Cell Wall Thickness Research Articles

Tunable Optical High‐Order Differential Microscopy for Cell Structure Detection

AbstractOptical differential microscopy is an important tool for the detection and recognition of transparent biological objects. Among it, the first‐order optical differentiation is commonly utilized to aid in fast, label‐free, and contactless detection. However, the characterization of detailed contours for some smooth object areas may be limited, and a higher order operation needs to be executed. A tunable optical high‐order differential microscopy is proposed and implemented, in virtue of electric‐driven liquid crystal (LC). By electrically switching the working state of LC, the differential operation can be flexibly tuned in desired order, such as from zero‐order to first‐order and second‐order differentiations. Using this scheme, clear edge‐enhanced images of different‐contrast objects even transparent biological cells are experimentally acquired under multi‐wavelength cases. Specifically, based on the connection between high‐order differential results and edge features, further gained in‐depth information in the size of light spot and structure of plant cells. The beam waist radius of a laser is determined as 0.35 ± 0.002 mm, and the cell wall thickness is estimated about 3 to 5 microns. These results may open the avenue for biological imaging and microscopic measurement.

Baseline sensitivity and physiological characteristics of natural product hinokitiol against Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum, a pathogenic fungus of oilseed rape, poses a severe threat to the oilseed rapeseed industry. In this study, we evaluated the potential of the natural compound hinokitiol against S. sclerotiorum by determining its biological activity and physiological characteristics. Our results showed that hinokitiol strongly inhibited the hyphae expansion of S. sclerotiorum, and its effective concentration of hyphae growing inhibition by 50% (EC50) against 103 S. sclerotiorum strains varied from 0.36 to 3.45 μg/mL, with an average of 1.23 μg/mL. Hinokitiol possessed better protective efficacy than therapeutic effects, and it exhibited no cross-resistance between carbendazim. After treatment with hinokitiol, many vesicular protrusions developed on the mycelium with rough surface and thickened cell wall. Moreover, the cell membrane permeability and glycerol content increased, while the oxalic acid declined after hinokitiol treatment. In addition, hinokitiol induced membrane lipid peroxidation and improved the production of reactive oxygen species (ROS) in S. sclerotiorum. Importantly, real-time quantitative polymerase chain reaction showed that cell wall and ROS synthesis-related genes were significantly up-regulated after hinokitiol treatment. This study revealed that hinokitiol has good biological activity against S. sclerotiorum and could be considered as an alternative bio-fungicide for the resistance management in controlling sclerotinia stem rot infected by S. sclerotiorum. These investigations provided new insights into understanding the toxic action of hinokitiol against pathogenic fungi. © 2024 Society of Chemical Industry.

High-performance bio-based foam from agricultural waste luffa seed oil polyols

The present study aimed to develop eco-friendly polyurethane viscoelastic foam (PVF) with enhanced tear strength while preserving softness, comfort, and safety by utilizing bio-based polyols derived from luffa seed oil (LSO). Two types of bio-based polyols (PLSO-D and PLSO-M) were synthesized through the epoxidation process using diethylene glycol (DEG) and methanol (MeOH), respectively, for the production of LSO-based polyurethane viscoelastic foams (LSO-PVFs). The analyses revealed that these polyols exhibited high dispersion, appropriate hydroxyl values, and contained by-products such as oligomeric esters of fatty acids that facilitated physical and chemical crosslinking. LSO-PVFs demonstrated a uniform and fine cell structure with abundant open-cells, thick cell walls (55.5–76.6µm), and high apparent density (48.7–50.7kg/m3). Moreover, they exhibited enhanced tensile and tear strength (increasing up to 200% compared to petroleum-based PVFs), lower water absorption, excellent mildew resistance at 10% PLSO substitution. Additionally, these factors endowed LSO-PVFs with low indentation hardness and good bottom support performance, characterized by a compressive deflection coefficient of 2.30–3.54. This approach presents a sustainable alternative for foam production that offers comfort, durability while promoting the value-added utilization of agricultural waste.

