Root Stress Research Articles

Study on the parameters of steel plate reinforcement rib-deck crack considering local stress disturbances

Local reinforcement will change the local stiffness distribution of the component, causing perturbation effects on the local stress of the fatigue detail. Only considering the reinforcement effect may lead to excessive strengthening and induce new fatigue-prone points. For the fatigue detail of the rib-deck weld, steel plate reinforcement test and numerical simulations were conducted. The stress changes of the deck weld toe and weld root before and after reinforcement were analyzed. The influence of parameters such as steel plate length, thickness, and width on the reinforcement effect of the weld toe crack and local stress disturbance was discussed, and reasonable parameters were recommended. The results show that after the cracking of the weld toe, the stress concentration locations at the weld toe and weld root of the deck shift from the center of the specimen to the crack tip. Steel plate reinforcement can effectively restrain the crack propagation, but can lead to an increase in the stress at the deck weld root within the reinforced area. A good reinforcement effect can be achieved while the steel plate covers the crack, and further increasing the steel plate length has limited improvement on the reinforcement effect but reduces the adverse effect of steel plate reinforcement on the stress of the deck weld root. Increasing the steel plate width will increase the adverse effect of steel plate reinforcement on the deck weld root stress, and it is recommended to use steel plates with a length greater than 120 mm and a length-to-width ratio greater than 4 for reinforcement. Increasing the width of the steel plate has a relatively small effect on the reinforcement effect and the stress at the deck weld root, and steel plates with the same thickness as the deck are recommended.

GmSTOP1-3 regulates flavonoid synthesis to reduce ROS accumulation and enhance aluminum tolerance in soybean

Aluminum (Al) toxicity is a significant limiting factor for crop production in acid soils. The functions and regulatory mechanisms of transcription factor STOP1 (Sensitive to Proton Rhizotoxicity 1) family genes in Al-tolerance have been widely studied in many plant species, except for soybean. Here, expression of GmSTOP1-3 was significantly enhanced by Al stress in soybean roots. Overexpression of GmSTOP1-3 resulted in enhanced root elongation and decreased Al content, which was accompanied by increased antioxidant capacity under Al treatment. Furthermore, RNA-seq identified 498 downstream genes of GmSTOP1-3, including genes involved in flavonoid biosynthesis. Among them, the expression of chalcone synthase (GmCHS) and isoflavone synthase (GmIFS) were highly enhanced by GmSTOP1-3 overexpression. Further quantitative flavonoid metabolome analysis showed that overexpression of GmSTOP1-3 significantly increased the content of naringenin chalcone, naringenin, and genistein in soybean roots under Al treatment, which positively correlated with the expression level of the genes relative to flavonoid biosynthesis. Notably, genistein had a significant positive correlation with the expression levels of GmIFS. Combination of Dual Luciferase Complementation (LUC) and Electrophoretic Mobility Shift Assays (EMSA) revealed that GmSTOP1-3 directly bound to the promoters of GmCHS/GmIFS and activated both genes’ transcription. Taken together, these results suggest that GmSTOP1-3 enhances soybean Al tolerance partially through regulating the flavonoid synthesis.

ABA-activated low-nanomolar Ca2+-CPK signalling controls root cap cycle plasticity and stress adaptation.

Abscisic acid (ABA) regulates plant stress adaptation, growth and reproduction. Despite extensive ABA-Ca2+ signalling links, imaging ABA-induced increases in Ca2+ concentration has been challenging, except in guard cells. Here we visualize ABA-triggered [Ca2+] dynamics in diverse organs and cell types of Arabidopsis thaliana using a genetically encoded Ca2+ ratiometric sensor with a low-nanomolar Ca2+-binding affinity and a large dynamic range. The subcellular-targeted Ca2+ ratiometric sensor reveals time-resolved and unique spatiotemporal Ca2+ signatures from the initial plasma-membrane nanodomain, to cytosol, to nuclear oscillation. Via receptors and sucrose-non-fermenting1-related protein kinases (SnRK2.2/2.3/2.6), ABA activates low-nanomolar Ca2+ transient and Ca2+-sensor protein kinase (CPK10/30/32) signalling in the root cap cycle from stem cells to cell detachment. Surprisingly, unlike the prevailing NaCl-stimulated micromolar Ca2+ spike, salt stress induces a low-nanomolar Ca2+ transient through ABA signalling, repressing key transcription factors that dictate cell fate and enzymes that are crucial to root cap maturation and slough. Our findings uncover ABA-Ca2+-CPK signalling that modulates root cap cycle plasticity in adaptation to adverse environments.

