Representational Geometries Reveal Differential Effects of Response Correlations on Population Codes in Neurophysiology and Functional Magnetic Resonance Imaging.

Two sensory neurons usually display trial-by-trial spike-count correlations given the repeated representations of a stimulus. The effects of such response correlations on population-level sensory coding have been the focal contention in computational neuroscience over the past few years. In the meantime, multivariate pattern analysis (MVPA) has become the leading analysis approach in functional magnetic resonance imaging (fMRI), but the effects of response correlations among voxel populations remain underexplored. Here, instead of conventional MVPA analysis, we calculate linear Fisher information of population responses in human visual cortex (five males, one female) and hypothetically remove response correlations between voxels. We found that voxelwise response correlations generally enhance stimulus information, a result standing in stark contrast to the detrimental effects of response correlations reported in empirical neurophysiological studies. By voxel-encoding modeling, we further show that these two seemingly opposite effects actually can coexist within the primate visual system. Furthermore, we use principal component analysis to decompose stimulus information in population responses onto different principal dimensions in a high-dimensional representational space. Interestingly, response correlations simultaneously reduce and enhance information on higher- and lower-variance principal dimensions, respectively. The relative strength of the two antagonistic effects within the same computational framework produces the apparent discrepancy in the effects of response correlations in neuronal and voxel populations. Our results suggest that multivariate fMRI data contain rich statistical structures that are directly related to sensory information representation, and the general computational framework to analyze neuronal and voxel population responses can be applied in many types of neural measurements.SIGNIFICANCE STATEMENT Despite the vast research interest in the effect of spike-count noise correlations on population codes in neurophysiology, it remains unclear how the response correlations between voxels influence MVPA in human imaging. We used an information-theoretic approach and showed that unlike the detrimental effects of response correlations reported in neurophysiology, voxelwise response correlations generally improve sensory coding. We conducted a series of in-depth analyses and demonstrated that neuronal and voxel response correlations can coexist within the visual system and share some common computational mechanisms. These results shed new light on how the population codes of sensory information can be evaluated via different neural measurements.

Decentralized Neural Circuits of Multisensory Information Integration in the Brain.

The brain combines multisensory inputs together to obtain a complete and reliable description of the world. Recent experiments suggest that several interconnected multisensory brain areas are simultaneously involved to integrate multisensory information. It was unknown how these mutually connected multisensory areas achieve multisensory integration. To answer this question, using biologically plausible neural circuit models we developed a decentralized system for information integration that comprises multiple interconnected multisensory brain areas. Through studying an example of integrating visual and vestibular cues to infer heading direction, we show that such a decentralized system is well consistent with experimental observations. In particular, we demonstrate that this decentralized system can optimally integrate information by implementing sampling-based Bayesian inference. The Poisson variability of spike generation provides appropriate variability to drive sampling, and the interconnections between multisensory areas store the correlation prior between multisensory stimuli. The decentralized system predicts that optimally integrated information emerges locally from the dynamics of the communication between brain areas and sheds new light on the interpretation of the connectivity between multisensory brain areas.

A Medicago truncatula lncRNA MtCIR1 negatively regulates response to salt stress.

MAIN CONCLUSION: A lncRNA MtCIR1 negatively regulates the response to salt stress in Medicago truncatula seed germination by modulating seedling growth and ABA metabolism and signaling by enhancing Na+ accumulation. Increasing evidence suggests that long non-coding RNAs (lncRNAs) are involved in the regulation of plant tolerance to varying abiotic stresses. A large number of lncRNAs that are responsive to abiotic stress have been identified in plants; however, the mechanisms underlying the regulation of plant responses to abiotic stress by lncRNAs are largely unclear. Here, we functionally characterized a salt stress-responsive lncRNA derived from the leguminous model plant M. truncatula, referred to as MtCIR1, by expressing MtCIR1 in Arabidopsis thaliana in which no such homologous sequence was observed. Expression of MtCIR1 rendered seed germination more sensitive to salt stress by enhanced accumulation of abscisic acid (ABA) due to suppressing the expression of the ABA catabolic enzyme CYP707A2. Expression of MtCIR1 also suppressed the expression of genes associated with ABA receptors and signaling. The ABA-responsive gene AtPGIP2 that was involved in degradation of cell wall during seed germination was up-regulated by expressing MtCIR1. On the other hand, expression of MtCIR1 in Arabidopsis thaliana enhanced foliar Na+ accumulation by down-regulating genes encoding Na+ transporters, thus rendering the transgenic plants more sensitive to salt stress. These results demonstrate that the M. truncatula lncRNA MtCIR1 negatively regulates salt stress response by targeting ABA metabolism and signaling during seed germination and foliar Na+ accumulation by affecting Na+ transport under salt stress during seedling growth. These novel findings would advance our knowledge on the regulatory roles of lncRNAs in response of plants to salt stress.

