Salicylic acid fights against Fusarium wilt by inhibiting target of rapamycin signaling pathway in Fusarium oxysporum

Untargeted foodomics for authenticating the organic farming of water spinach (Ipomoea aquatica)

This study aimed to conduct a comprehensive analysis of the primary and secondary metabolites of water spinach (Ipomoea aquatica) using hydrophilic interaction liquid chromatography coupled with Orbitrap high-resolution mass spectrometry (HILIC-Orbitrap-HRMS). Certified samples from two cultivars, Green stem water spinach (G) and White stem water spinach (W) cultivated using organic and conventional farming methods, were collected from the Hong Kong market. Multivariate analysis was used to differentiate water spinach of different cultivars and farming methods. We identified 12 metabolites to distinguish between G and W, 26 metabolites to identify G from organic farming and 8 metabolites to identify W from organic farming. Then, two metabolites, isorhamnetin and jasmonic acid, have been proposed to serve as biomarkers for organic farming (in both G and W). Our foodomics findings provide useful tools for improving the crop performance of water spinach under abiotic/biotic stressesand authentication of organic produce.

Disruption of Cell Membranes and Redox Homeostasis as an Antibacterial Mechanism of Dielectric Barrier Discharge Plasma against Fusarium oxysporum

Direct barrier discharge (DBD) plasma is a potential antibacterial strategy for controlling Fusarium oxysporum (F. oxysporum) in the food industry. The aim of this study was to investigate the inhibitory effect and mechanism of action of DBD plasma on F. oxysporum. The result of the antibacterial effect curve shows that DBD plasma has a good inactivation effect on F. oxysporum. The DBD plasma treatment severely disrupted the cell membrane structure and resulted in the leakage of intracellular components. In addition, flow cytometry was used to observe intracellular reactive oxygen species (ROS) levels and mitochondrial membrane potential, and it was found that, after plasma treatment, intracellular ROS accumulation and mitochondrial damage were accompanied by a decrease in antioxidant enzyme activity. The results of free fatty acid metabolism indicate that the saturated fatty acid content increased and unsaturated fatty acid content decreased. Overall, the DBD plasma treatment led to the oxidation of unsaturated fatty acids, which altered the cell membrane fatty acid content, thereby inducing cell membrane damage. Meanwhile, DBD plasma-induced ROS penetrated the cell membrane and accumulated intracellularly, leading to the collapse of the antioxidant system and ultimately causing cell death. This study reveals the bactericidal effect and mechanism of the DBD treatment on F. oxysporum, which provides a possible strategy for the control of F. oxysporum.

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

BACKGROUND

Potatoes, a major economic crop, are significantly impacted by Fusarium dry rot, a prevalent postharvest disease. Despite the broad-spectrum antimicrobial properties of cinnamaldehyde, a naturally-derived plant substance, its efficacy against the causal pathogen of potato dry rot (Fusarium oxysporum) and the underlying mechanisms have not been extensively studied.

RESULTS

Our study demonstrates that cinnamaldehyde effectively inhibits the growth of Fusarium oxysporum, the pathogen responsible for potato dry rot, and increases its sensitivity to environmental stress factors such as extreme temperatures and high salt stress. Treatment with cinnamaldehyde results in altered fungal mycelium morphology, compromised cell wall stability, and disrupted cell membrane integrity, thereby reducing spore viability. Specifically, it interferes with the cell membrane and cell wall structures of the fungus, potentially disrupting fungal growth by modulating signaling pathways involved in cell wall maintenance, chitin metabolism, and GPI-anchored protein function. Notably, we show that cinnamaldehyde induces a form of regulated cell death in F. oxysporum, which is characterized not as typical apoptosis, as evidenced by Annexin V negative staining. However, the specific cell death type and underlying mechanism still needed to be further explored.