Osmotic stress in roots drives lipoxygenase-dependent plastid remodeling through singlet oxygen production.

Osmotic stress, caused by the lack of water or by high salinity, is a common problem in plant roots. Osmotic stress can be reproducibly simulated with the application of solutions of the high-molecular-weight and impermeable polyethylene glycol. The accumulation of different reactive oxygen species, such as singlet oxygen, superoxide, and hydrogen peroxide, accompany this stress. Among them, singlet oxygen, produced as a byproduct of lipoxygenase activity, has been associated with limiting root growth. To better understand the source and effect of singlet oxygen, we followed its production at the cellular level in Arabidopsis (Arabidopsis thaliana). Osmotic stress initiated profound changes in plastid and vacuole structure. Confocal and electron microscopy showed that the plastids were a source of singlet oxygen accompanied by the appearance of multiple, small extraplastidic bodies that were also an intense source of singlet oxygen. A marker protein, CRUMPLED LEAF, indicated that these small bodies originated from the plastid outer membrane. Remarkably, LINOLEATE 9S-LIPOXYGENASE 5, (LOX5), was shown to change its distribution from uniformly cytoplasmic to a more clumped distribution together with plastids and the small bodies. In addition, oxylipin products of type 9 lipoxygenase increased, while products of type 13 lipoxygenases decreased. Inhibition of lipoxygenase by the SHAM inhibitor or in down-regulated lipoxygenase lines prevented cells from initiating the cellular responses, leading to cell death. In contrast, singlet oxygen scavenging halted terminal cell death. These findings underscore the reversible nature of osmotic stress-induced changes, emphasizing the pivotal roles of lipoxygenases and singlet oxygen in root stress physiology.

Novel application of cyclo(-Phe-Pro) in mitigating aluminum toxicity through oxidative stress alleviation in wheat roots

Microbial secondary metabolites are crucial in plant-microorganism interactions, regulating plant growth and stress responses. In this study, we found that cyclo(-Phe-Pro), a proline-based cyclic dipeptide secreted by many microorganisms, alleviated aluminum toxicity in wheat roots by increasing root growth, decreasing callose deposition, and decreasing Al accumulation. Cyclo(-Phe-Pro) also significantly reduced Al-induced reactive oxygen species (ROS) with H2O2, O2•-, and •OH levels decreasing by 19.1%, 42.8%, and 17.9% in root tips, thus protecting the plasma membrane from oxidative damage. Although Al stress increased the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) in wheat roots, cyclo(-Phe-Pro) application reduced these enzyme activities. However, compared to the Al treatment, cyclo(-Phe-Pro) application increased DPPH and FRAP activities by 16.8% and 14.9%, indicating increased non-enzymatic antioxidant capacity in wheat roots. We observed that Al caused the oxidation of ascorbate (AsA) and glutathione (GSH) to dehydroascorbate (DHA) and glutathione disulfide (GSSG), respectively. Under Al stress, cyclo(-Phe-Pro) treatment maintained reduced AsA and GSH levels, as well as high AsA/DHA and GSH/GSSG redox pair ratios in wheat roots. High AsA/DHA and GSH/GSSG ratios can reduce Al toxicity by neutralizing free radicals and restoring redox homeostasis via antioxidant properties. These results suggest that cyclo(-Phe-Pro) maintains ASA- and GSH-dependent redox homeostasis to alleviate oxidative and Al stress in wheat roots. Findings of this study establishes a theoretical foundation for using microbial metabolites to mitigate Al toxicity in acidic soils, highlighting their potential in sustainable agriculture.