Histochemical and gene expression changes in Cannabis sativa hypocotyls exposed to increasing concentrations of cadmium and zinc

Hemp (Cannabis sativa L.) is a versatile crop that produces cellulosic bast fibres used in textiles and biocomposites. Is also finds use in phytoremediation, being a good candidate for the cultivation on marginal lands, such as those contaminated by heavy metals (HMs). HMs like cadmium (Cd) and zinc (Zn) are known to affect plant growth and impair the biosynthesis of cellulose and lignin at the cell wall level. Since cellulose is the major component in the gelatinous layer of bast fibres, HMs can impact the structure of hemp fibres and, consequently, their mechanical properties. This study investigates how varying concentrations of Cd and Zn in the soil affect the bast fibres of hemp plantlets. The chosen model is the hypocotyl, as it is ideal for studying bast fibre development: it exhibits a temporal separation between the elongation and thickening phases within a short period of approximately three weeks. C. sativa plantlets were grown for 20 days, and the hypocotyls sampled to perform histochemical observations, gene expression analysis, as well as to quantify biomass yield and Cd/Zn accumulation. Hemp plantlets grown in soils with the three highest Zn concentrations were smaller than the control group, whereas no decrease in size was observed under elevated Cd concentrations. However, at the highest Cd concentration, the root system exhibited enhanced development, accompanied by a significant increase in dry weight across all the concentrations tested. The quantification of Cd and Zn showed that the roots were the main organs accumulating HMs. Cd at the two highest concentrations decreased significantly the lumen area of bast fibres and increased their cell wall thickness. Zn decreased significantly the lumen area, but it did not impact the thickness of the cell wall at the highest concentration. Cd also increased the number of secondary fibres. Immunohistochemistry highlighted a different pattern of crystalline cellulose distribution with a signal that was less homogeneous in the presence of Cd and Zn. Gene expression analysis revealed changes in transcripts encoding cellulose synthases, fasciclin-like arabinogalactan proteins, class III peroxidases. The results obtained shed light on the molecular response and bast fibre histological changes occurring in young hemp plants exposed to Cd and Zn.

Multi-omics analysis of Nicotiana tabacum unveils tissue-specific regulatory expression strategies for cadmium accumulation

Cadmium accumulation in agricultural and industrial soils necessitates the exploration of effective phytoremediation strategies. Tobacco (Nicotiana tabacum L.), a high-biomass cash crop, exhibits remarkable capacity of cadmium accumulation. However, the underlying molecular mechanisms remain poorly understood. This study employed integrated transcriptome and proteome analyses to investigate gene and protein expression profiles in tobacco shoots and roots under short-term Cd exposure. Our results showed that root cells upregulated cell wall synthesis proteins, leading to cell wall thickening and restricting cadmium transporter proteins, thereby isolating cadmium ions in the apoplast. Conversely, shoot cells exhibit a significant increase in vacuolar transporter expression, facilitating cadmium compartmentalization and mitigating cadmium toxicity. These findings highlight the tissue-synergistic accumulation strategies employed by tobacco, revealing a different molecular regulatory mechanism for cadmium accumulation at the tissue level.

Effect of Chlormequat Chloride on the Growth and Development of Panax ginseng Seedlings

Ginseng is widely used in traditional herbal formulations in Korea, Japan, China, and Western countries. High-quality seedlings are the key to ginseng with high quality and high yield. Although tray seeding can yield large quantities of ginseng seedlings, issues such as dense planting and inadequate ventilation may result in excessive stem elongation. This elongation can lead to slender stems unable to support the weight of the leaves, resulting in seedling lodging. To inhibit the overgrowth of aboveground parts of ginseng seedlings, chlormequat chloride (CCC) was selected for foliar spraying at 0, 100, 200, and 300 mg·L−1 to study the effects of plant growth regulators on the growth and development of ginseng seedlings. When the leaves of ginseng seedlings are fully expanded, we sprayed once with 200 mg·L−1 of CCC. After 28 days, index measurements indicated that the height of ginseng seedlings decreased by 17.4%, stem thickness increased by 7.4%, leaf area decreased by 4.5%, root length increased by 6.2%, root-to-crown ratio increased by 29.8%, chlorophyll a content increased by 10.3%, chlorophyll b content increased by 12.6%, the actual chlorophyll fluorescence parameters of photosystem II under light quantum yield increased by 50.9%, electron transfer rate increased by 52.8%, photochemical quenching increased by 21.7%, nonphotochemical quenching decreased by 31.4%, antioxidant enzyme superoxide dismutase activity increased by 12.2%, catalase activity increased by 17.0%, peroxidase activity increased by 38.7%, and malondialdehyde content decreased by 18.1%. The number of intracellular starch grains increased significantly, the number of stromal lamellae in chloroplasts increased, the arrangement was more compact, and the cell wall thickness increased significantly. In conclusion, it is recommended to apply 200 mg·L−1 CCC as a foliar spray during production to inhibit seedling growth and enhance plant resistance to stem collapse and stress.