CONCLUSION

Cinnamaldehyde, an environmentally friendly plant-based active compound, exhibits strong inhibitory effects on F. oxysporum, indicating its potential use in the prevention and control strategies for potato dry rot. This research contributes to the understanding of novel antifungal mechanisms and offers promising insights into eco-friendly alternatives for managing this economically significant postharvest disease. © 2024 Society of Chemical Industry.

Antimicrobial Activities of Natural Bioactive Polyphenols

Secondary metabolites, polyphenols, are widespread in the entire kingdom of plants. They contain one or more hydroxyl groups that have a variety of biological functions in the natural environment. These uses include polyphenols in food, beauty products, dietary supplements, and medicinal products and have grown rapidly during the past 20 years. Antimicrobial polyphenols are described together with their sources, classes, and subclasses. Polyphenols are found in different sources, such as dark chocolate, olive oil, red wine, almonds, cashews, walnuts, berries, green tea, apples, artichokes, mushrooms, etc. Examples of benefits are antiallergic, antioxidant, anticancer agents, anti-inflammatory, antihypertensive, and antimicrobe properties. From these sources, different classes of polyphenols are helpful for the growth of internal functional systems of the human body, providing healthy fats, vitamins, and minerals, lowering the risk of cardiovascular diseases, improving brain health, and rebooting our cellular microbiome health by mitochondrial uncoupling. Among the various health benefits of polyphenols (curcumin, naringenin, quercetin, catechin, etc.) primarily different antimicrobial activities are discussed along with possible future applications. For polyphenols and antimicrobial agents to be proven safe, adverse health impacts must be substantiated by reliable scientific research as well as in vitro and in vivo clinical data. Future research may be influenced by this evaluation.

Decoding the molecular mechanism underlying salicylic acid (SA)-mediated plant immunity: an integrated overview from its biosynthesis to the mode of action

Salicylic acid (SA) is an important phytohormone, well-known for its regulatory role in shaping plant immune responses. In recent years, significant progress has been made in unravelling the molecular mechanisms underlying SA biosynthesis, perception, and downstream signalling cascades. Through the concerted efforts employing genetic, biochemical, and omics approaches, our understanding of SA-mediated defence responses has undergone remarkable expansion. In general, following SA biosynthesis through Avr effectors of the pathogens, newly synthesized SA undergoes various biochemical changes to achieve its active/inactive forms (e.g. methyl salicylate). The activated SA subsequently triggers signalling pathways associated with the perception of pathogen-derived signals, expression of defence genes, and induction of systemic acquired resistance (SAR) to tailor the intricate regulatory networks that coordinate plant immune responses. Nonetheless, the mechanistic understanding of SA-mediated plant immune regulation is currently limited because of its crosstalk with other signalling networks, which makes understanding this hormone signalling more challenging. This comprehensive review aims to provide an integrated overview of SA-mediated plant immunity, deriving current knowledge from diverse research outcomes. Through the integration of case studies, experimental evidence, and emerging trends, this review offers insights into the regulatory mechanisms governing SA-mediated immunity and signalling. Additionally, this review discusses the potential applications of SA-mediated defence strategies in crop improvement, disease management, and sustainable agricultural practices.

Inhibition of Potato Fusarium Wilt by Bacillus subtilis ZWZ-19 and Trichoderma asperellum PT-29: A Comparative Analysis of Non-Targeted Metabolomics

Potato Fusarium Wilt is a soil-borne fungal disease that can seriously harm potatoes throughout their growth period and occurs at different degrees in major potato-producing areas in China. To reduce the use of chemical agents and improve the effect of biocontrol agents, the inhibitory effects of the fermentation broth of Bacillus subtilis ZWZ-19 (B) and Trichoderma asperellum PT-29 (T) on Fusarium oxysporum were compared under single-culture and co-culture conditions. Furthermore, metabolomic analysis of the fermentation broths was conducted. The results showed that the inhibitory effect of the co-culture fermentation broth with an inoculation ratio of 1:1 (B1T1) was better than that of the separately cultured fermentation broths and had the best control effect in a potted experiment. Using LC-MS analysis, 134 metabolites were determined and classified into different types of amino acids. Furthermore, 10 metabolic pathways had the most significant variations, and 12 were related to amino acid metabolism in the KEGG analysis. A correlation analysis of the 79 differential metabolites generated through the comprehensive comparison between B, T, and B1T1 was conducted, and the results showed that highly abundant amino acids in B1T1 were correlated with amino acids in B, but not in T.

