Plant cell walls

Cell wall bricks of defence: the case study of oligogalacturonides

The plant cell wall (CW) is more than a structural barrier; it serves as the first line of defence against pathogens and environmental stresses. During pathogen attacks or physical damage, fragments of the CW, known as CW-derived Damage-Associated Molecular Patterns (CW-DAMPs), are released. These molecular signals play a critical role in activating the plant's immune responses. Among CW-DAMPs, oligogalacturonides (OGs), fragments derived from the breakdown of pectin, are some of the most well-studied. This review highlights recent advances in understanding the functional and signalling roles of OGs, beginning with their formation through enzymatic CW degradation during pathogen invasion or mechanical injury. We discuss how OGs perception triggers intracellular signalling pathways that enhance plant defence and regulate interactions with microbes. Given that excessive OG levels can negatively impact growth and development, we also examine the regulatory mechanisms plants use to fine-tune their responses, avoiding immune overactivation or hyper- immunity. As natural immune modulators, OGs (and more generally CW-DAMPs), offer a promising, sustainable alternative to chemical pesticides by enhancing crop resilience without harming the environment. By strengthening plant defences and supporting eco-friendly agricultural practices, OGs hold great potential for advancing resilient and sustainable farming systems.

Potential of Bio-Sourced Oligogalacturonides in Crop Protection

During plant development or interactions with pathogens, modifications of the plant cell wall occur. Among the enzymes involved, pectinases, particularly polygalacturonases (PGases), play a crucial role in the controlled hydrolysis of cell wall polysaccharides, leading to the formation of oligogalacturonides (OGs). These pectin-derived fragments act as key elicitors of plant defense responses, stimulating innate immunity and enhancing resistance to pathogens by modulating the expression of genes involved in immune responses and inducing the production of defense compounds. OGs are of particular interest for plant protection as a natural alternative to conventional phytosanitary products as they can be obtained through chemical, thermal, or enzymatic degradation of plant biomass. In a sustainable approach, agricultural by-products rich in pectin, such as citrus peels, apple pomace, or sugar beet pulp, offer an eco-friendly and cost-effective alternative for OG production. Thus, the current review aims to (i) update the state of the art about the different methods used to produce OGs, (ii) explore the potential of OGs as bio-based biocontrol molecules, and (iii) examine the relevance of new pectin sources for OG production.

Cell wall dynamic changes and signaling during plant lateral root development

Lateral roots (LRs), are an important component of plant roots, playing a crucial role in anchoring the plant in the soil and facilitating the uptake of water and nutrients. As post-embryonic organs, LRs originate from the pericycle cells of the primary root, and their formation is characterized by precise regulation of cell division and complex intercellular interactions, both of which are closely tied to cell wall regulation. Considering the rapid advances in molecular techniques over the past three decades, we reframe the understanding of the dynamic change in cell wall during LR development by summarizing the factors that precipitate these changes and their effects, as well as the regulated signals involved. Additionally, we discuss current challenges in this field and propose potential solutions.

Xylan structural diversity, biosynthesis, and functional regulation in plants

Xylan is a vital component of plant cell walls, contributing to their structural integrity and flexibility through interactions with other polymers. Its structure varies among plant species, influencing the mechanical properties of cell walls. Xylan also has significant industrial potential, including in biofuels, biomaterials, food, and pharmaceuticals, due to its ability to be converted into valuable bioproducts. However, key aspects of xylan biosynthesis, regulation, and structural impact on plant growth and structures remain unclear. This review highlights current researches on xylan biosynthesis, modification, and applications, identifying critical gaps in knowledge. Meanwhile the review proposes new approaches to regulate xylan synthesis and understand its role in cell wall assembly and interactions with other polymers. Addressing these gaps could unlock the full industrial potential of xylan, leading to more sustainable applications.

Effects of Silicon Concentration and Synthesis Duration on Lignin Structure: A Spectroscopic and Microscopic Study

Silicon (Si) is a highly abundant mineral in Earth's crust. It plays a vital role in plant growth, providing mechanical support, enhancing grain yield, facilitating mineral nutrition, and aiding stress response mechanisms. The intricate relationship between silicification and lignin chemistry significantly impacts cell wall structure. Yet, the precise influence of Si on lignin synthesis remains elusive. This study investigated the interaction between Si and lignin model compounds during in vitro synthesis. Employing spectroscopic and microscopic analyses, we delineated how Si concentrations modulate lignin polymerization dynamics, particularly affecting molecular conformation and aggregation behavior over time. Fluctuations in the polymer structure are directly related to both the synthesis time and the concentration of silica. Our results demonstrate that lower Si concentrations promote the aggregation of lignin oligomers into larger particles, while higher concentrations increase the possibility of oligomer repulsion, thus preventing particle growth. These findings elucidate the intricate interplay between Si and lignin, which is crucial for understanding plant cell wall structure and stress resilience. Moreover, the results provide insights for developing lignin-silica materials with increasing applications in industry and medicine.

Revisiting the emerging pathosystem of rice sheath blight: deciphering the Rhizoctonia solani virulence, host range, and rice genotype-based resistance

Sheath blight, caused by Rhizoctonia solani AG1 IA, is a challenging disease of rice worldwide. In the current study, nine R. solani isolates, within the anastomosis group AG-1 IA, were isolated, characterized based on their macroscopic and microscopic features, as well as their ability to produce cell wall degrading enzymes (CWDEs), and further molecularly identified via ITS sequencing. Although all isolates were pathogenic and produced typical sheath blight symptoms the susceptible rice cultivar, Sakha 101, R. solani AG1 IA -isolate SHBP9 was the most aggressive isolate. The virulence of isolate SHBP9 was correlated with its overproduction of CWDEs, where it had the highest pectinase, amylase, and cellulase activity in vitro. R. solani AG1 IA -isolate SHBP9 was able to infect 12 common rice-associated weeds from the family Poaceae, as well as over 25 economic crops from different families, except chickpea (Cicer arietinum) from Fabaceae, Rocket (Eruca sativa) from Brassicaceae, and the four crops from Solanaceae. Additionally, rice genotype-based resistance was evaluated using 11 rice genotypes for their response to R. solani isolates, morphological traits, yield components, and using 12 SSR markers linked to sheath blight resistance. Briefly, the tested 11 rice genotypes were divided into three groups; Cluster "I" included only two resistant genotypes (Egyptian Yasmine and Giza 182), Cluster "II" included four moderately resistant genotypes (Egyptian hybrid 1, Giza 178, 181, and 183), whereas Cluster "III" included five susceptible (Sakha 104, 101, 108, Super 300 and Giza 177). Correspondingly, only surface-mycelium growth was microscopically noticed on the resistant cultivar Egyptian Yasmine, as well as the moderately resistant Egyptian hybrid 1, however, on the susceptible Sakha 104, the observed mycelium was branched, shrunk, and formed sclerotia. Accordingly, Indica and Indica/Japonica rice genotypes showed more resistance to R. solani than Japonica genotypes. These findings provide insights into its pathogenicity mechanisms and identify potential targets for disease control which ultimately contributes to the development of sustainable eco-friendly disease management strategies. Moreover, our findings might pave the way for developing resistant rice varieties by using more reliable resistance sources of non-host plants, as well as, rice genotype-based resistance as a genetic resource.

Ribo-seq and RNA-seq analyses enrich the regulatory network of tomato fruit cracking

Tomato (Solanum lycopersicum L.), one of the most widely grown vegetable crops in the world, faces cracking problems before and after harvest. Fruit cracking reduces the commercial value and seriously affects the economic performance of the fruits by affecting the appearance and quality of the fruit. Clarifying the molecular mechanism underlying tomato fruit cracking is of great importance for selecting and breeding cracking-resistant varieties. At present, research on the molecular mechanism of tomato fruit cracking has made progress, but few studies have been conducted to explore the genes related to fruit cracking regulation using combined multi-omics analysis. We applied Ribo-seq (ribosome analysis sequencing) and RNA-seq (RNA-sequencing) techniques to uncover potential fruit cracking regulatory genes and improve the regulatory network of fruit cracking using extremely cracking-resistant (CR) and cracking-susceptible (CS) tomato genotypes. Combining these two sets of histological data and translation efficiency, 41 genes were identified to be associated with fruit cracking. The genes played functions on hormone synthesis (e.g. Solyc09g089580.4, Solyc07g049530.3), reactive oxygen species regulation (e.g. Solyc08g080940.3), cell wall metabolism (e.g. Solyc04g071070.2, Solyc03g123630.4), aquaporins activity (e.g. Solyc03g096290.3, Solyc10g083880.2), cuticle and wax composition, as well as mineral elements transport (e.g. Solyc10g006660.3, Solyc01g057770.3), while 10 of them were transcription factors (TF) (e.g. Solyc05g015850.4, Solyc08g078190.2). Based on the investigation of the interaction relationship between these genes, the synergistic regulation of multi-gene tomato fruit cracking was predicted. This study suggests that the synergistic action of transcription and translation is an important molecular mechanism in regulating tomato fruit cracking.

