Cell Wall Stability Research Articles

Exogenous silicon improved the cell wall stability by activating non-structural carbohydrates and structural carbohydrates metabolism in salt and drought stressed Glycyrrhiza uralensis stem

Exogenous silicon improved the cell wall stability by activating non-structural carbohydrates and structural carbohydrates metabolism in salt and drought stressed Glycyrrhiza uralensis stem

Comparative transcriptomic analysis reveals the role of signal transduction and cell wall stabilization in cold tolerance of ‘Chamnok’ and ‘Keumsull’ tea plants

Comparative transcriptomic analysis reveals the role of signal transduction and cell wall stabilization in cold tolerance of ‘Chamnok’ and ‘Keumsull’ tea plants

Diethyl aminoethyl hexanoate ameliorates salt tolerance associated with ion transport, osmotic adjustment, and metabolite reprograming in white clover

BackgroundSoil salinization is a serious environmental hazard, limiting plant growth and production in different agro-ecological zones worldwide. Diethyl aminoethyl hexanoate (DA-6) as an essential plant growth regulator (PGR) exhibits a beneficial role in improving crop growth and stress tolerance. However, the DA-6-regulated effect and mechanism of salt tolerance in plants are still not fully understood. The objective of current study was to disclose salt tolerance induced by DA-6 in relation to changes in water and redox balance, photosynthetic function, ionic homeostasis, and organic metabolites reprogramming in white clover (Trifolium repens).ResultsA prolonged duration of salt stress caused water loss, impaired photosynthetic function, and oxidative injury to plants. However, foliar application of DA-6 significantly improved osmotic adjustment (OA), photochemical efficiency, and cell membrane stability under salt stress. In addition, high salinity induced massive accumulation of sodium (Na), but decreased accumulation of potassium (K) in leaves and roots of all plants. DA-6-treated plants demonstrated significantly higher transcript levels of genes involved in uptake and transport of Na and K such as VP1, HKT8, SOS1, NHX2, NHX6, and SKOR in leaves as well as VP1, HKT1, HKT8, H+-ATPase, TPK5, SOS1, NHX2, and SKOR in roots. Metabolomics analysis further illustrated that DA-6 primarily induced the accumulation of glucuronic acid, hexanoic acid, linolenic acid, arachidonic acid, inosose, erythrulose, galactopyranose, talopyranose, urea, 1-monopalmitin, glycerol monostearate, campesterol, stigmasterol, and alanine.ConclusionsThe DA-6 significantly up-regulated transcript levels of multiple genes associated with increased Na+ compartmentalization in vacuoles and Na+ sequestration in roots to reduce Na+ transport to photosynthetic organs, thereby maintaining Na+ homeostasis under salt stress. The accumulation of many organic metabolites induced by the DA-6 could be attributed to enhanced cell wall and membrane structural stability and functionality, OA, antioxidant defense, and downstream signal transduction in leaves under salt stress. The present study provides a deep insight about the synergistic role of DA-6 in salt tolerance of white clover.

Influence of cell-wall permeability on starch digestion in sweet potato cells

This study aims to evaluate the effects of cell-wall permeability on starch digestibility in sweet potato (SP) cells. Intact cells were separated from purple, red, and white SP tubers, which differ in terms of cell-wall composition and structure, and used as whole SP food models. Purple SP cells exhibited markedly higher polyphenol content but lower starch crystallinity than red and white SP cells. Thermal analysis showed that the gelatinization enthalpy of starch considerably increased due to cell wall damage and the damaged cells of purple SP increased more. The purple SP cell wall dissolved the least pectin and had the lowest permeability for amylase-sized fluorescence probes after cooking, indicating it had stronger thermal stability and resistance to amylase penetration. Among the three cell samples, purple SP cells had the highest starch digestibility (93.95%) when the cell walls were damaged; however, when cell walls remained intact, the starch digestibility (75.95%) of purple SP cells was significantly lower. Therefore, cell-wall permeability mainly controls starch digestion within SP tubers. More polyphenols may enhance cell-wall stability and barrier amylase capacity. This study provides novel insights into the function of the cell wall, which protects starchy plants from the action of amylase.