Response and Reliability of Composite Post Insulators Under Random Earthquake

Abstract This article examines the stochastic response and seismic reliability of composite post-insulators under random seismic excitation. A random seismic motion model, tailored for power facility seismic research in China and compliant with the “Seismic Design Specification for Power Facilities” (GB50260-2013), is developed. This model accounts for both amplitude and frequency non-stationary. A nonlinear dynamic model for composite post insulators is then established, incorporating the nonlinearity at the multi-section insulator and flange connections. Numerical methods are employed for random seismic response analysis to address the non-stationary nature of seismic motion. The proposed model’s validity is confirmed by comparing it with the vibration table test results. Finally, the seismic reliability of composite post insulators, with root stress as the control criterion, is assessed using the probability density evolution method.

Analysis of tooth root three-dimensional fatigue crack initiation, propagation, and fatigue life for spur gear transmission

The gears in aviation gear systems are susceptible to fatigue fracture due to high-speed, heavy-load, and load alternation operating conditions. Therefore, a numerical calculation model with multiple mesh positions loading form has been proposed in this paper to analyze the fatigue crack initiation and propagation behavior, and to estimate the fatigue life of these gears. The fatigue life of the gear is determined by separately calculating the fatigue crack initiation life and the fatigue crack propagation life. The tooth root fatigue stress and the fatigue initiation life are calculated by the multi-axial fatigue life prediction method with the Smith-Watson-Topper criterion and the critical plane method. Afterwards, the tooth root stress–strain field is calculated in Finite element (FE) software and the stress intensity factors of the crack tip are calculated in three-dimensional (3D) crack analysis software. Then, the tooth root fatigue crack propagation trajectory and the fatigue crack propagation life are obtained separately. Finally, the influence mechanism of the loading conditions, the geometry parameters of gears, and the initial crack positions on the tooth root fatigue crack initiation life, propagation life, and fatigue crack propagation trajectory are analyzed, and a tooth fatigue test bench is built for verifying the crack propagation trajectory.

Genome-wide identification and expression analysis of CASPL gene family in Zea mays (L.).

Casparian strip membrane domain proteins like (CASPL), exhibit profound associations with root development, stress responsiveness and mineral element uptake in plants. Nonetheless, a comprehensive bioinformatics analysis of the ZmCASPL gene family in maize remains unreported. In the study, we have identified 47 ZmCASPL members at the whole-genome level, systematically classifying them into six distinct groups. Furthermore, our analysis revealed that the same group of ZmCASPL contains similar gene structures and conserved motifs. Duplication events showed whole genome duplication (WGD) and tandem duplication (TD) contribute to the generation of the ZmCASPL gene family together in maize, but the former plays a more prominent role. Furthermore, we observed that most ZmCASPL genes contain MYB-binding sites (CAACCA), which are associated with the Casparian strip. Utilizing RNA-seq data, we found that ZmCASPL21 and ZmCASPL47 are specifically highly expressed only in the roots. This finding implies that ZmCASPL21 and ZmCASPL47 may be involved in the Casparian strip development. Additionally, RNA-seq analysis illuminated that drought, salt, heat, cold stresses, low nitrogen and phosphorus conditions, as well as pathogen infection, significantly impact the expression patterns of ZmCASPL genes. RT-qPCR revealed that ZmCASPL 5/13/25/44 genes showed different expression patterns under PEG and NaCl treatments. Collectively, these findings provide a robust theoretical foundation for further investigations into the functional roles of the ZmCASPL gene family in maize.

Transcriptomic and metabolomic reveal OsCOI2 as the jasmonate-receptor master switch in rice root.

