGF), have been identified as new regulators of leguminous root nodule development under nitrogen-limited condition. However, the precise mechanism by which these peptides coordinate nitrogen deficiency response and the development of nitrogen-fixing organs remains to be fully elucidated. This review summarises the adaptive strategies of dicotyledons to nitrogen deficiency, with a particular focus on the regulation of Medicago nitrogen-fixing nodule development by the peptides.

Plant Growth Optimization Using Amber Light Supplemented with Different Blue Light Spectra

Blue (400–500 nm) and red (600–700 nm) light regions have been investigated for their effects on photosynthesis and plant growth, yet evidence for specific blue light wavelengths in plant research is lacking. Investigations into amber (595 nm) light are similarly limited. To ‘shed light’ on these two important wavelengths, this study investigated the combined effects of blue and amber light on plant growth and development in two model plants: tomato (Solanum lycopersicum cv. Beefsteak) and lettuce (Lactuca sativa cv. Breen). Plant growth responses were determined with four light treatments: B+BA (blue + broad amber, 455–602 nm), RB-NA (royal blue + narrow amber, 430–602 nm), RB-BA (royal blue + broad amber, 423–595 nm), and high-pressure sodium at a PPFD of 250 µmol m−2 s−1. After 21 days, the highest fresh and dry mass for both plant species was obtained under the RB-BA light treatment. Shifting the blue wavelength from 430 nm to 455 nm with broad amber lighting led to 40% less fresh mass for tomatoes, whereas only an approximate 5% reduction in fresh mass was observed for lettuce plants. Our findings demonstrate that an alternate and combined blue + amber light spectrum is effective for optimizing plant productivity.

Diversity and interactions of rhizobacteria determine multinutrient traits in tomato host plants under nitrogen and water disturbances

Abstract Coevolution within the plant holobiont extends the capacity of host plants for nutrient acquisition and stress resistance. However, the role of the rhizospheric microbiota in maintaining multinutrient utilization (i.e., multinutrient traits) in the host remains to be elucidated. Multinutrient cycling index (MNC), analogous to the widely used multifunctionality index, provides a straightforward and interpretable measure of the multinutrient traits in host plants. Using tomato as a model plant, we characterized MNC (based on multiple aboveground nutrient contents) in host plants under different nitrogen and water supply regimes and explored the associations between rhizospheric bacterial community assemblages and host-plant multinutrient profiles. Rhizosphere bacterial community diversity, quantitative abundance, predicted function, and key topological features of the co-occurrence network were more sensitive to water supply than to nitrogen supply. A core bacteriome comprising 61 genera, such as Candidatus Koribacter and Streptomyces, persisted across different habitats and served as a key predictor of host-plant nutrient uptake. The MNC index increased with greater diversity and higher core taxon abundance in the rhizobacterial community, while decreasing with higher average degree and graph density of rhizobacterial co-occurrence network. Multinutrient absorption by host plants was primarily regulated by community diversity and rhizobacterial network complexity under the interaction of nitrogen and water. The high biodiversity and complex species interactions of the rhizospheric bacteriome play crucial roles in host-plant performance. This study supports the development of rhizosphere microbiome engineering, facilitating effective manipulation of the microbiome for enhanced plant benefits, which supports sustainable agricultural practices and plant health.

The Simulator of China General Nuclear Power Group (CGNPC) Delingha 50 MW Parabolic Trough Solar Thermal Power Plant

CGN Delingha 50MW parabolic trough solar power plant is China's first commercial trough solar power station. There are 190 heat collecting loops in the solar field of the power plant. Due to the mutual coupling of heat collecting loops layout location, environmental conditions, medium flow, working medium physical property changes and other factors, the hydrodynamic characteristics of the solar field are complex. In practical operation, balancing the flow of the heat absorbing medium in each loop of the large-scale trough solar thermal power plant and stabilizing the outlet medium temperature are difficult problems. Taking CGN Delingha 50MW parabolic trough solar power plant as the research object, this paper adopts the idea of modular modeling to establish the mathematical model of the main equipment in different systems of the power plant, to build the dynamic model of its solar field, steam generation system, heat storage system and steam turbine system. Based on the parallel computing function of the real-time dynamic simulation platform STAR-90, the real-time coupling calculation between different systems is realized. The error of the built model in steady-state is less than 2%, and the dynamic results of the model are in good agreement with the actual operation data. The modeling method in this paper is universal and can be a reference for dynamic modeling of other large-scale trough solar thermal power plants.