Improving hawthorn fruit pulp processing and quality through optimized freeze-thaw cycles

Hawthorn fruit is firm, making it difficult to process into fruit pulp. To improve the processing suitability of hawthorn fruit pulp, one, two, and three freeze-thaw cycles (FTCs, frozen at −18 °C for 24 h, then thawed at 5 °C or 25° C for 6 h) were performed on hawthorn fruit in this study. Using unfrozen specimens as the controls, the study assessed fruit softening characteristics and rheological properties, taste traits, and nutritional components of the fruit pulp. Freeze-thaw treatments decreased fruit firmness and cell-wall stability, increased juice yield during pulp processing, and reduced the viscosity, sourness, and astringency of hawthorn fruit pulp, likely by enhancing pectin solubility. The treatment effect was influenced by both FTC number and thawing temperature. Two FTCs with a thawing temperature of 5 °C were most effective, promoting the transformation of protopectin into water-soluble pectin (WSP) to the fullest extent. The treatment reduced firmness to about 25 % of the initial value, increased juice yield by about 22 %, increased the sugar-acid ratio to 11.6, and reduced the sourness and astringency of the fruit pulp. It increased the contents of total flavones and anthocyanidins without affecting the contents of vitamin C. Therefore, the use of two FTCs with a thawing temperature of 5 °C can facilitate the preparation of hawthorn fruit pulp while preserving its nutritional properties and improving its taste profile.

Antibacterial characteristics and mechanistic insights of combined tea polyphenols, Nisin, and epsilon-polylysine against feline oral pathogens: a comprehensive transcriptomic and metabolomic analysis.

This study evaluates the antibacterial characteristics and mechanisms of combined tea polyphenols (TPs), Nisin, and ε-polylysine (PL) against Streptococcus canis, Streptococcus minor, Streptococcus mutans, and Actinomyces oris, common zoonotic pathogens in companion animals. Pathogenic strains were isolated from feline oral cavities and assessed using minimum inhibitory concentration (MIC) tests, inhibition zone assays, growth kinetics, and biofilm inhibition studies. Among single agents, PL exhibited the lowest MIC values against all four pathogens. TP showed significant resistance against S. minor, and Nisin against S. mutans. The combination treatment (Comb) of TP, Nisin, and PL in a ratio of 13:5:1 demonstrated broad-spectrum antibacterial activity, maintaining low MIC values, forming large inhibition zones, prolonging the bacterial lag phase, reducing growth rates, and inhibiting biofilm formation. RNA sequencing and metabolomic analysis indicated that TP, Nisin, and PL inhibited various membrane-bound carbohydrate-specific transferases through the phosphoenolpyruvate-dependent phosphotransferase system in S. canis, disrupting carbohydrate uptake. They also downregulated glycolysis and the citric acid cycle, inhibiting cellular energy metabolism. Additionally, they modulated the activities of peptidoglycan glycosyltransferases and d-alanyl-d-alanine carboxypeptidase, interfering with peptidoglycan cross-linking and bacterial cell wall stability. The Comb therapy significantly enhances antibacterial efficacy by targeting multiple bacterial pathways, offering potential applications in food and pharmaceutical antimicrobials.

Differential prolyl hydroxylation by six Physcomitrella prolyl-4 hydroxylases

Hydroxylation of prolines to 4-trans-hydroxyproline (Hyp) is mediated by prolyl-4 hydroxylases (P4Hs). In plants, Hyps occur in Hydroxyproline-rich glycoproteins (HRGPs), and are frequently O-glycosylated. While both modifications are important, e.g. for cell wall stability, they are undesired in plant-made pharmaceuticals. Sequence motifs for prolyl-hydroxylation were proposed but did not include data from mosses, such as Physcomitrella. We identified six moss P4Hs by phylogenetic reconstruction. Our analysis of 73 Hyps in 24 secretory proteins from multiple mass spectrometry datasets revealed that prolines near other prolines, alanine, serine, threonine and valine were preferentially hydroxylated. About 95 % of Hyps were predictable with combined established methods. In our data, AOV was the most frequent pattern. A combination of 443 AlphaFold models and MS data with 3000 prolines found Hyps mainly on protein surfaces in disordered regions. Moss-produced human erythropoietin (EPO) exhibited O-glycosylation with arabinose chains on two Hyps. This modification was significantly reduced in a p4h1 knock-out (KO) Physcomitrella mutant. Quantitative proteomics with different p4h mutants revealed specific changes in protein amounts, and a modified prolyl-hydroxylation pattern, suggesting a differential function of the Physcomitrella P4Hs. Quantitative RT-PCR revealed a differential effect of single p4h KOs on the expression of the other five p4h genes, suggesting a partial compensation of the mutation. AlphaFold-Multimer models for Physcomitrella P4H1 and its target EPO peptide superposed with the crystal structure of Chlamydomonas P4H1 suggested significant amino acids in the active centre of the enzyme and revealed differences between P4H1 and the other Physcomitrella P4Hs.