Jasmonate is an essential phytohormone involved in plant development and stress responses. Its perception occurs through the CORONATINE INSENSITIVE (COI) nuclear receptor allowing to target the Jasmonate-ZIM domain (JAZ) repressors for degradation by the 26S proteasome. Consequently, repressed transcription factors are released and expression of jasmonate responsive genes is induced. In rice, three OsCOI genes have been identified, OsCOI1a and the closely related OsCOI1b homolog, and OsCOI2. While the roles of OsCOI1a and OsCOI1b in plant defense and leaf senescence are well-established, the significance of OsCOI2 in plant development and jasmonate signaling has only emerged recently. To unravel the role of OsCOI2 in regulating jasmonate signaling, we examined the transcriptomic and metabolomic responses of jasmonate-treated rice lines mutated in both the OsCOI1a and OsCOI1b genes or OsCOI2. RNA-seq data highlight OsCOI2 as the primary driver of the extensive transcriptional reprogramming observed after a jasmonate challenge in rice roots. A series of transcription factors exhibiting an OsCOI2-dependent expression were identified, including those involved in root development or stress responses. OsCOI2-dependent expression was also observed for genes involved in specific processes or pathways such as cell-growth and secondary metabolite biosynthesis (phenylpropanoids and diterpene phytoalexins). Although functional redundancy exists between OsCOI1a/b and OsCOI2 in regulating some genes, oscoi2 plants generally exhibit a weaker response compared to oscoi1ab plants. Metabolic data revealed a shift from the primary metabolism to the secondary metabolism primarily governed by OsCOI2. Additionally, differential accumulation of oryzalexins was also observed in oscoi1ab and oscoi2 lines. These findings underscore the pivotal role of OsCOI2 in jasmonate signaling and suggest its involvement in the control of the growth-defense trade-off in rice.

Effects of salt stress on the fruit and yield quality of some selected tomato (<i>Lycopersicum esculentum</i> L.) varieties.

The growth, production, and nutritional characteristics of crops are impacted by abiotic factors such as salinity stress. The study aimed to assess the impact of salt stress on the fruit and yield characteristics of three distinct tomato cultivars, namely Rio, Dan syria, and UTC. Salt solutions with varying concentrations of NaCl were created by dissolving NaCl in deionized water. Four treatments were established, consisting of solutions with salt concentrations of 0g/L (control, without salt), 0.5g/L, 1.0g/L, and 1.5g/L. Each treatment was reproduced three times. The NaCl solutions were administered with a frequency of 7 days. The data in the study underwent Analysis of Variance (ANOVA). Rio outperformed the other varieties in terms of fruit quantity, fresh fruit weight, and fruit pericarp thickness under high salt stress, closely followed by UTC variety. The study also found that Dan syria performed better than the other varieties in terms of fresh and dry weight of shoot, as well as fresh weight of root, under mild and extreme salinity stress. However, Rio performed better than the other varieties in terms of dry weight of root under both mild and extreme salinity stress. The salt tolerance index of the Rio, UTC, and Dan Syria varieties under extreme salinity stress are 46.79%, 20.64%, and 34.70% respectively. This indicated that the Rio variety is the most salt-tolerant of the three types, with Dan Syria variety coming close.

Overexpression of the tomato pathogenesis-related gene SlPR-1.9 confers increased tolerance to salt stress in Arabidopsis thaliana

Pathogenesis-related (PR) proteins are essential components of plant defense mechanisms, responding to both biotic and abiotic stresses. Among these, PR-1 proteins feature a CAP (Cysteine-rich secretory proteins, Antigen 5, and Pathogenesis-related 1) domain, which is crucial for immune responses and pathogen defense due to its ability to stabilize protein structures and interact with various molecules. This study investigated the role of the tomato PR-1 gene SlPR-1.9 in enhancing salt tolerance in Arabidopsis thaliana. The gene’s coding sequence was cloned and transferred into Arabidopsis to create SlPR-1.9 overexpression lines. These transgenic lines, alongside wild-type plants, were exposed to salt stress (150 mM NaCl) to assess their tolerance. Morphological analysis revealed that the transgenic lines demonstrated greater resilience to salt stress compared to wild-type plants, with less severe leaf curling and color changes. Additionally, lower proline accumulation, a stress marker, in the transgenic lines indicated an enhanced adaptive response. Bioinformatics analysis of the protein encoded by SlPR-1.9, A0A3Q7HSC4, suggested a strong interaction with galactolipase. Expression analysis showed that SlPR-1.9 was mainly expressed in roots and during early fruit development, suggesting a significant role in root physiology and stress response. These findings indicate that overexpression of SlPR-1.9 can improve plant tolerance to salt stress, offering potential applications for enhancing crop resilience to environmental challenges.