A review of chitosan nanoparticles: Nature's gift for transforming agriculture through smart and effective delivery mechanisms

Chitosan nanoparticles (CNPs) have emerged as a promising tool in agricultural advancements due to their unique properties including, biocompatability, biodegradability, non-toxicity and remarkable versatility. These inherent properties along with their antimicrobial, antioxidant and eliciting activities enable CNPs to play an important role in increasing agricultural productivity, enhancing nutrient absorption and improving pest management strategies. Furthermore, the nano-formulation of chitosan have the ability to encapsulate various agricultural amendments, enabling the controlled release of pesticides, fertilizers, plant growth promoters and biocontrol agents, thus offering precise and targeted delivery mechanisms for enhanced efficiency. This review provides a comprehensive analysis of the latest research and developments in the use of CNPs for enhancing agricultural practices through smart and effective delivery mechanisms. It discusses the synthesis methods, physicochemical properties, and their role in enhancing seed germination and plant growth, crop protection against biotic and abiotic stresses, improving soil quality and reducing the environmental pollution and delivery of agricultural amendments. Furthermore, the potential environmental benefits and future directions for integrating CNPs into sustainable agricultural systems are explored. This review aims to shed light on the transformative potential of chitosan nanoparticles as nature's gift for revolutionizing agriculture and fostering eco-friendly farming practices.

Editing Metabolism, Sex, and Microbiome: How Can We Help Poplar Resist Pathogens?

Poplar (Populus) is a genus of woody plants of great economic value. Due to the growing economic importance of poplar, there is a need to ensure its stable growth by increasing its resistance to pathogens. Genetic engineering can create organisms with improved traits faster than traditional methods, and with the development of CRISPR/Cas-based genome editing systems, scientists have a new highly effective tool for creating valuable genotypes. In this review, we summarize the latest research data on poplar diseases, the biology of their pathogens and how these plants resist pathogens. In the final section, we propose to plant male or mixed poplar populations; consider the genes of the MLO group, transcription factors of the WRKY and MYB families and defensive proteins BbChit1, LJAMP2, MsrA2 and PtDef as the most promising targets for genetic engineering; and also pay attention to the possibility of microbiome engineering.

Advancements in coating technologies: Unveiling the potential of chitosan for the preservation of fruits and vegetables

Post-harvest losses of fruits and vegetables pose a significant challenge to the agriculture industry worldwide. To address this issue, researchers have turned to natural and eco-friendly solutions such as chitosan coatings. Chitosan, a biopolymer derived from chitin, has gained considerable attention due to its unique properties such as non-toxicity, biodegradability, biocompatibility and potential applications in post-harvest preservation. This review article provides an in-depth analysis of the current state of research on chitosan coatings for the preservation of fruits and vegetables. Moreover, it highlights the advantages of using chitosan coatings, including its antimicrobial, antifungal, and antioxidant properties, as well as its ability to enhance shelf-life and maintain the quality attributes of fresh product. Furthermore, the review discusses the mechanisms by which chitosan interacts with fruits and vegetables, elucidating its antimicrobial activity, modified gas permeability, enhanced physical barrier and induction of host defense responses. It also examines the factors influencing the effectiveness of chitosan coatings, such as concentration, molecular weight, deacetylation degree, pH, temperature, and application methods.