Unveiling the protective role of anthocyanin in rice: insights into drought-induced oxidative stress and metabolic regulation.

This study investigates the impact of anthocyanin treatment on rice plants under drought stress, focusing on phenotypic, molecular, and biochemical responses. Anthocyanin were treated to one month old plants one week before the droughtexposure. Drought stress was imposed by using 10% polyethylene glycol (PEG 6000). Anthocyanin-treated plants exhibited significant enhancements in various traits, including growth parameters and reproductive characteristics, under normal conditions. When subjected to drought stress, these plants displayed resilience, maintaining or improving essential morphological and physiological features compared to non-treated counterparts. Notably, anthocyanin application mitigated drought-induced oxidative stress, as evidenced by reduced levels of reactive oxygen species (ROS) and lipid membrane peroxidation. The study also elucidates the regulatory role of anthocyanins in the expression of flavonoid biosynthetic genes, leading to increased levels of key secondary metabolites. Furthermore, anthocyanin treatment influenced the levels of stress-related signaling molecules, including melatonin, proline, abscisic acid (ABA), and salicylic acid (SA), contributing to enhanced stress tolerance. The enzymatic activity of antioxidants and the expression of drought-responsive genes were modulated by anthocyanins, emphasizing their role in antioxidant defense and stress response. Additionally, anthocyanin treatment positively influenced macronutrient concentrations, particularly calcium ion (Ca+), potassium ion (K+), and sodium ion (Na+), essential for cell wall and membrane stability. The findings collectively highlight the multifaceted protective effects of anthocyanins, positioning them as potential key players in conferring resilience to drought stress in rice plants. The study provides valuable insights into the molecular and physiological mechanisms underlying anthocyanin-mediated enhancement of drought stress tolerance, suggesting promising applications in agricultural practices for sustainable crop production.

Alginate Oligosaccharides Alleviate Salt Stress in Rice Seedlings by Regulating Cell Wall Metabolism to Maintain Cell Wall Structure and Improve Lodging Resistance.

Salt stress is one of the major abiotic stresses that damage the structure and composition of cell walls. Alginate oligosaccharides (AOS) have been advocated to significantly improve plant stress tolerance. The metabolic mechanism by which AOS induces salt tolerance in rice cell walls remains unclear. Here, we report the impact of AOS foliar application on the cell wall composition of rice seedlings using the salt-tolerant rice variety FL478 and the salt-sensitive variety IR29. Data revealed that salt stress decreased biomass, stem basal width, stem breaking strength, and lodging resistance; however, it increased cell wall thickness. In leaves, exogenous AOS up-regulated the expression level of OSCESA8, increased abscisic acid (ABA) and brassinosteroids (BR) content, and increased β-galacturonic activity, polygalacturonase activity, xylanase activity, laccase activity, biomass, and cellulose content. Moreover, AOS down-regulated the expression levels of OSMYB46 and OSIRX10 and decreased cell wall hemicellulose, pectin, and lignin content to maintain cell wall stability under salt stress. In stems, AOS increased phenylalamine ammonia-lyase and tyrosine ammonia-lyase activities, while decreasing cellulase, laccase, and β-glucanase activities. Furthermore, AOS improved the biomass and stem basal width and also enhanced the cellulose, pectin, and lignin content of the stem, As a result, increased resistance to stem breakage strength and alleviated salt stress-induced damage, thus enhancing the lodging resistance. Under salt stress, AOS regulates phytohormones and modifies cellulose, hemicellulose, lignin, and pectin metabolism to maintain cell wall structure and improve stem resistance to lodging. This study aims to alleviate salt stress damage to rice cell walls, enhance resistance to lodging, and improve salt tolerance in rice by exogenous application of AOS.

Inhibitory effects and mechanisms of cinnamaldehyde against Fusarium oxysporum, a serious pathogen in potatoes.