Biochar solutions: Slow and fast pyrolysis effects on chromium stress in rapeseed roots

Chromium (Cr) contamination in agricultural soils, largely due to industrial activities, poses a significant threat to plant growth and productivity. This study examines the effects of Cr stress at concentrations of 100 and 200 mg of K2Cr2O7 per kg soil on rapeseed (Brassica napus) roots and evaluates the mitigating potential of biochar. Biochar, produced through both slow and fast pyrolysis and applied at 30 g per kg soil, was investigated for its ability to neutralize Cr toxicity. Our findings indicate that Cr stress significantly decreased the growth and physiological functions of rapeseed roots. However, biochar application improved soil pH, cation exchange capacity, and the uptake of essential nutrients such as nitrogen, phosphorus, potassium, calcium, and magnesium. Additionally, biochar enhanced the production of osmotic regulators like glycine betaine and soluble proteins, as well as indole acetic acid, promoting better root growth and water uptake under Cr stress. Notably, biochar reduced Cr availability and absorption in rapeseed roots, leading to lower levels of stress-related hormones such as abscisic acid, salicylic acid, and jasmonic acid. Among the biochars tested, slow pyrolysis biochar was more effective than fast pyrolysis biochar in mitigating Cr toxicity. These results highlight the potential of slow pyrolysis biochar as a sustainable strategy to alleviate Cr pollution and enhance plant resilience in contaminated soils.

Spur gear tooth root stress analysis by a 3D flexible multibody approach and a full-FE contact-based formulation

This paper proposes an original method to determine the gear tooth root stresses from a 3D finite element (FE) flexible multibody approach and a full-FE contact-based formulation. The contact problem is dealt with an augmented Lagrangian formulation whereas the analysis is performed by a preconditioned gradient solver (PCG). Tooth flank modifications are directly introduced within the 3D model. This one is thus able to take into account straightforwardly tooth bending and Hertzian-like deformations as well as the micro-geometry effect. Simulations are performed for several mesh periods, without making any assumptions about load distribution, tooth and gear blank flexibilities, and possible premature or delayed contacts between tooth pairs in quasi-static conditions. A precise distribution of tooth root stresses associated with instantaneous contacts conditions is then computed. For this study, a single stage spur gear with micro-geometry modifications corresponding to an arc-shaped profile crowning is modeled. Several output torques are considered. The obtained results are compared to those obtained using a 2D FE ISO-based model, where external forces are applied along the theoretical line of action.

Effect of rol Genes of the A4, 15834, and K599 Strains of Agrobacterium rhizogenes on Root Growth and States of the Antioxidant Systems of Transgenic Tobacco Plants Subjected to Abiotic Stress

An attempt is made to create transgenic plants using rol genes from A4, 15834, and K599 strains of A. rhizogenes. Strains A4 and 15834 transformed tobacco plants are found to display better root growth than their wild types under normal conditions and at elevated concentrations of sodium chloride or cadmium acetate. At the same time, the rol genes acquired from the K599 strain negatively affect root growth under both normal and stressful conditions (e.g., salinization, hypothermia, or excess cadmium acetate). The levels of total protein, proline, total glutathione, and superoxide dismutase activity are higher in the roots of the transgenic plants with rol genes from the A4 and 15834 strains than in nontransgenic control plants under both optimum conditions and salinization. When using rol transgenes from the K599 strain, the activities of superoxide dismutase, guaiacol peroxidase, and glutathione-S-transferase are enhanced in the roots subjected to salinization. The positive effect rol genes have on the root growth of transgenic plants could therefore be explained by their influence on components of the antioxidant system. Results suggest that using rol genes from the A4 and 15834 strains of A. rhizogenes are promising for breeding plant cultivars and liness with improved parameters of root growth and stress tolerance. At the same time, rol genes from the K599 strain appear to be inadequate for this task.