Advances on polymeric nanocarriers for sustainable agriculture: Enhancing dsRNA/siRNA delivery to combat agricultural pests

The application of exogenous RNA for gene-silencing strategies has gained significant traction in agriculture, offering a highly efficient and eco-friendly alternative to conventional plant protection methods. This success has been driven by advances in biotechnology, from the design of long double-stranded RNA (dsRNA) and small interfering RNA (siRNA) molecules to the development of nanocarrier systems that address the challenge of RNA delivery into plant cells. In particular, polymer-based nanocarriers have emerged as a promising solution for enhancing the stability and delivery efficiency of RNA molecules. This review provides a comprehensive overview of the current state of research on the use of polymeric nanocarriers in RNA interference (RNAi) systems for crop protection. It examines key technological developments that have enabled the effective delivery of dsRNA/siRNA to target organisms, with a focus on the unique advantages polymers offer as carriers. Recent studies highlight significant progress in the preparation, characterization, and application of polymeric nanocarriers for RNA encapsulation and delivery. The review also explores the environmental and health challenges posed by these technologies, emphasizing the need for sustainable approaches in their development. Specifically, the production of nanocarriers must adhere to the principles of green chemistry, prioritizing chemical modification routes that reduce harmful residues, such as toxic solvents. Finally, this paper discusses both the current challenges and future prospects of using polymer-based nanocarriers in sustainable agriculture, offering critical insights into their potential to transform crop protection through RNAi technologies.

Optimizing Brassica oleracea L. Breeding Through Somatic Hybridization Using Cytoplasmic Male Sterility (CMS) Lines: From Protoplast Isolation to Plantlet Regeneration

The Brassica oleracea L. species embrace important horticultural crops, such as broccoli, cauliflower, and cabbage, which are highly valued for their beneficial nutritional effects. However, the complexity of flower emasculation in these species has forced breeders to adopt biotechnological approaches such as somatic hybridization to ease hybrid seed production. Protoplasts entail a versatile tool in plant biotechnology, supporting breeding strategies that involve genome editing and hybridization. This review discusses the use of somatic hybridization in B. oleracea L. as a biotechnological method for developing fusion products with desirable agronomic traits, particularly cytoplasmic male sterile (CMS) condition. These CMS lines are critical for implementing a cost-effective, efficient, and reliable system for producing F1 hybrids. We present recent studies on CMS systems in B. oleracea L. crops, providing an overview of established models that explain the mechanisms of CMS and fertility restoration. Additionally, we emphasize key insights gained from protoplast fusion applied to B. oleracea L. breeding. Key steps including pre-treatments of donor plants, the main tissues used as sources of parental protoplasts, methods for obtaining somatic hybrids and cybrids, and the importance of establishing a reliable plant regeneration method are discussed. Finally, the review explores the incorporation of genome editing technologies, such as CRISPR-Cas9, to introduce multiple agronomic traits in Brassica species. This combination of advanced biotechnological tools holds significant promise for enhancing B. oleracea breeding programs in the actual climate change context.

Multi-frequency ultrasonic-assisted enzymatic extraction of coconut paring oil from coconut by-products: Impact on the yield, physicochemical properties, and emulsion stability

Extraction of coconut paring oil (CPO) from processing by-products adds value to the product and reduces resource wastage. This study aims to assess the impact of 20 kHz, 20/80 kHz and 20/40/80 kHz of multi-frequency ultrasonic-assisted enzymatic extraction (MFUAEE) on the yield, physicochemical properties, fatty acid composition, total phenolic content, antioxidant activity, and emulsion stability of CPO derived from wet coconut parings (WCP). Results revealed that the CPO extraction yield with MFUAEE was 32.58 % - 43.31 % higher compared to AEE. The tri-frequency 20/40/80 kHz mode of multi-frequency ultrasound pretreatment exhibited the highest CPO extraction yield (70.08 %). The oil extracted through MFUAEE displayed similar fatty acid profiles to AEE, but had lower peroxide value, K232 and K270 values. Particularly, MFUAEE oil contained higher total phenolic content and exhibited potent DPPH free radical scavenging capacity. Results observed by SEM indicated that the pretreatment with multi-frequency ultrasound more efficiently disrupts the cellular structure of the WCP. Additionally, MFUAEE enhanced emulsion stability through the cavitation effect of ultrasound. These findings suggest that MFUAEE is a valuable approach for method for obtaining CPO with elevated extraction yield and superior quality, thereby enhancing the utilization of coconut by-products.

Roles of Three FgPel Genes in the Development and Pathogenicity Regulation of Fusarium graminearum

Fusarium head blight (FHB) is a devastating fungal disease caused by Fusarium graminearum. Pectin lyase, a pectinase, acts on the α-1,4-glycosidic linkage of galacturonic acid primarily by β-elimination. In this study, three pectin lyase genes (FgPel1, 2, 3) in F. graminearum were selected, and deletion mutants (ΔFgPel1, 2, 3) were constructed by homologous recombination for functional characterization. The gene deletions affected the morphology and growth rate of F. graminearum on pectin medium at various concentrations, with the growth rate of ΔFgPel1 being more significant. The growth of ΔFgPel1 colonies slowed at pH 4, with optimal growth at pH 6.5, whereas ΔFgPel2 and ΔFgPel3 exhibited greater inhibition at pH 8. Colony morphology and diameter of the deletion mutants showed no significant differences compared to the wild-type strain PH-1, and there was no effect on conidial production or germination rate. Pathogenicity assays demonstrated that gene deletion significantly reduced the ability of F. graminearum to infest corn silks and wheat ears, and that ΔFgPel2 showed a more pronounced reduction in pathogenicity on wheat spikes. In summary, the pectin lyase genes (FgPel1, 2, 3) are involved in pectin utilization and are influenced by external pH conditions, which attenuate the pathogenicity of F. graminearum without affecting its vegetative growth or asexual spore formation. These findings elucidate the roles of these genes and provide a basis for controlling FHB.

Genome-wide identification and characterization of pectin methylesterase inhibitor gene family members related to abiotic stresses in watermelon

Pectin is a vital component of plant cell walls and its methylation process is regulated by pectin methylesterase inhibitors (PMEIs). PMEIs regulate the structural and functional modifications of cell walls in plants and play an important role in plant processes such as seed germination, fruit ripening, and stress response. Although the PMEI gene family has been well characterized in model plants, the understanding of its molecular evolution and biological functions in watermelon remains limited. In this study, 60 ClPMEI genes were identified and characterized, revealing their dispersion on multiple chromosomes. Based on a systematic developmental analysis, these genes were classified into three subfamilies, which was further supported by the exon, intron, and conserved motif distribution. Analysis of cis-elements and expression patterns indicated that ClPMEIs might be involved in regulating the tolerance of watermelon to various abiotic stresses. Moreover, distinct ClPMEI genes exhibit specific functions under different abiotic stresses. For example, ClPMEI51 and ClPMEI54 showed a significant upregulation in expression levels during the late stage of drought treatments, whereas ClPMEI3 and ClPMEI12 displayed a significant downregulation under low-temperature induction. Subcellular localization prediction and analysis revealed that the ClPMEI family member proteins were localized to the cell membrane. This study provided an important foundation for the further exploration of the functions of ClPMEI genes in watermelon.

Human Skeletal Muscle Myoblast Culture in Aligned Bacterial Nanocellulose and Commercial Matrices

Bacterial nanocellulose (BNC) is a durable, flexible, and dynamic biomaterial capable of serving a wide variety of fields, sectors, and applications within biotechnology, healthcare, electronics, agriculture, fashion, and others. BNC is produced spontaneously in carbohydrate-rich bacterial culture media, forming a cellulosic pellicle via a nanonetwork of fibrils extruded from certain genera. Herein, we demonstrate engineering BNC-based scaffolds with tunable physical and mechanical properties through postprocessing. Human skeletal muscle myoblasts (HSMMs) were cultured on these scaffolds, and in vitro electrical stimulation was applied to promote cellular function for tissue engineering applications. We compared physiologic maturation markers of human skeletal muscle myoblast development using a 2.5-dimensional culture paradigm in fabricated BNC scaffolds, compared to two-dimensional (2D) controls. We demonstrate that the culture of human skeletal muscle myoblasts on BNC scaffolds developed under electrical stimulation produced highly aligned, physiologic morphology of human skeletal muscle myofibers compared to unstimulated BNC and standard 2D culture. Furthermore, we compared an array of metrics to assess the BNC scaffold in a rigorous head-to-head study with commercially available, clinically approved matrices, Kerecis Omega3 Wound Matrix (Marigen) and Phoenix as well as a gelatin methacryloyl (GelMA) hydrogel. The BNC scaffold outcompeted industry standard matrices as well as a 20% GelMA hydrogel in durability and sustained the support of human skeletal muscle myoblasts in vitro. This work offers a robust demonstration of BNC scaffold cytocompatibility with human skeletal muscle cells and sets the basis for future work in healthcare, bioengineering, and medical implant technological development.