Anti-Oomycete Effect and Mechanism of Salicylic Acid on Phytophthora infestans

Pathogenic oomycetes infect a wide variety of organisms, including plants, animals, and humans, and cause massive economic losses in global agriculture, aquaculture, and human health. Salicylic acid (SA), an endogenous phytohormone, is regarded as an inducer of plant immunity. Here, the potato late blight pathogen Phytophthora infestans was used as a model system to uncover the inhibitory mechanisms of SA on pathogenic oomycetes. In this research, SA significantly inhibited the mycelial growth, sporulation, sporangium germination, and virulence of P. infestans. Inhibition was closely related to enhanced autophagy, suppression of translation initiation, and ribosomal biogenesis in P. infestans, as shown by multiomics analysis (transcriptomics, proteomics, and phosphorylated proteomics). Monodansylcadaverine (MDC) staining and Western blotting analysis showed that SA promoted autophagy in P. infestans by probably targeting the TOR signaling pathway. These observations suggest that SA has the potential to control late blight caused by P. infestans.

Functional Analysis of a Salicylate Hydroxylase in Sclerotinia sclerotiorum

Salicylic acid plays a crucial role during plant defense to Sclerotinia sclerotiorum. Some bacteria and a few fungi can produce salicylate hydroxylase to degrade SA to suppress plant defense and increase their virulence. But there has been no single salicylate hydroxylase in Sclerotinia sclerotiorum identified until now. In this study, we found that SS1G_02963 (SsShy1), among several predicted salicylate hydroxylases in S. sclerotiorum, was induced approximately 17.6-fold during infection, suggesting its potential role in virulence. SsShy1 could catalyze the conversion of SA to catechol when heterologous expression in E. coli. Moreover, overexpression of SsShy1 in Arabidopsis thaliana decreased the SA concentration and the resistance to S. sclerotiorum, confirming that SsShy1 is a salicylate hydroxylase. Deletion mutants of SsShy1 (∆Ssshy1) showed slower growth, less sclerotia production, more sensitivity to exogenous SA, and lower virulence to Brassica napus. The complemented strain with a functional SsShy1 gene recovered the wild-type phenotype. These results indicate that SsShy1 plays an important role in growth and sclerotia production of S. sclerotiorum, as well as the ability to metabolize SA affects the virulence of S. sclerotiorum.

Highly Selective and Rapid "Turn-On" Fluorogenic Chemosensor for Detection of Salicylic Acid in Plants and Food Samples

Salicylic acid (SA) is one of the chemical molecules, involved in plant growth and immunity, thereby contributing to the control of pests and pathogens, and even applied in fruit and vegetable preservation. However, only a few tools have ever been designed or executed to understand the physiological processes induced by SA or its function in plant immunity and residue detection in food. Hence, three Rh6G-based fluorogenic chemosensors were synthesized to detect phytohormone SA based on the "OFF-ON" mechanism. The probes showed high selectivity, ultrafast response time (<60 s), and nanomolar detection limit for SA. Moreover, the probe possessed outstanding profiling that can be successfully used for SA imaging of callus and plants. Furthermore, the fluorescence pattern indicated that SA could occur in the distal transport in plants. These remarkable results contribute to improving our understanding of the multiple physiological and pathological processes involved in SA for plant disease diagnosis and for the development of immune activators. In addition, SA detection in some agricultural products used probes to extend the practical application because its use is prohibited in some countries and is harmful to SA-sensitized persons. Interestingly, the as-obtained test paper displayed that SA could be imaged by ultraviolet (UV) and was directly visible to the naked eye. Given the above outcomes, these probes could be used to monitor SA in vitro and in vivo, including, but not limited to, plant biology, food residue detection, and sewage detection.