Melatonin maintains the quality and cell wall structure of plum fruits under low temperature storage

To enhance the quality of plum fruits under low temperature storage, the impact of melatonin (MT) treatment (100 μmol L−1) on the quality and cell wall structure of plum fruits under low temperature storage (at 4 °C for 28 days) was examined. The results showed that the contents of total soluble solids, total sugar, titratable acid, and vitamin C in plum fruits treated with MT were higher than control under low temperature storage, and MT helped to prevent pulp browning and maintained the overall quality of the fruits. In addition, MT inhibited the conversion of ion-binding pectin and covalently-bound pectin of plum fruits into water-soluble pectin under low temperature storage. It also decreased the activities of pectin methylesterase, polygalacturonase, β-galactosidase, and endo-β-1, 4-glucanase, while increasing the activities of xyloglucan endotransglycosylase/hydrolase and α-l-arabinofuranosidase. Correlation analysis showed that the fruit hardness and pulp hardness were positively correlated with the covalently-bound pectin content, hemicellulose content, and cellulose content, and negatively correlated with the water-soluble pectin content, ion-binding pectin content, pectin methylesterase activity, β-galactosidase activity, and endo-β-1, 4-glucanase activity. Moreover, the cell structure of plum fruits treated with MT remained more intact and tightly arranged under low temperature storage, with slower degradation of the middle lamella and higher cell wall thickness. This was beneficial for maintaining the integrity of the cell wall structure and inhibiting the increase of intercellular spaces. In conclusion, MT can maintain the quality and cell wall structure of plum fruits, inhibit cell wall degradation, and slow down the decrease in fruit hardness under low temperature storage.

The transcription factor GhMYB4 represses lipid transfer and sucrose transporter genes and inhibits fiber cell elongation in cotton.

Cotton (Gossypium hirsutum) fiber is a highly elongated single cell with a thickened cell wall. MYB transcription factors are important regulators of plant cell elongation; however, the molecular mechanism involved in regulating fiber elongation remains to be explored. Here, we present evidence that the R2R3-MYB transcription factor GhMYB4 negatively regulates cotton fiber cell elongation by suppressing the expression of two crucial genes previously reported to affect fiber development: lipid transfer protein 4 (GhLTP4) and sucrose transporter 12 (GhSWEET12). GhMYB4 is preferentially expressed in elongating fiber cells. Knockdown of GhMYB4 in cotton results in longer fiber cells, whereas overexpression of GhMYB4 in Arabidopsis leads to reduced plant height and root length. Transcriptomic and lipidomic analyses revealed that GhMYB4 is involved in coordinating three interconnected biological processes, namely lipid content regulation, auxin signaling, and sugar metabolism. Additionally, we showed that GhMYB4 inhibits the expression of GhLTP4 and GhSWEET12 by binding to the MYB cis-element (TTTAGTG) in their respective promoters. Interestingly, bHLH transcription factor 105 (GhbHLH105) and MYB transcription factor 212 (GhMYB212) counteract the inhibitory effects of GhMYB4 on the expression of GhLTP4 and GhSWEET12, respectively. These findings provide insights into the complex molecular mechanisms regulating plant cell elongation.

Isolation and characterization of Methanosphaera sp. ISO3-F5, a member of a novel and widespread species of rumen methanogens growing with methanol plus hydrogen