lncRNA MtCIR2 positively regulates plant-freezing tolerance by modulating CBF/DREB1 gene clusters.

Emerging evidence suggests that long noncoding RNAs (lncRNAs) are involved in regulation of plant response to environmental stress. CBF/DREB1s are highly conserved transcription factors that regulate response to cold stress in plants. However, very few lncRNAs were found to regulate expression of CBFs and cold tolerance in plant. Here, we identified a cold-responsive long intergenic noncoding RNA (MtCIR2) of CBF/DREB1 genes that were located in a major freezing tolerance QTL region of legume Medicago truncatula. We found that response of MtCIR2 transcription was more rapid than that of MtCBF/DREB1s during cold treatment. MtCIR2 positively regulated M. truncatula freezing tolerance, such that overexpression of MtCIR2 led to higher survival rate and lower cell membrane damage than wild-type plants, while mutation of MtCIR2 rendered the mutants more sensitive to cold stress. In addition, expression levels of MtCBF/DREB1s were up-regulated in the MtCIR2 overexpressing lines and down-regulated in the mutants. Among the MtCIR2-regulated genes, the strongest enriched genes were those involved in polysaccharide metabolic processes. In addition, we demonstrated that overexpression of MtCIR2 led to increases in contents of soluble sugars. These results highlight that MtCIR2 positively regulates tolerance to freezing by regulating MtCBF/DREB1s expression and glycometabolism in M. truncatula.

Protein kinase MtCIPK12 modulates iron reduction in Medicago truncatula by regulating riboflavin biosynthesis.

Iron (Fe) is an essential micronutrient, and deficiency in available Fe is one of the most important limiting factors for plant growth. In some species including Medicago truncatula, Fe deficiency results in accumulation of riboflavin, a response associated with Fe acquisition. However, how the plant's Fe status is integrated to tune riboflavin biosynthesis and how riboflavin levels affect Fe acquisition and utilization remains largely unexplored. We report that protein kinase CIPK12 regulates ferric reduction by accumulation of riboflavin and its derivatives in roots of M. truncatula via physiological and molecular characterization of its mutants and over-expressing materials. Mutations in CIPK12 enhance Fe accumulation and improve photosynthetic efficiency, whereas overexpression of CIPK12 shows the opposite phenotypes. The Calcineurin B-like proteins CBL3 and CBL8 interact with CIPK12, which negatively regulates the expression of genes encoding key enzymes in the riboflavin biosynthesis pathway. CIPK12 negatively regulates Fe acquisition by suppressing accumulation of riboflavin and its derivatives in roots, which in turn influences ferric reduction activity by riboflavin-dependent electron transport under Fe deficiency. Our findings uncover a new regulatory mechanism by which CIPK12 regulates riboflavin biosynthesis and Fe-deficiency responses in plants.

Reorganization of three-dimensional chromatin architecture in Medicago truncatula under phosphorus deficiency.