INDETERMINATE DOMAIN Transcription Factors in Crops: Plant Architecture, Disease Resistance, Stress Response, Flowering, and More

INDETERMINATE DOMAIN (IDD) genes encode plant-specific transcription factors containing a conserved IDD domain with four zinc finger motifs. Previous studies on Arabidopsis IDDs (AtIDDs) have demonstrated that these genes play roles in diverse physiological and developmental processes, including plant architecture, seed and root development, flowering, stress responses, and hormone signaling. Recent studies have revealed important functions of IDDs from rice and maize, especially in regulating leaf differentiation, which is related to the evolution of C4 leaves from C3 leaves. Moreover, IDDs in crops are involved in the regulation of agriculturally important traits, including disease and stress resistance, seed development, and flowering. Thus, IDDs are valuable targets for breeding manipulation. This review explores the role of IDDs in plant development, environmental responses, and evolution, which provides idea for agricultural application.

The roles of cell wall polysaccharides in response to waterlogging stress in Brassica napus L. root

BackgroundBrassica napus L. (B. napus) is susceptible to waterlogging stress during different cultivation periods. Therefore, it is crucial to enhance the resistance to waterlogging stress to achieve a high and stable yield of B. napus.ResultsHere we observed significant differences in the responses of two B. napus varieties in root under waterlogging stress. The sensitive variety (23651) exhibited a more pronounced and rapid reduction in cell wall thickness and root integrity compared with the tolerant variety (Santana) under waterlogging stress. By module clustering analysis based on transcriptome data, we identified that cell wall polysaccharide metabolism responded to waterlogging stress in root. It was found that pectin content was significantly reduced in the sensitive variety compared with the tolerant variety. Furthermore, transcriptome analysis revealed that the expression of two homologous genes encoding polygalacturonase-inhibiting protein 2 (PGIP2), involved in polysaccharide metabolic pathways, was highly upregulated in root of the tolerant variety under waterlogging stress. BnaPGIP2s probably confer waterlogging resistance by inhibiting the activity of polygalacturonases (PGs), which in turn reduces the degradation of the pectin backbone polygalacturonic acid.ConclusionsOur findings demonstrate that cell wall polysaccharides in root plays a vital role in response to the waterlogging stress and provide a theoretical foundation for breeding waterlogging resistance in B. napus varieties.

Stress Analysis of Periodontal Tissue in en Masse Retraction With Integration of Maxillary Anterior Teeth: A Three-Dimensional Finite Element Method Study.

To simulate the en masse traction technique with the integration (EMTI) of six maxillary anterior teeth using a finite element model (FEM) and explore various protocols for maxillary protrusion. The study aimed to investigate root displacement and stress distribution in the periodontal ligament (PDL) by varying the retraction position and direction of EMTI applied to the maxillary anterior teeth. No actual participants were involved. The FEM model included six teeth (central and lateral incisors and canines) with a PDL thickness of 0.3 mm. The model encompassing the alveolar bone (ALB) and EMTI had 180,528 elements and 47,836 nodes. The EMTI integrated six anterior teeth via a 0.9-mm-diameter stainless steel lingual wire, equipped with three moment arms extending toward the root apex: one midline (central arm) and two distal to the canines (lateral arms). The position and direction of the traction force applied to the three moment arms of the EMTI were varied to assess crown and apex displacement, as well as PDL stress. Lingual tipping was consistent across all protocols, emphasizing controlled incisor tipping. The application of horizontal traction at 10 mm and traction at 7 mm from the central and lateral arms of the EMTI, respectively, demonstrated the most uniform stress distribution across the PDL of all six anterior teeth. The FEM analysis results suggest that the new EMTI method, which retracts the maxillary anterior teeth as a unit, is effective for tooth movement and PDL stress distribution. The EMTI technique, with its specific traction protocols and emphasis on controlled tipping, appears to be a promising approach for addressing maxillary protrusions.