Rumen methanogens predominantly fall into two physiological groups: hydrogenotrophs which use hydrogen (H2) to reduce carbon dioxide (CO2) to methane (CH4), and methylotrophs which use H2 to reduce methanol and methylamines as substrates for methanogenesis. We used a dilution to extinction approach to isolate two hydrogenotrophic Methanocatella spp. and four cultures of methylotrophic methanogens from sheep rumen contents. Three of the methylotrophs were stable mixed cultures containing methanogens belonging to different lineages of the order Methanomassiliicoccales and one was a pure Methanosphaera culture. Methanosphaera sp. ISO3-F5 has a comparatively large genome (2.68 Mb) comprised of two replicons, a chromosome and a megaplasmid. The genome has an average G + C content of 30.5 % and encodes 2360 putative protein-coding genes. Cells of ISO3-F5 have a spherical shape, 0.6–1.2 µm in diameter, usually occurring in pairs or loose clumps, and have no flagellum. Cells stain Gram positive, have a single thick cell wall and divide by the formation of a cross wall. The optimum temperature for growth was 39°C to 42°C and the optimum pH was 6.7–6.8. Acetate was required for growth, but CH4 was not produced from acetate, formate, ethanol, methylamine, or isopropanol with or without H2/CO2. Volatile fatty acids and rumen fluid were also found to enhance the growth of ISO3-F5, while coenzyme M did not. ISO3-F5 produced CH4 from methanol in the presence of H2 and the genes encoding the necessary methanogenesis pathway have been identified. Based on morphological, physiological, and genomic characteristics, ISO3-F5 is a new species of the genus Methanosphaera. Our study shows that simple isolation methods allowed us to culture diverse and significant members of the rumen methanogen community.

Physiological function of hydrophobin Hydph16 in cell wall formation in agaricomycete Pleurotus ostreatus

Hydrophobins are small-secreted proteins with both hydrophobic and hydrophilic regions, enabling the mycelium to break through the air-medium interface by reducing the medium surface tension. Over 20 putative hydrophobin-encoding genes have been predicted in the agaricomycete Pleurotus ostreatus. Three hydrophobin-encoding genes, vmh2, vmh3, and hydph16, were predominantly expressed in the vegetative mycelium. Despite these common properties, we have previously demonstrated the distinct functions of Vmh2 and Vmh3 in environmental stress resistance. In this study, we focused on hydph16 and found that Δhydph16 strains had sparser aerial mycelium than control strains. The cell wall thickness of Δhydph16 strains reduced by 40 % compared to that of control strains, but no significant differences were found in the relative chitin and glucan percentages or relative putative cell wall synthesis-related gene expression levels. Furthermore, unlike vmh2 and vmh3, hydph16 deletion did not change the hydrophobicity of the aerial mycelium. This study is the first to report that the lack of hydrophobin can lead to a significant change in aerial hyphae cell wall formation without altering the major cell wall polysaccharide composition. Additionally, this study revealed multiple roles for Hydph16, distinct from those of other highly expressed hydrophobins, Vmh2 and Vmh3. These results suggested that agaricomycetes, including P. ostreatus, have evolved to possess multiple hydrophobins with different functions.

Dynamic changes of heterogeneous cell wall macromolecules in differentiating conifer xylem using cytochemical localization

Tracing dynamic changes of heterogeneous cell wall components during xylem differentiation is essential for understanding the intricate architecture of wood cell walls at the individual secondary cell wall layer level. Here we employ histochemical- and immunological approaches to visualize the deposition of cellular polymers during xylem differentiation in Pinus bungeana. In axial tracheids, deposition of crystalline cellulose and glucomannan preceded xylan and lignin. Lignification was initiated in primary cell wall corners during development of the S1 layer and intensified with cell wall thickening. Immunofluorescence labeling showed an earlier deposition of glucomannan than xylan with strong presence in S1 layer corner regions at early stages of differentiation. Quantification of immunogold-labeled xylan and glucomannan showed distinct increasing trends during thickening of tracheid wall layers with xylan labeling of the S1 and S2 layers at the S3 stage greater than the S2 stage. Differential cell wall polymer deposition was evident in mature tracheid areas with glucomannan absent in warty layers. Pectins were highly concentrated in unlignified primary cell walls but decreased with axial tracheid wall differentiation. The sequence of polymer deposition in ray cells was similar but lagged behind axial tracheids with ray parenchyma remaining unlignified with thinner cell walls than ray tracheids.