Emerging evidence reveals that the three-dimensional (3D) chromatin architecture plays a key regulatory role in various biological processes of plants. However, information on the 3D chromatin architecture of the legume model plant Medicago truncatula and its potential roles in the regulation of response to mineral nutrient deficiency are very limited. Using high-resolution chromosome conformation capture sequencing, we identified the 3D genome structure of M. truncatula in terms of A/B compartments, topologically associated domains (TADs) and chromatin loops. The gene density, expressional level, and active histone modification were higher in A compartments than in B compartments. Moreover, we analysed the 3D chromatin architecture reorganization in response to phosphorus (P) deficiency. The intra-chromosomal cis-interaction proportion was increased by P deficiency, and a total of 748 A/B compartment switch regions were detected. In these regions, density changes in H3K4me3 and H3K27ac modifications were associated with expression of P deficiency-responsive genes involved in root system architecture and hormonal responses. Furthermore, these genes enhanced P uptake and mobilization by increasing root surface area and strengthening signal transduction under P deficiency. These findings advance our understanding of the potential roles of 3D chromatin architecture in responses of plants in general, and in particular in M. truncatula, to P deficiency.

The roles of stomatal morphologies in transpiration and nutrient transportation between grasses and forbs in a temperate steppe.

BACKGROUND AND AIMS: Grasses and forbs are dominant functional groups in temperate grasslands and display substantial differences in many biological traits, especially in root and stomatal morphologies, which are closely related to the use of water and nutrients. However, few studies have investigated the differences in nutrient accumulation and stomatal morphology-mediated transportation of water and nutrients from roots to shoots comparatively between the two functional groups. METHODS: Here, we explored the patterns of accumulation of multiple nutrients (N, P, K, Ca, Mg and S) in leaves and roots, transpiration-related processes and interactions between nutrients and transpiration at functional group levels by experiments in a temperate steppe and collection of data from the literature. KEY RESULTS: The concentrations of all the examined nutrients were obviously higher in both leaves and roots of forbs than those in grasses, especially for leaf Ca and Mg concentrations. Grasses with dumbbell-shaped stomata displayed significantly lower transpiration and stomatal conductance than forbs with kidney-shaped stomata. In contrast, grasses showed much higher water-use efficiency (WUE) than forbs. The contrasting patterns of nutrient accumulation, transpiration and WUE between grasses and forbs were less sensitive to varied environments. Leaf N, P and S concentrations were not affected by transpiration. In contrast, leaf Mg concentrations were positively correlated with transpiration in forb species. Furthermore, linear regression and principal component analysis showed that leaf Ca and Mg concentrations were positively correlated with transpiration between the two functional groups. CONCLUSIONS: Our results revealed contrasting differences in acquisition of multiple nutrients and transpiration between grasses and forbs, and that stomatal morphologies are an important driver for the distinct WUE and translocation of Ca and Mg from roots to leaves between the two functional groups in temperate steppes. These findings will contribute to our understanding of the important roles of functional traits in driving water and nutrient cycling.

Morphological and physiological traits of dominant plant species in response to mowing in a temperate steppe.

Mowing is common grassland management to feed livestock during winter by harvesting hay in many high-latitude regions in autumn. The trait-based approach has been used to explain the responses of the plant community to disturbance resulting from environmental changes and human activities. However, few studies have focused on the mechanisms underlying the responses of grassland ecosystems to mowing from the perspective of plant traits. Here, we investigated the effects of mowing on the plant community of a temperate steppe in Inner Mongolia of northern China by field experiments to dissect the trade-off between morphological and physiological traits in response to short-term (4 years) and long-term (16 years) mowing. Specifically, we evaluated the two strategies associated with the nutrient acquisition of two dominant species in response to mowing by measuring leaf and root morphological traits and physiological traits of root carboxylate exudation, arbuscular mycorrhizal fungi (AMF) colonization and soil microbial community. We found that long-term mowing, but not short-term mowing, led to an increase in species richness. In addition, mowing decreased the overall plant biomass of the grassland community, but enhanced and suppressed the growth of forbs and grasses, respectively. However, the ratio of forbs to grasses in the community was dependent on mowing duration, such that forbs became more dominant than the grasses under long-term mowing. Our results revealed that short-term mowing reduced soil microbial biodiversity and root colonization of AMF in the grass Stipa krylovii, while the root AMF colonization and carboxylate exudation in the forb Artemisia frigida were enhanced by short-term mowing. In long-term mowing, the functional traits associated with leaf resource conservation (i.e., leaf tissue density) and root resource acquisition were reduced in the grass, while the functional traits related to leaf resource acquisition and root resource conservation were increased in the forb, highlighting the species specificity and divergence in leaf and root traits in the grass and forb of temperate steppe in response to mowing. These novel findings demonstrate that physiological and morphological strategies are the main drivers for dominant species in response to mowing in temperate grasslands.