Spermidine augments salt stress resilience in rice roots potentially by enhancing OsbZIP73’s RNA binding capacity

BackgroundRice is a staple crop for over half of the global population, but soil salinization poses a significant threat to its production. As a type of polyamine, spermidine (Spd) has been shown to reduce stress-induced damage in plants, but its specific role and mechanism in protecting rice roots under salt stress require further investigation.ResultsThis study suggested spermidine (Spd) mitigates salt stress on rice root growth by enhancing antioxidant enzyme activity and reducing peroxide levels. Transcriptomic analysis showed that salt stress caused 333 genes to be upregulated and 1,765 to be downregulated. However, adding Spd during salt treatment significantly altered this pattern: 2,298 genes were upregulated and 844 were downregulated, which indicated Spd reverses some transcriptional changes caused by salt stress. KEGG pathway analysis suggested that Spd influenced key signaling pathways, including MAPK signaling, plant hormone signal transduction, and phenylalanine metabolism. Additionally, the bZIP transcription factor OsbZIP73 was upregulated after Spd treatment, which is confirmed by Western blot. Further insights into the interaction between OsbZIP73 and Spd were gained through fluorescence polarization experiments, showing that Spd enhances protein OsbZIP73’s affinity for RNA. Functional enrichment analyses revealed that OsPYL1, OsSPARK1, and various SAUR family genes involved in Spd-affected pathways. The presence of G/A/C-box elements in these genes suggests they are potential targets for OsbZIP73.ConclusionsOur findings suggest a strategy of using spermidine as a chemical alleviator for salt stress and provide insights into the regulatory function of OsbZIP73 in mitigating salt stress in rice roots.

Balancing roles between phosphatidylinositols and sphingolipids in regulating immunity and ER stress responses in pi4kβ1,2.

Plant immune regulation is complex. In addition to proteins, lipid molecules play critical roles in modulating immune responses. The mutant pi4kβ1,2 is mutated in two phosphatidylinositol 4-kinases PI4Kβ1 and β2 involved in the biosynthesis of phosphatidylinositol 4-phosphate (PI4P). The mutant displays autoimmunity, short roots, aberrant root hairs, and a heightened sensitivity to ER stress. In a forward genetic screen designed to dissect pi4kβ1,2 autoimmunity, we found that Orosomucoid-like 1 (ORM1) is required for the phenotypes of pi4kβ1,2, including short root and ER stress sensitivity. The orm1 mutations lead to increased long-chain base and ceramide levels in the suppressors. We also found that the basic region/leucine Zipper motif (bZIP) 28 and 60 transcription factors, central regulators of ER stress response, are required for its autoimmunity and root defect. In comparison, the defense-related phytohormones salicylic acid (SA) and N-hydroxypipecolic acid (NHP) are required for its autoimmunity but plays a minor role in its root phenotypes. Further, we found that wild-type plants overexpressing ORM1 are autoimmune, displaying short roots and increased ceramide levels. The autoimmunity of the ORM1 overexpression lines is dependent on SA, NHP, and bZIP60. As ORM1 is a known negative regulator of sphingolipid biosynthesis, our study uncovers a balancing role between PIs and sphingolipids in regulating immunity and ER stress responses in pi4kβ1,2.

Combined salt and low nitrate stress conditions lead to morphophysiological changes and tissue-specific transcriptome reprogramming in tomato

Despite intense research towards the understanding of abiotic stress adaptation in tomato, the physiological adjustments and transcriptome modulation induced by combined salt and low nitrate (low N) conditions remain largely unknown. Here, three traditional tomato genotypes were grown under long-term single and combined stresses throughout a complete growth cycle. Physiological, molecular, and growth measurements showed extensive morphophysiological modifications under combined stress compared to the control, and single stress conditions, resulting in the highest penalty in yield and fruit size.The mRNA sequencing performed on both roots and leaves of genotype TRPO0040 indicated that the transcriptomic signature in leaves under combined stress conditions largely overlapped that of the low N treatment, whereas root transcriptomes were highly sensitive to salt stress. Differentially expressed genes were functionally interpreted using GO and KEGG enrichment analysis, which confirmed the stress and the tissue-specific changes. We also disclosed a set of genes underlying the specific response to combined conditions, including ribosome components and nitrate transporters, in leaves, and several genes involved in transport and response to stress in roots. Altogether, our results provide a comprehensive understanding of above- and below-ground physiological and molecular responses of tomato to salt stress and low N treatment, alone or in combination.