CCT39-COMT1/BGLU18-2 module promotes lignin biosynthesis in poplar

Lignin is a crucial constituent of cell walls and plays a pivotal role in plant growth and development. However, the transcriptional regulatory network governing lignin biosynthesis is not fully understood. In this study, we observed that PpnCCT39 overexpression resulted in greener stems, larger basal diameters, and increased stem dry weight. Additionally, the secondary xylem of lines overexpressing PpnCCT39 was wider, had larger xylem fiber cell areas, and thicker cell walls, compared to those of wild-type plants. Furthermore, PpnCCT39 overexpression led to elevated lignin content and enhanced the rigidity of secondary cell walls. RNA-seq and ChIP-seq association analyses identified 826 potential regulatory target genes of PpnCCT39 that were upregulated and expressed in 1-month-old PpnCCT39 overexpression lines. Gene enrichment analyses revealed enrichment in pathways related to cell wall formation, xylem and phloem development, and the phenylpropanoid pathway. Two genes involved in lignin biosynthesis, PagCOMT1 and PagBGLU18–2, exhibited significantly increased expression in stems of lines overexpressing PpnCCT39, as demonstrated by high FPKM values and RT-qPCR results. Further investigations using yeast one-hybrid, dual-luciferase assays, and electrophoretic mobility shift assays demonstrated that PpnCCT39 directly activates the transcription of PagCOMT1 and PagBGLU18–2, thereby promoting lignin biosynthesis. This study elucidated the transcriptional regulatory mechanism of PpnCCT39 in poplars and revealed its role in activating the expression of key lignin biosynthesis genes. PpnCCT39 facilitates lignin biosynthesis and secondary growth processes, offering a novel theoretical framework for modulating lignin biosynthesis and enhancing timber yield through molecular design.

Terahertz Imaging Detects Oral Cariogenic Microbial Domains Characteristics.

Dental caries, associated with plaque biofilm, is highly prevalent and significantly burdens public health. Streptococcus mutans is the main cariogenic bacteria that adheres to the tooth surface and forms an abundant extracellular polysaccharide matrix (EPS) as a cariogenic biofilm scaffold. S. mutans RNase III-encoding gene (rnc) and a putative chromosome segregation protein-encoding gene (smc) are potentially associated with EPS production. In addition, complex interactions between S. mutans and other oral microorganisms synergistically or antagonistically affect the cariogenicity. Commensal streptococci suppress the growth of cariogenic pathogens, whereas Candida albicans mediates the formation of cariogenic biofilm through aggregation and dual-species biofilm formation with S. mutans. However, label-free detection of cariogenic microbial interactions with the EPS matrix is still challenging during laboratory investigations. Herein, we hypothesized that the S. mutans rnc-smc operon affects EPS production and aimed to observe streptococci, S. mutans, and S. mutans-C. albicans using terahertz scanning near-field optical microscopy (THz s-SNOM). The light in the 0.1- to 0.3-THz frequency range interacted with the sample through a nano-probe tip by a point-by-point scanning process. Additional noise reduction of the original image was achieved by a dual kernel Gaussian filter. The monospecies of streptococci, S. mutans smc/rnc mutants, and the dual-species of S. mutans-C. albicans were scanned by THz s-SNOM. This technique provided terahertz near-field scanning images of S. mutans smc/rnc mutants, streptococci, and dual-species of S. mutans-C. albicans. Additional analysis of the original images potentially revealed the structures of the strains, such as cell diameters and cell wall thickness. In conclusion, the results suggested that the S. mutans rnc-smc operon regulates EPS production. Furthermore, this novel label-free detection of a THz near-field scanning technique had the potential to observe the morphologies of bacterial cells and EPS matrix.

Constitutive expression of cucumber CsACS2 in Arabidopsis Thaliana disrupts anther dehiscence through ethylene signaling and DNA methylation pathways.

Constitutive expression of cucumber CsACS2 in Arabidopsis disrupts anther dehiscence and male fertility via ethylene signaling and DNA methylation, revealing new avenues for enhancing crop reproductive traits. The cucumber gene CsACS2, encoding ACC (1-aminocyclopropane-1-carboxylic acid) synthase, plays a pivotal role in ethylene biosynthesis and sex determination. This study investigates the effects of constitutive CsACS2 expression in Arabidopsis thaliana on anther development and male fertility. Transgenic Arabidopsis plants overexpressing CsACS2 exhibited male sterility due to inhibited anther dehiscence, which was linked to suppressed secondary cell wall thickening. RNA-Seq analysis revealed upregulation of ethylene signaling pathway genes and downregulation of secondary cell wall biosynthesis genes, with gene set enrichment analysis indicating the involvement of DNA methylation. Rescue experiments demonstrated that silver nitrate (AgNO₃) effectively restored fertility, while 5-azacytidine (5-az) partially restored it, highlighting the roles of ethylene signaling and DNA methylation in this process. Constitutive CsACS2 expression in Arabidopsis disrupts anther development through ethylene signaling and DNA methylation pathways, providing new insights into the role of ethylene in plant reproductive development and potential applications in crop improvement.