Potatoes, a major economic crop, are significantly impacted by Fusarium dry rot, a prevalent postharvest disease. Despite the broad-spectrum antimicrobial properties of cinnamaldehyde, a naturally-derived plant substance, its efficacy against the causal pathogen of potato dry rot (Fusarium oxysporum) and the underlying mechanisms have not been extensively studied. Our study demonstrates that cinnamaldehyde effectively inhibits the growth of Fusarium oxysporum, the pathogen responsible for potato dry rot, and increases its sensitivity to environmental stress factors such as extreme temperatures and high salt stress. Treatment with cinnamaldehyde results in altered fungal mycelium morphology, compromised cell wall stability, and disrupted cell membrane integrity, thereby reducing spore viability. Specifically, it interferes with the cell membrane and cell wall structures of the fungus, potentially disrupting fungal growth by modulating signaling pathways involved in cell wall maintenance, chitin metabolism, and GPI-anchored protein function. Notably, we show that cinnamaldehyde induces a form of regulated cell death in F. oxysporum, which is characterized not as typical apoptosis, as evidenced by Annexin V negative staining. However, the specific cell death type and underlying mechanism still needed to be further explored. Cinnamaldehyde, an environmentally friendly plant-based active compound, exhibits strong inhibitory effects on F. oxysporum, indicating its potential use in the prevention and control strategies for potato dry rot. This research contributes to the understanding of novel antifungal mechanisms and offers promising insights into eco-friendly alternatives for managing this economically significant postharvest disease. © 2024 Society of Chemical Industry.

Leaf developmental patterns of two species of Baccharis (Asteraceae): an analysis based on cell wall pectins

The cell wall plays a primary role in plant growth, which is regulated by cellulose microfibrils, proteins, and pectins. Regarding pectins, the rate of homogalacturonan (HG) methylesterification and the type of rhamnogalacturonan side chains can mediate leaf development. Herein, we evaluated pectic compounds of the cell walls by immunocytochemistry during the leaf development of Baccharis dracunculifolia DC. and Baccharis platypoda DC. Leaves in different maturation stages (from leaf bud to 9th node) were collected in a rupestrian field and fixed in formalin, acetic acid for anatomical and immunocytochemical analyses using monoclonal antibodies (JIM5, JIM7, LM5, and LM6). Both species showed similar anatomical structures based on peculiar cell wall pectic matrices. Baccharis platypoda leaves reach precocious maturation in the 3rd node, while B. dracunculifolia reaches maturation in the 6th node. These results seem to be related to HGs already de-methylesterified in the leaf primordia located in the leaf bud of B. platypoda. Epitopes of (1→5) α-l-arabinan occurred only in the collenchyma of B. platypoda, supporting cell wall stability. (1→4) β-D-galactans showed different fluorescence intensities in the two species, which changed during leaf development. The different rates of leaf tissue maturation between the two Baccharis species are influenced by variations in the pectic compounds of the cell walls, especially regarding the rate of HG methylesterification.

UV-C pretreatment of wastewater-grown algal biomass for recover of biofuel precursors

In the present study, ultraviolet radiation C (UV-C) was used as a pretreatment tool for the optimal recovery of biofuel precursors from algae Chlorella vulgaris. The pretreatment efficiency of UV-C with fixed light intensity (1.173 mWcm−2) on 1.5 gL-1 algal biomass was observed at 0, 0.5, 1, 2, 5, 10, and 20 h of irradiation by measuring the released sugar content and soluble chemical oxygen demand (sCOD). The UV-C pretreated algal cells were also analyzed through impedance spectroscopy, fluorescence microscope, and digital images to assess the degree of cell wall disintegration. The released sugar content reached a maximum of 73.61 mg L-1 at 10 h of exposure, whereas the maximum sCOD of 190 mg L-1 was achieved at 20 h exposure. Image analysis indicated that the chlorophyll content declined exponentially from 7.21 to 0.14 µgmL-1 with UV-C exposure. An increase in UV-C exposure time resulted in decreased impedance and increased conductance. The SYTOX green fluorescence also increased with 10 h of exposure, followed by a decline. Therefore, the cell wall stability gets compromised and the permeability increases with increment in UV-C exposure. This triggers extensive release in cell wall sugar content with exposure. Further exposure destabilizes the cell wall leading to discreet breakage. This breakage disperses internal content to bulk liquid, causing elevated sCOD with reduced sugar content. The present study showed that UV-C to be a potential pretreatment strategy to release precursors to derive biofuels such as biohydrogen, bioethanol and others.