Mowing accelerates phosphorus cycling without depleting soil phosphorus pool.

Mowing, as a common grassland utilization strategy, affects nutrient status in soil by plant biomass removal. Phosphorus (P) cycle plays an important role in determining grassland productivity. However, few studies have addressed the impacts of mowing on P cycling in grassland ecosystems. Here, we investigated the effects of various mowing regimes on soil P fractions and P accumulation in plants and litters. We specifically explored the mechanisms by which mowing regulates ecosystem P cycling by linking aboveground community with soil properties. Our results showed that mowing increased soil dissolvable P concentrations, which probably met the demand for P absorption and utilization by plants, thus contributing to an increased P accumulation by plants. Mowing promoted grassland P cycling by a reciprocal relationship between plants and microbes. Short-term mowing enhanced P cycling mainly through increased root exudation-evoked the extracellular enzyme activity of microbes rather than the alternations in microbial biomass and community composition. Long-term mowing increased P cycling mainly by promoting carbon allocation to roots, thereby leading to greater microbial metabolic activity. Although mowing-stimulation of organic P mineralization lasted for 15 consecutive years, mowing did not result in soil P depletion. These results demonstrate that P removal by mowing will not necessarily lead to soil P limitation. Our findings would advance the knowledge on soil P dynamic under mowing and contribute to resource-efficient grassland management.

MicroRNA­124: an emerging therapeutic target in central nervous system disorders.

The central nervous system (CNS) consists of neuron and non-neuron cells including neural stem/precursor cells (NSPCs), neuroblasts, glia cells (mainly astrocyte, oligodendroglia and microglia), which thereby form a precise and complicated network and exert diverse functions through interactions of numerous bioactive ingredients. MicroRNAs (miRNAs), with small size approximately ~ 21nt and as well-documented post-transcriptional key regulators of gene expression, are a cluster of evolutionarily conserved endogenous non-coding RNAs. More than 2000 different miRNAs has been discovered till now. MicroRNA-124(miR-124), the most brain-rich microRNA, has been validated to possess important functions in the central nervous system, including neural stem cell proliferation and differentiation, cell fate determination, neuron migration, synapse plasticity and cognition, cell apoptosis etc. According to recent studies, herein, we provide a review of this conversant miR-124 to further understand the potential functions and therapeutic and clinical value in brain diseases.

Novel Information-Driven Smoothing Spline Linearization Method for High-Precision Displacement Sensors Based on Information Criterions.

A noise-resistant linearization model that reveals the true nonlinearity of the sensor is essential for retrieving accurate physical displacement from the signals captured by sensing electronics. In this paper, we propose a novel information-driven smoothing spline linearization method, which innovatively integrates one new and three standard information criterions into a smoothing spline for the high-precision displacement sensors' linearization. Using theoretical analysis and Monte Carlo simulation, the proposed linearization method is demonstrated to outperform traditional polynomial and spline linearization methods for high-precision displacement sensors with a low noise to range ratio in the 10-5 level. Validation experiments were carried out on two different types of displacement sensors to benchmark the performance of the proposed method compared to the polynomial models and the the non-smoothing cubic spline. The results show that the proposed method with the new modified Akaike Information Criterion stands out compared to the other linearization methods and can improve the residual nonlinearity by over 50% compared to the standard polynomial model. After being linearized via the proposed method, the residual nonlinearities reach as low as ±0.0311% F.S. (Full Scale of Range), for the 1.5 mm range chromatic confocal displacement sensor, and ±0.0047% F.S., for the 100 mm range laser triangulation displacement sensor.

Carbonate-Induced Chemical Reductants Are Responsible for Iron Acquisition in Strategy I Wild Herbaceous Plants Native to Calcareous Grasslands.