Nanostructure-Mediated Photothermal Effect for Reinforcing Physical Killing Activity of Nanorod Arrays.

The physical killing of bacteria based on surface topography has attracted much attention due to the sustainable and safe prevention of biofilm formation. However, the antibacterial efficiency of biomedical implants derived solely from nanostructures or microstructures is insufficient to combat bacteria against common infections, such as methicillin-resistant Staphylococcus aureus with thick cell walls. Herein, photothermal therapy is carried out in the presence of nanorod arrays to mitigate infection of biomedical implants. Different from traditional photothermal therapy relying on a photosensitizer, the photothermal effect is mediated by light traps rendered by the nanorod arrays, and consequently, the photosensitizer is not needed. Finite element simulations and experiments are performed to elucidate the light-to-thermal conversion mechanism. This photothermal platform, in conjunction with thermosensitive nitric oxide therapy, is applied to treat titanium implant infection. The nanostructure-mediated photothermal effect destroys bacterial cell walls by inhibiting peptidoglycan synthesis and increasing the membrane permeability by affecting fatty acid synthesis. Furthermore, the nanorods synergistically puncture the bacterial membrane easily as demonstrated by experiments and transcriptome analysis. The results provide insights into the development of efficient antibacterial treatment of implants by combining nanostructures and photothermal therapy.

Antibiotic Resistance in Mycobacterium Tuberculosis and Non-Tuberculous Mycobacteria

Mycobacterium tuberculosis (MTB) and non-tuberculous mycobacteria (NTM) antibiotic resistance presents an important challenge to the treatment of mycobacterial infections. The therapeutic approaches are complicated by the resistance of both MTB and NTM to a variety of antibiotics. Resistance to first-line drugs such as isoniazid, rifampicin, ethambutol, and streptomycin has been consistently increasing in MTB, underscoring the necessity of effective treatment strategies. Conversely, the necessity of species-specific treatment regimens is underscored by the high resistance rates of NTM species, such as Mycobacterium avium complex, M. kansasii, and M. abscessus complex, to commonly used anti-tuberculosis pharmaceuticals. A combination of intrinsic and acquired factors are involved in the mechanisms of antibiotic resistance in these mycobacteria. Features such as biofilm formation, thick cell walls, and reduced drug uptake are responsible for intrinsic resistance in NTM, whereas acquired resistance can develop as a result of protracted antibiotic exposure. Understanding these resistance mechanisms is essential for the development of new therapies and the prevention of the increasing prevalence of drug resistance in mycobacterial infections. The significance of continuous surveillance, species-specific treatment protocols, and the development of novel antimicrobial agents to effectively manage mycobacterial diseases is emphasized by the prevalence of antibiotic resistance in MTB and NTM. This review article focuses on the molecular mechanisms that have resulted in the development of resistance in both MTB and NTMs, as well as the extent to which various classes of antimycobacterial drugs act.

Analysis of Cell Wall Mechanics in Fission Yeast.

The growth and shape of fungal cells, such as fission yeast, are strongly constrained by the mechanics of their cell wall (CW). The cell wall encases the plasma membrane and defines instantaneous cell shapes by opposing turgor pressure-derived stress on the cell surface. Measuring cell wall mechanical properties may thus bring key insights into the regulation of cell morphogenesis, cell growth, but also cell surface integrity and survival. The fission yeast cell wall has a thickness of a few tens to hundreds of nanometers, and bulk elasticity similar to that of rubber (tens of MPa). These mechanical properties vary locally around single cells, for instance, at the new vs. old growing ends, or birth scars, and may also largely depend on growth conditions and life cycle phases. While cell wall thickness and mechanics have been traditionally measured by complex methodologies including electron microscopy and atomic force microscopy, we here propose a method based on light microscopy to infer with medium-throughput cell wall mechanical properties, as well as turgor pressure in time and space in living cells. This analysis will enhance our appreciation of the mechanical regulation of fission yeast cell morphogenesis and may be directly transferable to the study of other fungal cells.