Hydrogen Measurement & Extraction at Nevada Solar One

Hydrogen was measured and extracted from the headspace gas of four expansion vessels that are components of the heat transfer fluid (HTF) subsystem in the Nevada Solar One (NSO) power plant, Boulder City, Nevada. Direct, real-time measurements of hydrogen partial pressures in the headspace gas were accomplished using the recently installed hydrogen mitigation process that was developed jointly by the National Renewable Energy Laboratory (NREL) and Acciona Energy, the owner/operator of NSO. This method combines the two functions of extracting hydrogen from the headspace gas and measuring hydrogen partial pressure in the headspace gas. During 2022 and 2023, we operated the process regularly and made real-time measurements of hydrogen partial pressures. In addition, DLR in Germany measured dissolved hydrogen concentration in the circulating HTF. These two measurements were compared via Henry’s Law and found to be consistent. Measured values also were compared to model results that were generated by the NSO plant model that was written to predict hydrogen levels in the power plant piping and components. The model predicted hourly hydrogen partial pressures in the expansion tanks for two cases - hydrogen extraction off, and hydrogen extraction on. Real-time hydrogen measurements and sampled HTF measurements were compared to hydrogen levels that were predicted for these two cases. We found good agreement between the hydrogen measurements and the modeled hydrogen for the extraction on case. These results indicate that the extraction process is working properly with its expected performance.

Engineered reduction of S-adenosylmethionine alters lignin in sorghum

BackgroundLignin is an aromatic polymer deposited in secondary cell walls of higher plants to provide strength, rigidity, and hydrophobicity to vascular tissues. Due to its interconnections with cell wall polysaccharides, lignin plays important roles during plant growth and defense, but also has a negative impact on industrial processes aimed at obtaining monosaccharides from plant biomass. Engineering lignin offers a solution to this issue. For example, previous work showed that heterologous expression of a coliphage S-adenosylmethionine hydrolase (AdoMetase) was an effective approach to reduce lignin in the model plant Arabidopsis. The efficacy of this engineering strategy remains to be evaluated in bioenergy crops.ResultsWe studied the impact of expressing AdoMetase on lignin synthesis in sorghum (Sorghum bicolor L. Moench). Lignin content, monomer composition, and size, as well as biomass saccharification efficiency were determined in transgenic sorghum lines. The transcriptome and metabolome were analyzed in stems at three developmental stages. Plant growth and biomass composition was further evaluated under field conditions. Results evidenced that lignin was reduced by 18% in the best transgenic line, presumably due to reduced activity of the S-adenosylmethionine-dependent O-methyltransferases involved in lignin synthesis. The modified sorghum features altered lignin monomer composition and increased lignin molecular weights. The degree of methylation of glucuronic acid on xylan was reduced. These changes enabled a ~20% increase in glucose yield after biomass pretreatment and saccharification compared to wild type. RNA-seq and untargeted metabolomic analyses evidenced some pleiotropic effects associated with AdoMetase expression. The transgenic sorghum showed developmental delay and reduced biomass yields at harvest, especially under field growing conditions.ConclusionsThe expression of AdoMetase represents an effective lignin engineering approach in sorghum. However, considering that this strategy potentially impacts multiple S-adenosylmethionine-dependent methyltransferases, adequate promoters for fine-tuning AdoMetase expression will be needed to mitigate yield penalty.