Chemical synthesis of natural and azido-modified UDP-rhamnose and -arabinofuranose for glycan array-based characterization of plant glycosyltransferases

Chemical syntheses of UDP-rhamnose and UDP-arabinofuranose and respective azido-modified analogues are reported. The prepared substrates are useful for the glycan array-based analysis of glycosyltransferases, as exemplified with the plant cell wall-biosynthetic enzymes PvXAT3, AtRRT4 and PtRRT5.

Molecular Insights into the Defense of Dioscorea opposita Cultivar Tiegun Callus Against Pathogenic and Endophytic Fungal Infection Through Transcriptome Analysis

Dioscorea opposita cultivar Tiegun is an economically important crop with high nutritional and medicinal value. Plants can activate complex and diverse defense mechanisms after infection by pathogenic fungi. Moreover, endophytic fungi can also trigger the plant immune system to resist pathogen invasion. However, the study of the effects of endophytic fungi on plant infection lags far behind that of pathogenic fungi, and the underlying mechanism is not fully understood. Here, the black spot pathogen Alternaria alternata and the endophytic fungus Penicillium halotolerans of Tiegun were identified and used to infect calli. The results showed that A. alternata could cause more severe membrane lipid peroxidation, whereas P. halotolerans could rapidly increase the activity of the plant antioxidant enzymes superoxide dismutase, peroxidase, and catalase; thus, the degree of damage to the callus caused by P. halotolerans was weaker than that caused by A. alternata. RNA sequencing analysis revealed that various plant defense pathways, such as phenylpropanoid biosynthesis, flavonoid biosynthesis, plant hormone signal transduction, and the mitogen-activated protein kinase signaling pathway, play important roles in triggering the plant immune response during fungal infection. Furthermore, the tryptophan metabolism, betalain biosynthesis, fatty acid degradation, flavonoid biosynthesis, tyrosine metabolism, and isoquinoline alkaloid biosynthesis pathways may accelerate the infection of pathogenic fungi, and the ribosome biogenesis pathway in eukaryotes may retard the damage caused by endophytic fungi. This study lays a foundation for exploring the infection mechanism of yam pathogens and endophytic fungi and provides insight for effective fungal disease control in agriculture.

Progressive meristem and single-cell transcriptomes reveal the regulatory mechanisms underlying maize inflorescence development and sex differentiation

Maize develops separate ear and tassel inflorescences with initially similar morphology but ultimately different architecture and sexuality. The detailed regulatory mechanisms underlying these changes still remain largely unclear. In this study, through analyzing the time-course meristem transcriptomes and floret single-cell transcriptomes of ear and tassel, we revealed the regulatory dynamics and pathways underlying inflorescence development and sex differentiation. We identified 16 diverse gene clusters with differential spatiotemporal expression patterns and revealed biased regulation of redox, programmed cell death, and hormone signals during meristem differentiation between ear and tassel. Notably, based on their dynamic expression patterns, we revealed the roles of two RNA-binding proteins in regulating inflorescence meristem activity and axillary meristem formation. Moreover, using the transcriptional profiles of 53 910 single cells, we uncovered the cellular heterogeneity between ear and tassel florets. We found that multiple signals associated with either enhanced cell death or reduced growth are responsible for tassel pistil suppression, while part of the gibberellic acid signal may act non-cell-autonomously to regulate ear stamen arrest during sex differentiation. We further showed that the pistil-protection gene SILKLESS 1 (SK1) functions antagonistically to the known pistil-suppression genes through regulating common molecular pathways, and constructed a regulatory network for pistil-fate determination. Collectively, our study provides a deep understanding of the regulatory mechanisms underlying inflorescence development and sex differentiation in maize, laying the foundation for identifying new regulators and pathways for maize hybrid breeding and improvement.

Bifunctional transcription factors SlERF.H5 and H7 activate cell wall and repress gibberellin biosynthesis genes in tomato via a conserved motif

The plant cell wall is a dynamic structure that plays an essential role in development, but the mechanism regulating cell wall formation remains poorly understood. We demonstrate that two transcription factors, SlERF.H5 and SlERF.H7, control cell wall formation and tomato fruit firmness in an additive manner. Knockout of SlERF.H5, SlERF.H7, or both genes decreased cell wall thickness, firmness, and cellulose contents in fruits during early development, especially in double-knockout lines. Overexpressing either gene resulted in thicker cell walls and greater fruit firmness with elevated cellulose levels in fruits but severely dwarf plants with lower gibberellin contents. We further identified that SlERF.H5 and SlERF.H7 activate the cellulose biosynthesis gene SlCESA3 but repress the gibberellin biosynthesis gene GA20ox1. Moreover, we identified a conserved LPL motif in these ERFs responsible for their activities as transcriptional activators and repressors, providing insight into how bifunctional transcription factors modulate distinct developmental processes.

Spectroscopic Investigation of Tomato Seed Germination Stimulated by Trichoderma spp

Seed germination is a complex process that can be negatively affected by numerous stresses. Trichoderma spp. are known as effective biocontrol agents as well as plant growth and germination stimulators. However, understanding of the early interactions between seeds and Trichoderma spp. remains limited. In the present paper, Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to reveal the nature of tomato seed germination as stimulated by Trichoderma. A rapid response of tomato seeds to Trichoderma spp. was observed within 48 h on Murashige and Skoog medium (MS) substrate, preceding any physical contact. Raman analysis indicated that both Trichoderma species stimulated phenolic compound synthesis by triggering plant-specific responses in seed radicles. The impact of T. harzianum and T. brevicompactum on two tomato cultivars resulted in alterations to the middle lamella pectin, cellulose, and xyloglucan in the primary cell wall. The Raman spectra indicated increased xylan content in NA with T9 treatment as well as increased hemicelluloses in GZ with T4 treatment. Moreover, T4 treatment resulted in elevated conjugated aldehydes in lignin in GZ, whereas the trend was reversed in NA. Additionally, FTIR analysis revealed significant changes in total protein levels in Trichoderma spp.-treated tomato seed radicles, with simultaneous decreases in pectin and/or xyloglucan. Our results indicate that two complementary spectroscopic methods, FTIR and Raman spectroscopy, can give valuable information on rapid changes in the plant cell wall structure of tomato radicles during germination stimulated by Trichoderma spp.

Evolutionary dynamics of the cytoskeletal profilin gene family in Brassica juncea L. reveal its roles in silique development and stress resilience

Essential to plant adaptation, cell wall (CW) integrity is maintained by CW-biosynthesis genes. Cytoskeletal actin-(de)polymerizing, phospholipid-binding profilin (PRF) proteins play important roles in maintaining cellular homeostasis across kingdoms. However, evolutionary selection of PRF genes and their systematic characterization in family Brassicaceae, especially in Brassica juncea remain unexplored. Here, a comprehensive analysis of genome-wide identification of BjPRFs, their phylogenetic association, genomic localization, gene structure, and transcriptional profiling were performed in an evolutionary framework. Identification of 23 BjPRFs in B. juncea indicated an evolutionary conservation within Brassicaceae. The BjPRFs evolved through paralogous and orthologous gene formation in Brassica genomes. Evolutionary divergence of BjPRFs indicated purifying selection, with nonsynonymous (dN)/synonymous (dS) value of 0.090 for orthologous gene-pairs. Hybrid homology-modeling identified evolutionary distinct and conserved domains in BjPRFs which suggested that these proteins evolved following the divergence of monocot and eudicot plants. RNA-seq profiles of BjPRFs revealed their functional evolution in spatiotemporal manner during plant-development and stress-conditions in diploid/amphidiploid Brassica species. Real-Time PCR experiments in seedling, vegetative, floral and silique tissues of B. juncea suggested their essential roles in systematic plant development. These observations underscore the expansion of BjPRFs in B. juncea, and offer valuable evolutionary insights for exploring cellular mechanisms, and stress resilience.