Pressure-tolerant survival mechanism of Schizophyllum commune 20R-7-F01 isolated from deep sediments 2 kilometers below the seafloor

In anaerobic high hydrostatic pressure (HHP) sedimentary environments below the seafloor, fungi are found to dominate the eukaryotic communities, playing crucial ecological roles. However, the specific mechanisms by which fungi adapt to anaerobic HHP environments remain unclear. In this study, we investigated Schizophyllum commune 20R-7-F01 isolated from coal-bearing sediments at a depth of 2 km below the seafloor. By assessing the cell viability, biomass, and cell wall thickness changes of strain 20-7-1 under different HHP conditions, we observed that, compared to 0.1 MPa, strain 20-7-1 exhibited slower growth rates and decreased cell viability at 15 MPa and 35 MPa, yet demonstrated significant pressure tolerance. Transcriptomic and metabolomic analyses revealed that this strain activated the carbohydrate metabolic process to simultaneously utilize ethanol and lactic acid fermentation pathway. Additionally, it activates the oxidoreductase activity and hydrolase activity pathways to detoxify intracellular reactive oxygen species (ROS). Activation of the metal ion binding pathway increases the proportion of unsaturated fatty acids in the cell membrane, while instigation of the integral component of membrane pathway maintains cell wall structural stability. Furthermore, activation of the DNA repair pathway repairs DNA damage, demonstrating its comprehensive adaptive mechanisms against the HHP stress. These research findings deepen our understanding of fungal survival strategies and adaptation mechanisms in extreme environments, laying the groundwork for further exploration of their roles in cycling of carbon, nitrogen, sulfur, and other elements in the deep biosphere.

Integrative DNA methylome and transcriptome analysis illuminate leaf phenotype alterations in tetraploid citrus

Whole-genome duplication (WGD) in plants triggers profound morphological and physiological changes, with DNA modification being a key epigenetic factor that helps neo-polyploids overcome challenges and gain adaptive advantages. Tetraploids were previously mined from diploid citrus seedlings, showing enhanced environmental adaptability and potential as rootstocks. These tetraploids exhibited increased leaf and cell wall thickness compared to their diploid counterparts. To explore the impact of WGD, transcriptomic and whole-genome bisulfite sequencing (WGBS) were conducted on two pairs of citrus tetraploids and their diploid controls, revealing significant molecular changes. Notably, tetraploid citrus displayed lower CG methylation levels in gene and transposable element (TE) bodies relative to diploids. Differentially methylated genes (DMGs) between tetraploids and diploids were primarily associated with immune stress, organ development, metabolic pathways, and secondary metabolism. In Trifoliate orange (Poncirus trifoliata L. Raf.) and Ziyang Xiangcheng (Citrus junos Sieb. ex Tanaka), only 150 and 58 differentially expressed genes (DEGs) were identified, respectively, with enrichment in critical cellular processes such as cell wall synthesis, plastid development, and pathways modulating chloroplasts and plasma membranes. A total of 70 genes showed both differential methylation and expression, including ACN1, Nac036, and ASMT1, which are involved in stomatal development, leaf morphology, and melatonin synthesis, respectively, offering insight into the regulatory mechanisms of phenotype alterations after polyploidization. These findings reveal the epigenetic modifications in polyploid citrus and highlight the role of polyploidization-induced methylation in driving phenotypic changes.

Identification and characterization of a novel Haematococcus pluvialis strain resistant to Paraphysoderma sedebokerense infection

The commercial culture of Haematococcus pluvialis is threatened by the pathogen Paraphysoderma sedebokerense, leading to substantial losses in the natural astaxanthin industry. This study successfully identified a novel H. pluvialis strain WBG-26, which exhibited high resistance to P. sedebokerense in both laboratory and open raceway ponds. Comparative analysis showed that the resistant strain WBG-26 had a thicker cell wall and lower levels of specific monosaccharides which may be closely related to resistance. RNA-sequencing analysis revealed differential gene expression profiles, with 29 up-regulated and 25 down-regulated genes identified as crucial for resistance. Using bioinformatics analysis, we identified several potential resistance genes and resistance-related genes, such as those encoding receptor-like kinases, leucine-rich repeat, transcription factors, CAZymes, and heat shock proteins, which may play critical roles in defense response. This study represents a comprehensive investigation of multiple defense mechanisms of microalgae, providing insights into breeding disease-resistant microalgal strains for biotechnological applications.