Assessing the modifications and degradation of cell wall polymers during the ripening process of Rubus ulmifolius Schott fruit

ABSTRACT The stability of cell walls and their constituents, extractives, and water during the development and ripening stages of Rubus ulmifolius Schott fruits (blackberry fruit) was explored. The cell wall plays a crucial role in providing structural support and protection to the fruit, maintaining its shape and integrity. It acts as a barrier against mechanical stress, pathogens, and environmental factors. The ripening stages of blackberry fruit were previously classified in four stages according to the size and volatile components in each one. In the present work, we examine the water and sugar content, thermodynamic properties of the cell wall, and colour determination in each of the four ripening stages. The results indicate that the thermal stability of the fruit decreases during ripening, attributed to depolymerisation and changes in the physicochemical properties of the cell wall polysaccharides. Furthermore, the research reveals that the fruit’s colour and sugar content undergo changes throughout its development and ripening process. These findings suggest that the stability of the cell walls in ripening fruits is influenced by their constituents and interactions, and that ripening is accompanied by alterations. This knowledge can be used to improve fruit production, storage, and marketing strategies, ultimately benefiting both producers and consumers.

A Physiogenomic Study of the Tolerance of Saccharomyces cerevisiae to Isoamyl Alcohol

Isoamyl alcohol is a clear, unpleasantly odorous, colorless liquid of higher alcohol that emits a fruity aroma when heavily diluted. It has received much attention in recent years as a new fuel with a high energy density. Isoamyl alcohol can be produced industrially by microbial fermentation. Still, its toxicity to host cells has limited its potential for industrial production, and the molecular mechanism of its toxic effects has not yet been elucidated. In this study, RNA-Seq technology was used to analyze the transcripts of Saccharomyces cerevisiae under normal conditions and in the presence of isoamyl alcohol (0.5 g/L and 2.5 g/L). The results showed that the expression of the cell wall (CCW12, BGL2, NCW2 and SUN4), cell membrane (ELO1, ERG2, FAA1, and OPI3), translation and other structural genes were significantly down-regulated. The expression of genes related to ATP biosynthesis, NADPH biosynthesis (ZWF1), and metal ion transport (PMC1) proteins were up-regulated. Strains with key genes knocked out were cultured without isoamyl alcohol. Combined results suggested that isoamyl alcohol may affect cell wall stability and cell membrane fluidity, and the expression of genes related to ion homeostasis and energy production may play a protective role against isoamyl alcohol stress. By maintaining cell wall stability/membrane fluidity under isoamyl alcohol pressure, improving certain ion homeostasis, and generating energy/NADPH, it is possible to overcome the toxicity of isoamyl alcohol in industrial fermentation processes to a certain extent.

Saccharomyces cerevisiae survival against heat stress entails a communication between CCT and cell wall integrity pathway.

The chaperonin TRiC/CCT is cytosolic cylindrical complex of 16 subunits encoded by eight essential genes CCT1-8. It contributes to folding 10% of cellular polypeptides in yeast. The strain carrying substitution point mutation G412E in the equatorial domain of Cct7p resulted in the improper folding of substrates. In this study, the Cct7p mutant exhibited sensitivity to non-optimal growth temperatures and cell wall stressors. Heat shock is known to disrupt cell wall and protein stability in budding yeast. Mitogen-activated protein kinase-mediated cell wall integrity pathway gets activated to compensate the perturbed cell wall. Overexpression of the PKC1 and SLT2 genes of MAPK signaling pathway in mutant rescued the growth and cell division defects. Additionally, the genes of the CWI pathway such as SED1, GFA1, PIR1, and RIM21 are down-regulated. The Cct7p mutant strain (G412E) is unable to withstand the heat stress due to the underlying defects in protein folding and cell wall maintenance. Taken together, our results strongly indicate the interaction between CCT and cell wall integrity pathway.