Transcriptome analysis and functional verification reveal the roles of copper in resistance to potato virus Y infection in tobacco

Potato virus Y (PVY) is one of the most important pathogens in the genus Potyvirus that seriously harms agricultural production. Copper (Cu), as a micronutrient, is closely related to plant immune response. In this study, we found that foliar application of Cu could inhibit PVY infection to some extent, especially at 7 days post inoculation (dpi). To explore the effect of Cu on PVY infection, transcriptome sequencing analysis was performed on PVY-infected tobacco with or without Cu application. Several key pathways regulated by Cu were identified, including plant-pathogen interaction, inorganic ion transport and metabolism, and photosynthesis. Moreover, the results of virus-induced gene silencing (VIGS) assays revealed that NbMLP423, NbPIP2, NbFd and NbEXPA played positive roles in resistance to PVY infection in Nicotiana benthamiana. In addition, transgenic tobacco plants overexpressing NtEXPA11 showed increased resistance to PVY infection. These results contribute to clarify the role and regulatory mechanism of Cu against PVY infection, and provide candidate genes for disease resistance breeding.

Endogenous cell wall degrading enzyme LytD is important for the biocontrol activity of Bacillus subtilis

Autolysins are endogenous cell wall degrading enzymes (CWDEs) in bacteria that remodel the peptidoglycan layer of its own cell wall. In the Bacillus subtilis genome, at least 35 autolysin genes have been identified. However, the study of their roles in bacterial physiology has been hampered by their complexity and functional redundancy. B. subtilis GLB191 is an effective biocontrol strain against grape downy mildew disease, the biocontrol effect of which results from both direct effect against the pathogen and stimulation of the plant defense. In this study, we show that the autolysin N-acetylglucosaminidase LytD, a major autolysin of vegetative growth in B. subtilis, plays an important role in its biocontrol activity against grape downy mildew. Disruption of lytD resulted in reduced suppression of the pathogen Plasmopara viticola and stimulation of the plant defense. LytD is also shown to affect the biofilm formation and colonization of B. subtilis on grape leaves. This is the first report that demonstrates the role of an endogenous CWDE in suppressing plant disease infection of a biological control microorganism. These findings not only expand our knowledge on the biological function of autolysins but also provide a new target to promote the biocontrol activity of B. subtilis.

Endophytic non-pathogenic Fusarium oxysporum reorganizes the cell wall in flax seedlings

Introduction

Flax (Linum usitatissimum) is a crop producing valuable products like seeds and fiber. However, its cultivation faces challenges from environmental stress factors and significant yield losses due to fungal infections. The major threat is Fusarium oxysporum f.sp lini, causing fusarium wilt of flax. Interestingly, within the Fusarium family, there are non-pathogenic strains known as biocontrols, which protect plants from infections caused by pathogenic strains. When exposed to a non-pathogenic strain, flax exhibits defense responses similar to those seen during pathogenic infections. This sensitization process activates immune reactions, preparing the plant to better combat potential pathogenic strains. The plant cell wall is crucial for defending against pathogens. It serves as the primary barrier, blocking pathogen entry into plant cells.

Methods

The aim of the study was to investigate the effects of treating flax with a non-pathogenic Fusarium oxysporum strain, focusing on cell wall remodeling. The infection's progress was monitored by determining the fungal DNA content and microscopic observation. The plant defense response was confirmed by an increase in the level of Pathogenesis-Related (PR) genes transcripts. The reorganization of flax cell wall during non-pathogenic Fusarium oxysporum strain infection was examined using Infrared spectroscopy (IR), determination of cell wall polymer content, and analysis of mRNA level of genes involved in their metabolism.

Results and discussion

IR analysis revealed reduced cellulose content in flax seedlings after treatment with Fo47 and that the cellulose chains were shorter and more loosely bound. Hemicellulose content was also reduced but only after 12h and 36h. The total pectin content remained unchanged, while the relative share of simple sugars and uronic acids in the pectin fractions changed over time. In addition, a dynamic change in the level of methylesterification of carboxyl groups of pectin was observed in flax seedlings treated with Fo47 compared to untreated seedlings. The increase in lignin content was observed only 48 hours after the treatment with non-pathogenic Fusarium oxysporum. Analysis of mRNA levels of cell wall polymer metabolism genes showed significant changes over time in all analyzed genes. In conclusion, the research suggests that the rearrangement of the cell wall is likely one of the mechanisms behind flax sensitization by the non-pathogenic Fusarium oxysporum strain. Understanding these processes could help in developing strategies to enhance flax's resistance to fusarium wilt and improve its overall yield and quality.

Phytoremediation of copper-contaminated soils by rapeseed (Brassica napus L.) and underlying molecular mechanisms for copper absorption and sequestration

High levels of copper released in the soil, mainly from anthropogenic activity, can be hazardous to plants, animals, and humans. The present research aimed to estimate the suitability and effectiveness of rapeseed (Brassica napus L.) as a possible soil remediation option and to uncover underlying adaptive mechanisms A pot experiment was conducted to explore the effect of copper stress on agronomic and yield traits for 32 rapeseed genotypes. The copper-tolerant genotype H2009 and copper-sensitive genotype ZYZ16 were selected for further physiological, metabolomic, and transcriptomic analyses. The results exhibited a significant genotypic variation in copper stress tolerance in rapeseed. Specifically, the ratio of seed yield under copper stress to control ranged from 0.29 to 0.74. Furthermore, the proline content and antioxidant enzymatic activities in the roots were greater than those in the shoots. The accumulated copper in the roots accounted for about 50% of the total amount absorbed by plants; thus, the genotypes possessing high root volumes can be used for rhizofiltration to uptake and sequester copper. Additionally, the pectin and hemicellulose contents were significantly increased by 15.6% and 162%, respectively, under copper stress for the copper-tolerant genotype, allowing for greater sequestration of copper ions in the cell wall and lower oxidative stress. Comparative analysis of transcriptomes and metabolomes revealed that excessive copper enhanced the up-regulation of functional genes or metabolites related to cell wall binding, copper transportation, and chelation in the copper-tolerant genotype. Our results suggest that copper-tolerant rapeseed can thrive in heavily copper-polluted soils with a 5.85% remediation efficiency as well as produce seed and vegetable oil without exceeding food quality standards for the industry. This multi-omics comparison study provides insights into breeding copper-tolerant genotypes that can be used for the phytoremediation of heavy metal-polluted soils.

Epigenetic weapons of plants against fungal pathogens

In the natural environment, plants face constant exposure to biotic stress caused by fungal attacks. The plant's response to various biotic stresses relies heavily on its ability to rapidly adjust the transcriptome. External signals are transmitted to the nucleus, leading to activation of transcription factors that subsequently enhance the expression of specific defense-related genes. Epigenetic mechanisms, including histone modifications and DNA methylation, which are closely linked to chromatin states, regulate gene expression associated with defense against biotic stress. Additionally, chromatin remodelers and non-coding RNA play a significant role in plant defense against stressors. These molecular modifications enable plants to exhibit enhanced resistance and productivity under diverse environmental conditions. Epigenetic mechanisms also contribute to stress-induced environmental epigenetic memory and priming in plants, enabling them to recall past molecular experiences and utilize this stored information for adaptation to new conditions. In the arms race between fungi and plants, a significant aspect is the cross-kingdom RNAi mechanism, whereby sRNAs can traverse organismal boundaries. Fungi utilize sRNA as an effector molecule to silence plant resistance genes, while plants transport sRNA, primarily through extracellular vesicles, to pathogens in order to suppress virulence-related genes. In this review, we summarize contemporary knowledge on epigenetic mechanisms of plant defense against attack by pathogenic fungi. The role of epigenetic mechanisms during plant-fungus symbiotic interactions is also considered.

Discovery and Characterization of Fluopipamine, a Putative Cellulose Synthase 1 Antagonist within Arabidopsis

Herbicide-resistant weeds are increasingly a problem in crop fields when exposed to similar chemistry over time. To avoid future yield losses, identifying herbicidal chemistry needs to be accelerated. We screened 50,000 small molecules using a liquid-handling robot and light microscopy focusing on pre-emergent herbicides in the family of cellulose biosynthesis inhibitors. Through phenotypic, chemical, genetic, and in silico methods we uncovered 6-{[4-(2-fluorophenyl)-1-piperazinyl]methyl}-N-(2-methoxy-5-methylphenyl)-1,3,5-triazine-2,4-diamine (fluopipamine). Symptomologies support fluopipamine as a putative antagonist of cellulose synthase enzyme 1 (CESA1) from Arabidopsis (Arabidopsis thaliana). Ectopic lignification, inhibition of etiolation, phenotypes including loss of anisotropic cellular expansion, swollen roots, and live cell imaging link fluopipamine to cellulose biosynthesis inhibition. Radiolabeled glucose incorporation of cellulose decreased in short-duration experiments when seedlings were incubated in fluopipamine. To elucidate the mechanism, ethylmethanesulfonate mutagenized M2 seedlings were screened for fluopipamine resistance. Two loci of genetic resistance were linked to CESA1. In silico docking of fluopipamine, quinoxyphen, and flupoxam against various CESA1 mutations suggests that an alternative binding site at the interface between CESA proteins is necessary to preserve cellulose polymerization in compound presence. These data uncovered potential fundamental mechanisms of cellulose biosynthesis in plants along with feasible leads for herbicidal uses.