Significant progress has been made in understanding Strategy I iron (Fe) acquisition using crop/model plants under controlled conditions in laboratories. However, plant species native to calcareous soils may have evolved unique strategies for adaptation to high carbonate/pH-induced Fe deficiency. Until now, little information is available on the Fe acquisition mechanisms in these plants. Here, we explored the Fe acquisition mechanisms in wild dicot species native to calcareous grasslands, by monitoring the Fe nutrition-related rhizosphere processes in field and greenhouse conditions. Most of these wild species displayed comparable shoot Fe concentration to those of crops, and some dicots actually accumulated very high shoot Fe. However, these species did not exhibit ferric reductase oxidase (FRO)-dependent Strategy I responses to Fe deficiency, including visual rhizosphere acidification and increased Fe3+ reduction. In contrast, chemical reductants exuded by roots of dicots were responsible for Fe3+ reduction in these wild plants. These features were not observed in the FRO-dependent Strategy I crop plant cucumber. Neither leaf chlorophyll nor shoot/root Fe was depressed by 10% CaCO3 application in all the examined wild species. Furthermore, their root exudation was significantly activated by CaCO3, leading to an increased Fe3+ reduction. We show that chemical reductant-mediated Fe3+ reduction occurs preferentially in these wild dicots and that these mechanisms are not sensitive to high soil carbonate/pH. Our findings support that Fe acquisition in Strategy I wild plants native to calcareous soils is substantially different from the enzyme-dependent system of Strategy I plants.

Using anatomical traits to understand root functions across root orders of herbaceous species in a temperate steppe.

Root anatomical traits play crucial roles in understanding root functions and root form-function linkages. However, the root anatomy and form-function linkages of monocotyledonous and dicotyledonous herbs remain largely unknown. We measured order-based anatomical traits and mycorrhizal colonization rates of 32 perennial herbs of monocotyledons and dicotyledons in a temperate steppe. For monocots, relative constant proportion of cortex and mycorrhizal colonization rates, but increased cell-wall thickening of the endodermis and proportion of stele were observed across root orders, indicating a slight reduction in absorption capacity and improvement in transportation capacity across orders. For dicots, the cortex and mycorrhizal colonization disappeared in the fourth-order and/or fifth-order roots, whereas the secondary vascular tissue increased markedly, suggesting significant transition of root functions from absorption to transportation across root orders. The allometric relationships between stele and cortex differed across root orders and plant groups, suggesting different strategies to coordinate the absorption and transportation functions among plant groups. In summary, our results revealed different functional transition patterns across root orders and distinct strategies for coordinating the absorption and transportation of root system between monocots and dicots. These findings will contribute to our understanding of the root form and functions in herbaceous species.

An integrated belowground trait-based understanding of nitrogen-driven plant diversity loss.

Belowground plant traits play important roles in plant diversity loss driven by atmospheric nitrogen (N) deposition. However, the way N enrichment shapes plant microhabitats by patterning belowground traits and finally determines aboveground responses is poorly understood. Here, we investigated the rhizosheath trait of 74 plant species in seven N-addition simulation experiments across multiple grassland ecosystems in China. We found that rhizosheath formation differed among plant functional groups and contributed to changes in plant community composition induced by N enrichment. Compared with forb species, grass and sedge species exhibited distinct rhizosheaths; moreover, grasses and sedges expanded their rhizosheaths with increasing N-addition rate which allowed them to colonize belowground habitats. Grasses also shaped a different microenvironment around their roots compared with forbs by affecting the physicochemical, biological, and stress-avoiding properties of their rhizosphere soil. Rhizosheaths act as a "biofilm-like shield" by the accumulation of protective compounds, carboxylic anions and polysaccharides, determined by both plants and microorganisms. This enhanced the tolerance of grasses and sedges to stresses induced by N enrichment. Conversely, forbs lacked the protective rhizosheaths which renders their roots sensitive to stresses induced by N enrichment, thus contributing to their disappearance under N-enriched conditions. This study uncovers the processes by which belowground facilitation and trait matching affect aboveground responses under conditions of N enrichment, which advances our mechanistic understanding of the contribution of competitive exclusion and environmental tolerance to plant diversity loss caused by N deposition.

Certification of Genuine Multipartite Entanglement with General and Robust Device-Independent Witnesses.