Optimization of postharvest progesterone treatment to alleviate chilling injury in mango fruit, maintaining intracellular energy, cell wall stability, and antioxidant activity

Mango is a tropical fruit that is highly susceptible to chilling injury (CI) when stored at low temperatures, resulting in reduced quality and shelf life. In this study, we investigated the potential of progesterone (PROG) treatment concentration and duration to reduce CI in mango during storage under low-temperature conditions and optimised the treatment using response surface methodology (RSM). The study was conducted over two consecutive seasons. The first trial was conducted using different submergence concentrations and periods (0, 1, 5, 10, 15, or 20 µM for 5, 10, 15, 20, or 30 min), the experimental data were analyzed using RSM to optimize and determine the optimal concentration and timing of treatment based on several measurements, including CI index, firmness, malondialdehyde, and electrolyte leakage. Based on this, the optimal conditions for PROG treatment were used, which were at a concentration of 12 µM for 15 min, and their different effects on fruit quality were studied in comparison to the control in the following season. We evaluated the effects of progesterone treatment on fruit quality parameters during storage at 6 ± 1 °C for up to four weeks, depending on CI, fruit firmness, electrolyte leakage, malondialdehyde content, total phenolic content, 2,2-diphenyl-1-picrylhydrazyl, trolox equivalent antioxidant capacity, PROG residue in mango mesocarp, proline, superoxide dismutase, catalase, glutathione reductase activity, lipoxygenase, assay of pectin-modifying enzymes activity (polygalacturonase, β-galactosidase, and pectin methylesterase), ATP, and ATPase activity. We also conducted a principal component analysis between these indicators. Our results indicate that progesterone treatment significantly reduced the incidence and severity of CI in mangoes, with the highest effect observed at a concentration of 12 µM. Under these conditions, mangoes exhibited lower CI, electrolyte leakage, malondialdehyde content, and lipoxygenase activity, in addition to higher firmness, and antioxidant activity, compared to the control samples. Overall, our findings demonstrate that progesterone treatment can effectively reduce CI and improve the quality and shelf life of mangoes during storage under low-temperature conditions.

Osmotic Stress Responses, Cell Wall Integrity, and Conidiation Are Regulated by a Histidine Kinase Sensor in Trichoderma atroviride.

Trichoderma atroviride responds to various environmental stressors through the mitogen-activated protein kinase (MAPK) Tmk3 and MAPK-kinase Pbs2 signaling pathways. In fungi, orthologues to Tmk3 are regulated by a histidine kinase (HK) sensor. However, the role of T. atroviride HKs remains unknown. In this regard, the function of the T. atroviride HK Nik1 was analyzed in response to stressors regulated by Tmk3. The growth of the Δnik1 mutant strains was compromised under hyperosmotic stress; mycelia were less resistant to lysing enzymes than the WT strain, while conidia of Δnik1 were more sensitive to Congo red; however, ∆pbs2 and ∆tmk3 strains showed a more drastic defect in cell wall stability. Light-regulated blu1 and grg2 gene expression was induced upon an osmotic shock through Pbs2-Tmk3 but was independent of Nik1. The encoding chitin synthases chs1 and chs2 genes were downregulated after an osmotic shock in the WT, but chs1 and chs3 expression were enhanced in ∆nik1, ∆pbs2, and ∆tmk3. The vegetative growth and conidiation by light decreased in ∆nik1, although Nik1 was unrequired to activate the light-responsive genes by Tmk3. Altogether, Nik1 regulates responses related to the Pbs2-Tmk3 pathway and suggests the participation of additional HKs to respond to stress.

Integrated miRNA and mRNA Transcriptome Analysis Reveals Eggplant’s (Solanum melongena L.) Responses to Waterlogging Stress

Waterlogging stress poses a significant threat to eggplants (Solanum melongena L.), causing root oxygen deficiency and subsequent plant damage. This study aims to explore the morphological changes and chlorophyll and lignin indicators of eggplant seedlings under different time points (0, 3, 6, 12, 24, 48 h) of waterlogging stress. High-throughput sequencing was used to identify differentially expressed miRNAs and mRNAs in response to waterlogging stress in eggplants. The results showed that the content of chlorophyll a significantly decreased during the early stage of waterlogging stress, while the degradation of chlorophyll b intensified with prolonged stress, and carotenoid content remained relatively stable. Additionally, this study investigated changes in root lignin, indicating its role in enhancing cell wall stability and tolerance to cope with hypoxic stress. Using DESeq2, 246 differentially expressed miRNAs were identified, among which significant changes were observed in the miR156, miR166, miR167, and miR399 families. These miRNAs may play a crucial regulatory role in eggplant’s adaptation to the hypoxic environment after waterlogging stress. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that differentially expressed genes were mainly related to cellular physiological processes, metabolic processes, and the biosynthesis of secondary metabolites, influencing the seedlings’ stress resistance under different waterlogging conditions. Furthermore, by constructing a regulatory miRNA–target gene network that pertains to eggplant’s response to waterlogging stress, we have laid the foundation for revealing the molecular mechanisms of eggplant’s response to waterlogging stress.