Genome-wide analysis and characterization of the TaTLP gene family in wheat and functional characterization of the TaTLP44 in response to Rhizoctonia cerealis

Wheat sharp eyespot is a soil-borne disease caused by Rhizoctonia cerealis, which occurs in many countries worldwide and significantly reduces the yield. Thaumatin-like protein (TLP), also known as PR5, is a member of the pathogen response protein family and plays an essential role in plant resistance to pathogen infection. In this study, 131 TaTLP genes were identified from the wheat genome, of which 38 TaTLPs were newly discovered. The TaTLP gene family contains many tandem duplications and fragment duplications, which is a major pathway for gene amplification. Besides, we also analyzed the physicochemical properties, gene structure and promoter cis-acting regulatory elements of all the TaTLP genes. In addition, the expression patterns of nine TaTLPs in response to R. cerealis were analyzed by RT-qPCR. Six TaTLP proteins expressed in vitro had no significant inhibitory effect on R. cerealis, suggesting that these TaTLP proteins may function in other ways. Finally, we performed gene silencing of TaTLP44 in wheat, which increased the expression of some defense-associated genes and improved resistance to R. cerealis. In summary, we systematically analyzed TaTLP family members and demonstrated that TaTLP44 negatively regulates the resistance to R. cerealis by controlling expression of defense-associated genes. These results provide new insights into the functional mechanism of TaTLP proteins.

Understanding the Molecular Regulatory Networks of Seed Size in Soybean

Soybean being a major cash crop provides half of the vegetable oil and a quarter of the plant proteins to the global population. Seed size traits are the most important agronomic traits determining the soybean yield. These are complex traits governed by polygenes with low heritability as well as are highly influenced by the environment as well as by genotype x environment interactions. Although, extensive efforts have been made to unravel the genetic basis and molecular mechanism of seed size in soybean. But most of these efforts were majorly limited to QTL identification, and only a few genes for seed size were isolated and their molecular mechanism was elucidated. Hence, elucidating the detailed molecular regulatory networks controlling seed size in soybeans has been an important area of research in soybeans from the past decades. This paper describes the current progress of genetic architecture, molecular mechanisms, and regulatory networks for seed sizes of soybeans. Additionally, the main problems and bottlenecks/challenges soybean researchers currently face in seed size research are also discussed. This review summarizes the comprehensive and systematic information to the soybean researchers regarding the molecular understanding of seed size in soybeans and will help future research work on seed size in soybeans.

Exogenous abscisic acid treatment regulates protein secretion in sorghum cell suspension cultures

Drought stress adversely affects plant growth, often leading to total crop failure. Upon sensing soil water deficits, plants switch on biosynthesis of abscisic acid (ABA), a stress hormone for drought adaptation. Here, we used exogenous ABA application to dark-grown sorghum cell suspension cultures as an experimental system to understand how a drought-tolerant crop responds to ABA. We evaluated intracellular and secreted proteins using isobaric tags for relative and absolute quantification. While the abundance of only ~ 7% (46 proteins) intracellular proteins changed in response to ABA, ~32% (82 proteins) of secreted proteins identified in this study were ABA responsive. This shows that the extracellular matrix is disproportionately targeted and suggests it plays a vital role in sorghum adaptation to drought. Extracellular proteins responsive to ABA were predominantly defense/detoxification and cell wall-modifying enzymes. We confirmed that sorghum plants exposed to drought stress activate genes encoding the same proteins identified in the in vitro cell culture system with ABA. Our results suggest that ABA activates defense and cell wall remodeling systems during stress response. This could underpin the success of sorghum adaptation to drought stress.

Altered cell wall hydroxycinnamate composition impacts leaf- and canopy-level CO2 uptake and water use in rice

Cell wall properties play a major role in determining photosynthetic carbon uptake and water use through their impact on mesophyll conductance (CO2 diffusion from substomatal cavities into photosynthetic mesophyll cells) and leaf hydraulic conductance (water movement from xylem, through leaf tissue, to stomata). Consequently, modification of cell wall (CW) properties might help improve photosynthesis and crop water use efficiency (WUE). We tested this using 2 independent transgenic rice (Oryza sativa) lines overexpressing the rice OsAT10 gene (encoding a "BAHD" CoA acyltransferase), which alters CW hydroxycinnamic acid content (more para-coumaric acid and less ferulic acid). Plants were grown under high and low water levels, and traits related to leaf anatomy, CW composition, gas exchange, hydraulics, plant biomass, and canopy-level water use were measured. Alteration of hydroxycinnamic acid content led to statistically significant decreases in mesophyll CW thickness (-14%) and increased mesophyll conductance (+120%) and photosynthesis (+22%). However, concomitant increases in stomatal conductance negated the increased photosynthesis, resulting in no change in intrinsic WUE (ratio of photosynthesis to stomatal conductance). Leaf hydraulic conductance was also unchanged; however, transgenic plants showed small but statistically significant increases in aboveground biomass (AGB) (+12.5%) and canopy-level WUE (+8.8%; ratio of AGB to water used) and performed better under low water levels than wild-type plants. Our results demonstrate that changes in CW composition, specifically hydroxycinnamic acid content, can increase mesophyll conductance and photosynthesis in C3 cereal crops such as rice. However, attempts to improve photosynthetic WUE will need to enhance mesophyll conductance and photosynthesis while maintaining or decreasing stomatal conductance.

Cell Wall Pectin Content Refers to Favored Delivery of Negatively Charged Carbon Dots in Leaf Cells

In this work, we systematically investigated how cell wall and cell wall components affect the delivery of charged carbon quantum dots (CDs, from -34 to +41 mV) to leaf cells of cucumber and Arabidopsis plants. Four different types of leaf cells in cucumber and Arabidopsis were used, i.e., protoplasts (without cell wall), isolated individual cells (cell wall hydrolyzed with pectinase), regenerated individual cells (cell wall regenerated from protoplast), and intact leaf cells (intact cell wall, in planta). Leaf cells were incubated with charged CDs (0.5 mg/mL) for 2 h. Confocal imaging results showed that protoplasts, regenerated individual cells, and leaf cells showed favored uptake of the negatively charged CDs (-34 mV) compared to the PEI (polyethylenimine) coated and positively charged carbon dots [PEI600-CDs (17 mV) and PEI10K-CDs (41 mV)], while in isolated individual cells, the trend is opposite. The results of the content of the cell wall components showed that no significant changes in the total cell wall content were found between isolated individual cells and regenerated individual cells (1.28 vs 1.11 mg/106 cells), while regenerated individual cells showed significant higher pectin content [water-soluble pectin (0.13 vs 0.06 mg/106 cells, P < 0.01), chelator-soluble pectin (0.04 vs 0.01 mg/106 cells, P < 0.01), and alkaline pectin (0.02 vs 0.01 mg/106 cells, P < 0.01)] and significant lower cellulose content (0.13 vs 0.32 mg/106 cells, P < 0.01) than the isolated individual cells. No difference of the hemicellulose content was found between isolated individual cells and regenerated individual cells (0.20 vs 0.21 mg/106 cells). Our results suggest that compared with cellulose and hemicellulose in the cell wall, the pectin is a more important factor referring to the favored uptake of negatively charged carbon dots in leaf cells. Overall, this work provides a method to study the role of cell wall components in the uptake of nanoparticles in plant cells and also points out the importance of understanding the interactions between cell barriers and nanoparticles to design nanoparticles for agricultural use.

Gut microbial communities and their potential roles in cellulose digestion and thermal adaptation of earthworms

Adaptations to temperature and food resources, which can be affected by gut microbiota, are two main adaptive strategies allowing soil fauna to survive in their habitats, especially for cold-blooded animals. Earthworms are often referred to as ecosystem engineers because they make up the biggest component of the animal biomass found in the soil. They are considered as an important indicator in the triangle of soil quality, health and functions. However, the roles of gut microbiota in the environmental adaptation of earthworms at a large scale remain obscure. We explored the gut bacterial communities and their functions in the environmental adaptation of two widespread earthworm species (Eisenia nordenskioldi Eisen and Drawida ghilarovi Gates) in Northeast China (1661 km). Based on our findings, the alpha diversity of gut bacterial communities decreased with the increase of latitude, and the gut bacterial community composition was shaped by both mean annual temperature (MAT) and cellulose. Actinobacteria, Proteobacteria, Firmicutes, and Planctomycetes, recognized as the predominant cellulose degraders, were keystone taxa driving gut bacterial interactions. Actinobacteria, Firmicutes, and Planctomycetes were influenced by MAT and cellulose, and had higher contributions to gut total cellulase activity. The optimal temperature for total cellulase in the gut of E. nordenskioldi (25-30 °C) was lower than that of D ghilarovi (40 °C). The gut microbiota-deleted earthworms had the lowest cellulose degradation rate (1.07 %). The cellulose was degraded faster by gut bacteria from the host they were derived, indicating the presence of home field advantage of cellulose decomposition. This study provides a foundation for understanding the biotic strategies adopted by earthworms when they enter a new habitat, with gut microbiota being central to food digestion and environmental adaptability.