Genuine multipartite entanglement represents the strongest type of entanglement, which is an essential resource for quantum information processing. Standard methods to detect genuine multipartite entanglement, e.g., entanglement witnesses, state tomography, or quantum state verification, require full knowledge of the Hilbert space dimension and precise calibration of measurement devices, which are usually difficult to acquire in an experiment. The most radical way to overcome these problems is to detect entanglement solely based on the Bell-like correlations of measurement outcomes collected in the experiment, namely, device independently. However, it is difficult to certify genuine entanglement of practical multipartite states in this way, and even more difficult to quantify it, due to the difficulty in identifying optimal multipartite Bell inequalities and protocols tolerant to state impurity. In this Letter, we explore a general and robust device-independent method that can be applied to various realistic multipartite quantum states in arbitrary finite dimension, while merely relying on bipartite Bell inequalities. Our method allows us both to certify the presence of genuine multipartite entanglement and to quantify it. Several important classes of entangled states are tested with this method, leading to the detection of genuinely entangled states. We also certify genuine multipartite entanglement in weakly entangled Greenberger-Horne-Zeilinger states, showing that the method applies equally well to less standard states.

Genome-wide analysis of the Glutathione S-Transferase family in wild Medicago ruthenica and drought-tolerant breeding application of MruGSTU39 gene in cultivated alfalfa.

KEY MESSAGE: Transformation of MruGSTU39 in M. ruthenica and alfalfa enhanced growth and survival of transgenic plants by up-regulating GST and glutathione peroxidase activity to detoxify ROS under drought stress. Glutathione S-transferases (GSTs) are ubiquitous supergene family which play crucial roles in detoxification of reactive oxygen species (ROS). Despite studies on GSTs, few studies have focused on them in perennial, wild plant species with high tolerance to environmental stress. Here, we identified 66 MruGST genes from the genome of Medicago ruthenica, a perennial legume species native to temperate grasslands with high tolerance to environmental stress. These genes were divided into eight classes based on their conserved domains, phylogenetic tree and gene structure, with the tau class being the most numerous. Duplication analysis revealed that GST family in M. ruthenica was expanded by segmental and tandem duplication. Several drought-responsive MruGSTs were identified by transcriptomic analyses. Of them, expression of MruGSTU39 was up-regulated much more in a tolerant accession by drought stress. Transformation of MruGSTU39 in M. ruthenica and alfalfa (Medicago sativa) enhanced growth and survival of transgenic seedlings than their wild-type counterparts under drought. We demonstrated that MruGSTU39 can detoxify ROS to reduce its damage to membrane by up-regulating activities of GST and glutathione peroxidase. Our findings provide full-scale knowledge on GST family in the wild legume M. ruthenica with high tolerance to drought, and highlight improvement tolerance of legume forages to drought using genomic information of M. ruthenica.

A nomogram to predict prolonged postoperative ileus after intestinal resection for Crohn's disease.

PURPOSE: We aim to identify the risk factors of PPOI in patients with CD and create a nomogram for prediction of PPOI for CD. METHODS: Data on 462 patients who underwent partial intestinal resection for CD in Jin-ling Hospital between January 2019 and June 2021 were retrospectively collected. Univariate and multivariate analyses were performed to determine the risk factors for PPOI and we used the risk factors to create a nomogram. Then we used the Bootstrap-Concordance index and calibration diagrams to evaluate the performance of the Nomogram. Decision curve analysis was performed to evaluate clinical practicability of the model. RESULTS: The incidence of PPOI was 27.7% (n of N). Course of CD ≥ 10 years, operation time ≥ 154 min, the lowest mean arterial pressure ≤ 76.2 mmHg, in-out balance per body weight ≥ 22.90 ml/kg, post-op day 1 infusion ≥ 2847 ml, post-op lowest K+ ≤ 3.75 mmol/L, and post-op day 1 procalcitonin ≥ 2.445 ng/ml were identified as the independent risk factors of PPOI in patients with CD. The nomogram we created by these risk factors presented with good discriminative ability (concordance index 0.723) and was moderately calibrated (bootstrapped concordance index 0.704). The results of decision curve analysis showed that the nomogram was clinically effective within probability thresholds in the 8 to 66% range. CONCLUSION: The nomogram we developed is helpful to evaluate the risk of developing PPOI after partial intestinal resection for CD. Clinicians can take more necessary measures to prevent PPOI in CD's patients or at least minimize the incidence.