Integrated analysis of transcriptome, metabolome and physiology revealed the molecular mechanisms for elevated pH-mediated-mitigation of aluminum-toxicity in Citrus sinensis leaves

The contribution of aluminum (Al)-pH-interaction-responsive metabolites and genes to Al-tolerance in Citrus leaves is still poorly understood. Seedlings of ‘Xuegan’ (Citrus sinensis) were supplied with nutrient solution at a pH of 4.0 or 3.0 and an Al concentration of 1 or 0 mM for 18 weeks. Thereafter, we investigated the impacts of Al-pH interactions on plant growth; Al concentrations in leaves and roots; and metabolome, transcriptome, and related physiological indices in leaves. Elevated pH ameliorated Al-toxicity-induced reduction of seedling (leaf) growth. Here, we screened 867 upregulated and 1041 downregulated genes, and 43 [eight primary metabolites (PMs) + 35 secondary metabolites (SMs)] and 28 downregulated (23 PMs + five SMs) in pH 3.0 + 1 mM Al-treated leaves (P3AL) vs. pH 3.0 + 0 mM Al-treated leaves (P3L); and 410 upregulated and 149 downregulated genes, and 75 upregulated (20 PMs + 55 SMs) and 32 downregulated (25 PMs + seven SMs) metabolites in pH 4.0 + 1 mM Al-treated leaves (P4AL) vs. pH 4.0 + 0 mM Al-treated leaves (P4L), implying that elevated pH ameliorated Al-toxic impacts on gene expression, but it enhanced the adaptability of metabolites to Al-stress. Further analysis suggested that raised pH-mediated-amelioration of leaf Al-stress involved the several aspects, including: (a) decreased accumulation of callose and low methylesterified pectin, increased accumulation of high methylesterified pectin, and enhanced cell wall stability; (b) less alterations of lipid metabolism and downregulation of PMs; (c) increased biosynthesis and accumulation of SMs; and (d) enhanced ability to maintain energy, phosphate and cell redox homeostasis, and less oxidative injury due to higher ability to maintain the balance between reactive oxygen species and aldehyde generation and detoxification. Some metabolic pathways such as glycolysis / gluconeogenesis and phenylpropanoid pathway; metabolites such as callose and phenolic compounds; and genes such as xyloglucan endotransglucosylase/hydrolases, purple acid phosphatases, phytochelatin synthase 3, and cysteine synthase, might involve in raised pH-induced amelioration of leaf Al-stress. Also, some similarities and differences existed between leaves and roots in Al-pH-interaction-responsive metabolites and genes.

Rhizobacteria-enhanced drought tolerance and post-drought recovery of creeping bentgrass involving differential modulation of leaf and root metabolism.

Rhizobacteria that produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCd) that inhibits ethylene production may mitigate stress damages. The objectives of this study were to examine whether a novel strain of ACCd-producing bacteria, Paraburkholderia aspalathi "WSF23," promotes plant tolerance to drought stress and post-stress recovery and determine changes in metabolic profiles in leaves and roots associated with the positive ACCd-bacteria effects in cool-season perennial grass species. Creeping bentgrass (Agrostis Stolonifera L. cv. "Penncross") plants were inoculated with P. aspalathi "WSF23" and exposed to drought by withholding irrigation for 35 days, followed by re-watering for 15 days in growth chambers. Inoculated plants demonstrated increased turf quality, canopy density, and root growth during drought stress and more rapid re-growth upon re-watering. Metabolomic analysis demonstrated that inoculation with P. aspalathi "WSF 23" increased the content of metabolites in the metabolic pathways related to stress defense, including osmoregulation, cell wall stability, and antioxidant protection in both leaves and roots, as well as nitrogen metabolism in roots of creeping bentgrass exposed to drought stress. The promotion of post-stress recovery by P. aspalathi "WSF 23" was mainly associated with enhanced carbohydrate and pyrimidine metabolism and zeatin biosynthesis pathways in leaves and increased carbohydrates, biosynthesis of DNA and proteins, cellular metabolism, and TCA cycle activity in roots. These results provide insights into the metabolic pathways regulated by "WSF23," with the PGPR conferring improvements in drought stress tolerance and post-drought recovery in a perennial grass species.