Electrostatics Control Nanoparticle Interactions with Model and Native Cell Walls of Plants and Algae

A lack of mechanistic understanding of nanomaterial interactions with plants and algae cell walls limits the advancement of nanotechnology-based tools for sustainable agriculture. We systematically investigated the influence of nanoparticle charge on the interactions with model cell wall surfaces built with cellulose or pectin and performed a comparative analysis with native cell walls of Arabidopsis plants and green algae (Choleochaete). The high affinity of positively charged carbon dots (CDs) (46.0 ± 3.3 mV, 4.3 ± 1.5 nm) to both model and native cell walls was dominated by the strong ionic bonding between the surface amine groups of CDs and the carboxyl groups of pectin. In contrast, these CDs formed weaker hydrogen bonding with the hydroxyl groups of cellulose model surfaces. The CDs of similar size with negative (-46.2 ± 1.1 mV, 6.6 ± 3.8 nm) or neutral (-8.6 ± 1.3 mV, 4.3 ± 1.9 nm) ζ-potentials exhibited negligible interactions with cell walls. Real-time monitoring of CD interactions with model pectin cell walls indicated higher absorption efficiency (3.4 ± 1.3 10-9) and acoustic mass density (313.3 ± 63.3 ng cm-2) for the positively charged CDs than negative and neutral counterparts (p < 0.001 and p < 0.01, respectively). The surface charge density of the positively charged CDs significantly enhanced these electrostatic interactions with cell walls, pointing to approaches to control nanoparticle binding to plant biosurfaces. Ca2+-induced cross-linking of pectin affected the initial absorption efficiency of the positively charged CD on cell wall surfaces (∼3.75 times lower) but not the accumulation of the nanoparticles on cell wall surfaces. This study developed model biosurfaces for elucidating fundamental interactions of nanomaterials with cell walls, a main barrier for nanomaterial translocation in plants and algae in the environment, and for the advancement of nanoenabled agriculture with a reduced environmental impact.

Chitosan nanoparticles upregulate C and N metabolism in soybean plants grown under elevated levels of atmospheric carbon dioxide

Despite the wide utilization of chitosan nanoparticles (CSNPs) as a promising approach for sustainable agriculture, their efficiency under elevated CO2 (eCO2), has not been evaluated. The interactive effects of CSNPs and eCO2 were evaluated on the growth and C and N metabolism of soybean plants. Plants were treated with CSNPs and grown under ambient CO2 (410 ppm, aCO2) or eCO2 (645 ppm). Regardless of CO2 level, CSNPs improved the net photosynthetic rate. CSNPs aggravated the effect of eCO2 treatment on the levels of non-structural carbohydrates (i.e., glucose, fructose, sucrose, and starch), especially in shoots, which was inconsistence with the upregulation of carbohydrates metabolizing enzymes. Being the most pivotal energetic and signaling organic compounds in higher plants, the synergistic action of CSNPs and eCO2 on the accumulation of soluble sugars upregulated the N metabolism as indicated by induced activities of nitrate reductase, arginase, glutamate dehydrogenase, glutamine synthetase, and glutamine oxoglutarate aminotransferase which was manifested finally as increased shoot and root total nitrogen content as well as proline and aspartate in roots. At the hormonal level, the coexistence of eCO2 with CSNPs further supports their positive impact on the contents of IAA and, to a lesser extent, GAs. The present data prove that the biofertilization capacity of CSNPs is even more potent under futuristic eCO2 levels and could even further improve the growth and resilience of plants.

Functional Diversification and the Plant Secondary Cell Wall

Much evidence exists suggesting the presence of genetic functional diversification in plants, though literature associated with the role of functional diversification in the evolution of the plant secondary cell wall (SCW) has sparsely been compiled and reviewed in a recent context. This review aims to elucidate, through the examination of gene phylogenies associated with its biosynthesis and maintenance, the role of functional diversification in shaping the critical, dynamic, and characteristic organelle, the secondary cell wall. It will be asserted that gene families resulting from gene duplication and subsequent functional divergence are present and are heavily involved in SCW biosynthesis and maintenance. Furthermore, diversification will be presented as a significant driver behind the evolution of the many functional characteristics of the SCW. The structure and function of the plant cell wall and its constituents will first be explored, followed by a discussion on the phenomenon of gene duplication and the resulting genetic functional divergence that can emerge. Finally, the major constituents of the SCW and their individual relationships with duplication and divergence will be reviewed to the extent of current knowledge on the subject.

SMALL PLANT AND ORGAN 1 (SPO1) Encoding a Cellulose Synthase-like Protein D4 (OsCSLD4) Is an Important Regulator for Plant Architecture and Organ Size in Rice

Plant architecture and organ size are considered as important traits in crop breeding and germplasm improvement. Although several factors affecting plant architecture and organ size have been identified in rice, the genetic and regulatory mechanisms remain to be elucidated. Here, we identified and characterized the small plant and organ 1 (spo1) mutant in rice (Oryza sativa), which exhibits narrow and rolled leaf, reductions in plant height, root length, and grain width, and other morphological defects. Map-based cloning revealed that SPO1 is allelic with OsCSLD4, a gene encoding the cellulose synthase-like protein D4, and is highly expressed in the roots at the seedling and tillering stages. Microscopic observation revealed the spo1 mutant had reduced number and width in leaf veins, smaller size of leaf bulliform cells, reduced cell length and cell area in the culm, and decreased width of epidermal cells in the outer glume of the grain. These results indicate the role of SPO1 in modulating cell division and cell expansion, which modulates plant architecture and organ size. It is showed that the contents of endogenous hormones including auxin, abscisic acid, gibberellin, and zeatin tested in the spo1 mutant were significantly altered, compared to the wild type. Furthermore, the transcriptome analysis revealed that the differentially expressed genes (DEGs) are significantly enriched in the pathways associated with plant hormone signal transduction, cell cycle progression, and cell wall formation. These results indicated that the loss of SPO1/OsCSLD4 function disrupted cell wall cellulose synthase and hormones homeostasis and signaling, thus leading to smaller plant and organ size in spo1. Taken together, we suggest the functional role of SPO1/OsCSLD4 in the control of rice plant and organ size by modulating cell division and expansion, likely through the effects of multiple hormonal pathways on cell wall formation.

Influence of flowering on the anatomical structure, chemical components and carbohydrate metabolism of Bambusa tuldoides culms at different ages

Bamboo forests, which have come to occupy large areas in recent years, naturally undergo the process of blooming. However, bamboo culms and rhizomes degenerate after the plants bloom, resulting in widespread loss of raw materials. Systematic research on the properties and physiology of bamboo culms after flowering is lacking, and whether flowering bamboo culms could be used as raw materials in industry is unclear. In this paper, we compared and measured the fiber morphology, chemical components, and sugar metabolism indexes of non-flowering and flowering Bambusa tuldoides culms at different ages. The results showed that the fibers in the middle internodes of both non-flowering and flowering B. tuldoides culms had the longest length. The fibers completed their elongation within 1 year, but the fiber walls were continually deposited with age. The levels of the chemical components in the nonflowering culms also continually increased with age. The nonstructural carbohydrate (NSC) content and sugar metabolism indexes showed the highest levels in the 2-year culms and then declined in the 3-year culms. Compared to young culms that had not yet flowered, the 3-month-old and 1-year-old flowering culms had a significant decrease in the fiber length and tangential diameter, and their holocellulose and lignin levels also decreased, while the levels of ash, SiO2, 1% NaOH extractives, and benzene-ethanol extractives increased. A correlation analysis showed that sugar catabolism was accelerated in the flowering cluster, which could lead to "starvation death" in bamboo and which had a significant negative impact on the anatomical and chemical properties of the bamboo culms. Generally, the flowering bamboo culms had shorter fibers, higher levels of extractives and ash, and lower holocellulose content, which indicated that bamboo flowering has an adverse effect on the application of such components in the production of pulp, in papermaking, and in other processing and utilization activities. This study revealed the physiological changes in flowering B. tuldoides culms and provided a theoretical basis to inform the utilization of culms in this species.

Nyctinastic movement in legumes: Developmental mechanisms, factors and biological significance

In legumes, a common phenomenon known as nyctinastic movement is observed. This movement involves the horizontal expansion of leaves during the day and relative vertical closure at night. Nyctinastic movement is driven by the pulvinus, which consists of flexor and extensor motor cells. The turgor pressure difference between these two cell types generates a driving force for the bending and deformation of the pulvinus. This review focuses on the developmental mechanisms of the pulvinus, the factors affecting nyctinastic movement, and the biological significance of this phenomenon in legumes, thus providing a reference for further research on nyctinastic movement.