The genome of a wild Medicago species provides insights into the tolerant mechanisms of legume forage to environmental stress.

BACKGROUND: Medicago ruthenica, a wild and perennial legume forage widely distributed in semi-arid grasslands, is distinguished by its outstanding tolerance to environmental stress. It is a close relative of commonly cultivated forage of alfalfa (Medicago sativa). The high tolerance of M. ruthenica to environmental stress makes this species a valuable genetic resource for understanding and improving traits associated with tolerance to harsh environments. RESULTS: We sequenced and assembled genome of M. ruthenica using an integrated approach, including PacBio, Illumina, 10×Genomics, and Hi-C. The assembled genome was 904.13 Mb with scaffold N50 of 99.39 Mb, and 50,162 protein-coding genes were annotated. Comparative genomics and transcriptomic analyses were used to elucidate mechanisms underlying its tolerance to environmental stress. The expanded FHY3/FAR1 family was identified to be involved in tolerance of M. ruthenica to drought stress. Many genes involved in tolerance to abiotic stress were retained in M. ruthenica compared to other cultivated Medicago species. Hundreds of candidate genes associated with drought tolerance were identified by analyzing variations in single nucleotide polymorphism using accessions of M. ruthenica with varying tolerance to drought. Transcriptomic data demonstrated the involvements of genes related to transcriptional regulation, stress response, and metabolic regulation in tolerance of M. ruthenica. CONCLUSIONS: We present a high-quality genome assembly and identification of drought-related genes in the wild species of M. ruthenica, providing a valuable resource for genomic studies on perennial legume forages.

Charge Transfer Gap Tuning via Structural Distortion in Monolayer 1T-NbSe2.

The Mott state in 1T-TaS2 is predicted to host quantum spin liquids (QSLs). However, its insulating mechanism is controversial due to complications from interlayer coupling. Here, we study the charge transfer state in monolayer 1T-NbSe2, an electronic analogue to TaS2 exempt from interlayer coupling, using spectroscopic imaging scanning tunneling microscopy and first-principles calculations. Monolayer NbSe2 surprisingly displays two types of star of David (SD) motifs with different charge transfer gap sizes, which are interconvertible via temperature variation. In addition, bilayer 1T-NbSe2 shows a Mott collapse by interlayer coupling. Our calculation unveils that the two types of SDs possess distinct structural distortions, altering the effective Coulomb energies of the central Nb orbital. Our calculation suggests that the charge transfer gap, the same parameter for determining the QSL regime, is tunable with strain. This finding offers a general strategy for manipulating the charge transfer state in related systems, which may be tuned into the potential QSL regime.

Root anatomical traits determined leaf-level physiology and responses to precipitation change of herbaceous species in a temperate steppe.

Root anatomy plays important roles in the control of leaf water relations. However, few studies have evaluated whether and how anatomical traits of absorptive roots influence leaf physiology of herbaceous species in a temperate grassland. We measured absorptive root anatomical traits and leaf physiological traits of 15 herbaceous species in a temperate steppe and monitored their responses to increased precipitation in a field stimulating experiment. Root anatomical and leaf physiological traits differed among monocotyledonous grasses, monocotyledonous liliaceous species and dicotyledonous forbs. The species with higher stele: root diameter, lower root diameter and cortex thickness exhibited higher transpiration rates and stomatal conductance, but lower intrinsic water-use efficiency. Increased precipitation enhanced transpiration and stomatal conductance of forbs and lilies, but it enhanced photosynthesis in lilies exclusively. The sensitive response of lilies to precipitation may be related to their large root diameter and cortex thickness. In summary, we observed distinct differences in anatomical traits of absorptive roots among plant groups in temperate steppes. These differences drove variations in leaf physiological traits and their diverse responses to precipitation change. These findings highlight the important roles of root anatomical traits in driving leaf-level physiological processes in temperate grasslands.