Tissue Morphogenesis Through Dynamic Cell and Matrix Interactions

Multicellular organisms generate tissues of diverse shapes and functions from cells and extracellular matrices. Their adhesion molecules mediate cell-cell and cell-matrix interactions, which not only play crucial roles in maintaining tissue integrity but also serve as key regulators of tissue morphogenesis. Cells constantly probe their environment to make decisions: They integrate chemical and mechanical information from the environment via diffusible ligand- or adhesion-based signaling to decide whether to release specific signaling molecules or enzymes, to divide or differentiate, to move away or stay, or even whether to live or die. These decisions in turn modify their environment, including the chemical nature and mechanical properties of the extracellular matrix. Tissue morphology is the physical manifestation of the remodeling of cells and matrices by their historical biochemical and biophysical landscapes. We review our understanding of matrix and adhesion molecules in tissue morphogenesis, with an emphasis on key physical interactions that drive morphogenesis.

The Resistance of Maize to Ustilago maydis Infection Is Correlated with the Degree of Methyl Esterification of Pectin in the Cell Wall

Common smut caused by Ustilago maydis is one of the dominant fungal diseases in plants. The resistance mechanism to U. maydis infection involving alterations in the cell wall is poorly studied. In this study, the resistant single segment substitution line (SSSL) R445 and its susceptible recurrent parent line Ye478 of maize were infected with U. maydis, and the changes in cell wall components and structure were studied at 0, 2, 4, 8, and 12 days postinfection. In R445 and Ye478, the contents of cellulose, hemicellulose, pectin, and lignin increased by varying degrees, and pectin methylesterase (PME) activity increased. The changes in hemicellulose and pectin in the cell wall after U. maydis infection were analyzed via immunolabeling using monoclonal antibodies against hemicellulsic xylans and high/low-methylated pectin. U. maydis infection altered methyl esterification of pectin, and the degree of methyl esterification was correlated with the resistance of maize to U. maydis. Furthermore, the relationship between methyl esterification of pectin and host resistance was validated using 15 maize inbred lines with different resistance levels. The results revealed that cell wall components, particularly pectin, were important factors affecting the colonization and propagation of U. maydis in maize, and methyl esterification of pectin played a role in the resistance of maize to U. maydis infection.

Comparison of the Formation of Plant-Microbial Interface in Pisum sativum L. and Medicago truncatula Gaertn. Nitrogen-Fixing Nodules

Different components of the symbiotic interface play an important role in providing positional information during rhizobial infection and nodule development: successive changes in cell morphology correspond to subsequent changes in the molecular architecture of the apoplast and the associated surface structures. The localisation and distribution of pectins, xyloglucans, and cell wall proteins in symbiotic nodules of Pisum sativum and Medicago truncatula were studied using immunofluorescence and immunogold analysis in wild-type and ineffective mutant nodules. As a result, the ontogenetic changes in the symbiotic interface in the nodules of both species were described. Some differences in the patterns of distribution of cell wall polysaccharides and proteins between wild-type and mutant nodules can be explained by the activation of defence reaction or premature senescence in mutants. The absence of fucosylated xyloglucan in the cell walls in the P. sativum nodules, as well as its predominant accumulation in the cell walls of uninfected cells in the M. truncatula nodules, and the presence of the rhamnogalacturonan I (unbranched) backbone in meristematic cells in P. sativum can be attributed to the most striking species-specific features of the symbiotic interface.

Whole genome sequencing and analysis of multiple isolates of Ceratocystis destructans, the causal agent of Ceratocystis canker of almond in California

Ceratocystis canker caused by Ceratocystis destructans is a severe disease of almond, reducing the longevity and productivity of infected trees. Once the disease has established in an individual tree, there is no cure, and management efforts are often limited to removing the infected area of cankers. In this study, we present the genome assemblies of five C. destructans isolates isolated from symptomatic almond trees. The genomes were assembled into a genome size of 27.2 ± 0.9 Mbp with an average of 6924 ± 135 protein-coding genes and an average GC content of 48.8 ± 0.02%. We concentrated our efforts on identifying putative virulence factors of canker pathogens. Analysis of the secreted carbohydrate-active enzymes showed that the genomes harbored 83.4 ± 1.8 secreted CAZymes. The secreted CAZymes covered all the known categories of CAZymes. AntiSMASH revealed that the genomes had at least 7 biosynthetic gene clusters, with one of the non-ribosomal peptide synthases encoding dimethylcoprogen, a conserved virulence determinant of plant pathogenic ascomycetes. From the predicted proteome, we also annotated cytochrome P450 monooxygenases, and transporters, these are well-established virulence determinants of canker pathogens. Moreover, we managed to identify 57.4 ± 2.1 putative effector proteins. Gene Ontology (GO) annotation was applied to compare gene content with two closely related species C. fimbriata, and C. albifundus. This study provides the first genome assemblies for C. destructans, expanding genomic resources for an important almond canker pathogen. The acquired knowledge provides a foundation for further advanced studies, such as molecular interactions with the host, which is critical for breeding for resistance.

Galls induced by a root-knot nematode in Petroselinum crispum (Mill.): impacts on host development, histology, and cell wall dynamics

Infection by the root-knot nematode (RKN), Meloidogyne incognita, impacts crop productivity worldwide, including parsley cultures (Petroselinum crispum). Meloidogyne infection involves a complex relationship between the pathogen and the host plant tissues, leading to the formation of galls and feeding sites that disorganize the vascular system, affecting the development of cultures. Herein, we sought to evaluate the impact of RKN on the agronomic traits, histology, and cell wall components of parsley, with emphasis on giant cell formation. The study consisted of two treatments: (i) control, where 50 individuals of parsley grew without M. incognita inoculation; and (ii) inoculated plants, where 50 individuals were exposed to juveniles (J2) of M. incognita. Meloidogyne incognita infection affected the development of parsley, reducing the growth of some agronomical characteristics such as root weight and shoot weight and height. Giant cell formation was noticed at 18 days after inoculation, promoting disorganization of the vascular system. Epitopes of HGs detected in giant cells reveal the continuous capacity of giant cells to elongate under the stimulus of RKN, essential processes for feeding site establishment. In addition, the detection of epitopes of HGs with low and high methyl-esterified groups indicates the PMEs activity despite biotic stress.

Glycome profiling and immunohistochemistry uncover changes in cell walls of Arabidopsis thaliana roots during spaceflight

A large and diverse library of glycan-directed monoclonal antibodies (mAbs) was used to determine if plant cell walls are modified by low-gravity conditions encountered during spaceflight. This method called glycome profiling (glycomics) revealed global differences in non-cellulosic cell wall epitopes in Arabidopsis thaliana root extracts recovered from RNA purification columns between seedlings grown on the International Space Station-based Vegetable Production System and paired ground (1-g) controls. Immunohistochemistry on 11-day-old seedling primary root sections showed that ten of twenty-two mAbs that exhibited spaceflight-induced increases in binding through glycomics, labeled space-grown roots more intensely than those from the ground. The ten mAbs recognized xyloglucan, xylan, and arabinogalactan epitopes. Notably, three xylem-enriched unsubstituted xylan backbone epitopes were more intensely labeled in space-grown roots than in ground-grown roots, suggesting that the spaceflight environment accelerated root secondary cell wall formation. This study highlights the feasibility of glycomics for high-throughput evaluation of cell wall glycans using only root high alkaline extracts from RNA purification columns, and subsequent validation of these results by immunohistochemistry. This approach will benefit plant space biological studies because it extends the analyses possible from the limited amounts of samples returned from spaceflight and help uncover microgravity-induced tissue-specific changes in plant cell walls.

Syntaxin of plants71 plays essential roles in plant development and stress response via regulating pH homeostasis

SYP71, a plant-specific Qc-SNARE with multiple subcellular localization, is essential for symbiotic nitrogen fixation in nodules in Lotus, and is implicated in plant resistance to pathogenesis in rice, wheat and soybean. Arabidopsis SYP71 is proposed to participate in multiple membrane fusion steps during secretion. To date, the molecular mechanism underlying SYP71 regulation on plant development remains elusive. In this study, we clarified that AtSYP71 is essential for plant development and stress response, using techniques of cell biology, molecular biology, biochemistry, genetics, and transcriptomics. AtSYP71-knockout mutant atsyp71-1 was lethal at early development stage due to the failure of root elongation and albinism of the leaves. AtSYP71-knockdown mutants, atsyp71-2 and atsyp71-3, had short roots, delayed early development, and altered stress response. The cell wall structure and components changed significantly in atsyp71-2 due to disrupted cell wall biosynthesis and dynamics. Reactive oxygen species homeostasis and pH homeostasis were also collapsed in atsyp71-2. All these defects were likely resulted from blocked secretion pathway in the mutants. Strikingly, change of pH value significantly affected ROS homeostasis in atsyp71-2, suggesting interconnection between ROS and pH homeostasis. Furthermore, we identified AtSYP71 partners and propose that AtSYP71 forms distinct SNARE complexes to mediate multiple membrane fusion steps in secretory pathway. Our findings suggest that AtSYP71 plays an essential role in plant development and stress response via regulating pH homeostasis through secretory pathway.

Identification of ZmBK2 Gene Variation Involved in Regulating Maize Brittleness

Maize stalk strength is a crucial agronomic trait that affects lodging resistance. We used map-based cloning and allelic tests to identify a maize mutant associated with decreased stalk strength and confirmed that the mutated gene, ZmBK2, is a homolog of Arabidopsis AtCOBL4, which encodes a COBRA-like glycosylphosphatidylinositol (GPI)-anchored protein. The bk2 mutant exhibited lower cellulose content and whole-plant brittleness. Microscopic observations showed that sclerenchymatous cells were reduced in number and had thinner cell walls, suggesting that ZmBK2 affects the development of cell walls. Transcriptome sequencing of differentially expressed genes in the leaves and stalks revealed substantial changes in the genes associated with cell wall development. We constructed a cell wall regulatory network using these differentially expressed genes, which revealed that abnormal cellulose synthesis may be a reason for brittleness. These results reinforce our understanding of cell wall development and provide a foundation for studying the mechanisms underlying maize lodging resistance.

Functional characterization of TBL genes revealed the role of GhTBL7 and GhTBL58 in cotton fiber elongation

TBL (Trichome Birefringence Like) gene family members are involved in trichome initiation and xylan acetylation in several plant species. In our research, we identified 102 TBLs from G. hirsutum. The phylogenetic tree classified TBL genes into five groups. Collinearity analysis of TBL genes indicated 136 paralogous gene pairs in G. hirsutum. Gene duplication indicated that WGD or segmental duplication contributed to the GhTBL gene family expansion. Promoter cis-elements of GhTBLs were related to growth and development, seed-specific regulation, light, and stress responses. GhTBL genes (GhTBL7, GhTBL15, GhTBL21, GhTBL25, GhTBL45, GhTBL54, GhTBL67, GhTBL72, and GhTBL77) exhibited upregulated response under exposure to cold, heat, NaCl, and PEG. GhTBL genes exhibited high expression during fiber development stages. Two GhTBL genes (GhTBL7 and GhTBL58) showed differential expression at 10 DPA fiber, as 10 DPA is a fast fiber elongation stage and fiber elongation is a very important stage of cotton fiber development. Subcellular localization of GhTBL7 and GhTBL58 revealed that these genes reside inside the cell membrane. Promoter GUS activity of GhTBL7 and GhTBL58 exhibited deep staining in roots. To further validate the role of these genes in cotton fiber elongation, we silenced these genes and observed a significant reduction in the fiber length at 10 DPA. In conclusion, the functional study of cell membrane-associated genes (GhTBL7 and GhTBL58) showed deep staining in root tissues and potential function during cotton fiber elongation at 10 DPA fiber.

Genetic Variation among Heterodera schachtii Populations Coincided with Differences in Invasion and Propagation in Roots of a Set of Cruciferous Plants

Genes of host plants and parasitic nematodes govern the plant-nematode interaction. The biological receptors and parasitism effectors are variable among plant species and nematode populations, respectively. In the present study, hatch testing and bioassays on cabbage, oilseed radish, and mustard were conducted to compare the biological characteristics among six populations of the beet cyst nematode Heterodera schachtii. Genetic patterns of the vap1 gene for the studied populations were distinct as shown by denaturing the gradient gel electrophoresis of PCR-amplified gene fragments. Concurrently, significant differences in the hatching rates, number of penetrated J2 in roots, and eggs/cyst ratios among the six nematode populations for the three cruciferous species were observed. In conclusion, analyzing the population genetic structure of H. schachtii plays a pivotal role in illustrating the variability in the plant-nematode interaction among its populations and plant species, which in its role leads to developing nematode management depending on plant resistance.

Transcriptome analysis of gene expression profiles reveals wood formation mechanisms in Chinese fir at different stand ages

Forests are crucial sustainable sources of natural ecosystems and contribute to human welfare. Cunninghamia lanceolata (Chinese fir) is an economically important conifer and occupies the largest area in China that produces global wood resources. Although Chinese fir has high economic value in China, little information is known regarding its mechanisms of wood formation. Therefore, transcriptome analysis was conducted to study the gene expression patterns and associated timber formation mechanisms in Chinese fir at different stand ages. In the present study, a total of 837,156 unigenes were identified in 84 samples from Chinese fir (pith and root) at different stand ages via RNA-Seq. Among them, most of the differentially expressed genes (DEGs) were significantly enrichment in plant hormone signal transduction, flavonoid metabolism pathway, starch and sucrose metabolism, and MAPK signal transduction pathway, which might be associated with the diameter formation in Chinese fir. The DEGs in these pathways were analyzed in Chinese fir and were related to lignin synthesis, cell wall formation and cell wall reinforcement/thickening. These genes might play an important role in regulating timber formation/growth in Chinese fir. In addition, certain transcriptome factors (TFs) related to Chinese fir timber formation were identified, including WRKY33, WRKY22, PYR/PYL, and MYC2. Weighted co-expression network analysis (WGCNA) showed that glucan endo-1,3-beta-d-glucosidase was a hub gene significantly correlated with the growth-related genes in Chinese fir. Sixteen key genes that related to diameter regulation in Chinese fir were verified by qRT-PCR analysis. These key genes might have a fine regulatory role in timber formation in Chinese fir. Our results pave the way for research on the regulatory mechanisms of wood formation, and provide an insight for improving the quality production of Chinese fir.

Overexpression of Bacterial Beta-Ketothiolase Improves Flax (Linum usitatissimum L.) Retting and Changes the Fibre Properties

Beta-ketothiolases are involved in the beta-oxidation of fatty acids and the metabolism of hormones, benzenoids, and hydroxybutyrate. The expression of bacterial beta-ketothiolase in flax (Linum usitatissimum L.) results in an increase in endogenous beta-ketothiolase mRNA levels and beta-hydroxybutyrate content. In the present work, the effect of overexpression of beta-ketothiolase on retting and stem and fibre composition of flax plants is presented. The content of the components was evaluated by high-performance liquid chromatography, gas chromatography–mass spectrometry, Fourier-transform infrared spectroscopy, and biochemical methods. Changes in the stem cell walls, especially in the lower lignin and pectin content, resulted in more efficient retting. The overexpression of beta-ketothiolase reduced the fatty acid and carotenoid contents in flax and affected the distribution of phenolic compounds between free and cell wall-bound components. The obtained fibres were characterized by a slightly lower content of phenolic compounds and changes in the composition of the cell wall. Based on the IR analysis, we concluded that the production of hydroxybutyrate reduced the cellulose crystallinity and led to the formation of shorter but more flexible cellulose chains, while not changing the content of the cell wall components. We speculate that the changes in chemical composition of the stems and fibres are the result of the regulatory properties of hydroxybutyrate. This provides us with a novel way to influence metabolic composition in agriculturally important crops.

A cell wall invertase modulates resistance to fusarium crown rot and sharp eyespot in common wheat

Fusarium crown rot (FCR) and sharp eyespot (SE) are serious soil-borne diseases in wheat and its relatives that have been reported to cause wheat yield losses in many areas. In this study, the expression of a cell wall invertase gene, TaCWI-B1, was identified to be associated with FCR resistance through a combination of bulk segregant RNA sequencing and genome resequencing in a recombinant inbred line population. Two bi-parental populations were developed to further verify TaCWI-B1 association with FCR resistance. Overexpression lines and ethyl methanesulfonate (EMS) mutants revealed TaCWI-B1 positively regulating FCR resistance. Determination of cell wall thickness and components showed that the TaCWI-B1-overexpression lines exhibited considerably increased thickness and pectin and cellulose contents. Furthermore, we found that TaCWI-B1 directly interacted with an alpha-galactosidase (TaGAL). EMS mutants showed that TaGAL negatively modulated FCR resistance. The expression of TaGAL is negatively correlated with TaCWI-B1 levels, thus may reduce mannan degradation in the cell wall, consequently leading to thickening of the cell wall. Additionally, TaCWI-B1-overexpression lines and TaGAL mutants showed higher resistance to SE; however, TaCWI-B1 mutants were more susceptible to SE than controls. This study provides insights into a FCR and SE resistance gene to combat soil-borne diseases in common wheat.