Genome-wide association study to identify novel loci and genes for Fusarium root rot resistance in sweet potato using genotyping-by-sequencing

Fusarium root rot, caused by Fusarium solani, is a major post-harvest disease in sweet potatoes (Ipomoea batatas (L.) Lam.). An effective strategy for controlling this disease is the development of resistant varieties. In this study, a genome-wide association study (GWAS) was conducted on 96 sweet potato genotypes to identify novel candidate loci and dissect the genetic basis of Fusarium root rot resistance. Genotyping was performed using genotyping-by-sequencing (GBS), and 44,255 SNPs were identified after filtering. The genotypes (n = 96) were evaluated through resistance tests in 2021 and 2022, separately and combined. The GWAS identified two significant SNP markers (LG3_22903756 and LG4_2449919) on chromosomes 3 and 4 associated with Fusarium root rot resistance, respectively. Lesion length showed significant differences between homozygous A and G alleles of LG3_22903756, which can potentially be used to develop molecular markers for selecting accessions resistant to Fusarium root rot. Expression analysis of 11 putative genes flanking the significant SNPs revealed the alteration in the expression of nine genes, indicating their possible involvement in Fusarium root rot resistance. The results of this study will aid in the marker-assisted selection and functional analysis of candidate genes for Fusarium root rot resistance in sweet potatoes.

Pathogenicity, Mycotoxin Production, and Control of Potato Dry Rot Caused by Fusarium spp.: A Review

Fusarium dry rot is one of the major potato diseases during storage after harvest, which not only results in quality degradation but also causes great economic losses. The disease can be elicited by some species of Fusarium, and the pathogenic fungi of Fusarium causing potato dry rot are considerably diverse in various countries and regions. The disease caused by Fusarium spp. is associated with mycotoxins accumulation, which has phytotoxic and mycotoxic effects on humans and animals. Chemical synthetic fungicide is considered the main control measure for the Fusarium dry rot of potato; nevertheless, it is unfortunate that persistent application inevitably results in the emergency of a resistant strain and environmental contamination. A comprehensive disease control strategy includes potato cultivar selection, appropriate cultural practices (crop rotation, cultivate pattern, fertilization, and irrigation), harvesting processes and postharvest treatments (harvesting, classification, packaging, wound healing), and storage conditions (environmental disinfection, temperature, humidity and gas composition) along with the application of fungicide pre-harvest or post-harvest. Recently, emerging studies have indicated that eco-friendly strategies include physical control, chemical methods (such as the application of generally-recognised-as-safe (GRAS) compounds or chemical (elicitors) and biological control have been introduced to combat the Fusarium dry rot of potato.

MicroRNAs involved in the trans-kingdom gene regulation in the interaction of maize kernels and Fusarium verticillioides

Maize ear rot is a widespread disease and the main pathogen is Fusarium verticillioides. Plant microRNAs (miRNAs) have great effects on disease resistance and it has been reported that maize miRNA participates in defense responses in maize ear rot. However, the trans-kingdom regulation of miRNAs between maize and F. verticillioides remains uncharacterized. In this study, the relationship between miRNA-like RNAs (milRNAs) of F. verticillioides and pathogenicity was investigated, followed by sRNA analysis and degradome sequencing of miRNA profiles and the target genes of maize and F. verticillioides after inoculation. It was found that the milRNA biogenesis positively regulated the pathogenicity of F. verticillioides by knocking out the gene FvDicer2-encoded Dicer-like protein in F. verticillioides. Following inoculation with F. verticillioides, 284 known and 6571 novel miRNAs were obtained in maize, including 28 miRNAs differentially expressed at multiple time points. The target genes of maize differentially expressed miRNAs in F. verticillioides mediated multiple pathways, including autophagy and MAPK signaling pathway. Fifty-one novel F. verticillioides milRNAs were predicted to target 333 genes in maize involved in MAPK signaling pathways, plant hormone signaling transduction and plant-pathogen interaction pathways. Additionally, the miR528b-5p in maize targeted the mRNA of FvTTP which encoded a twice transmembrane protein in F. verticillioides. The FvTTP-knockout mutants displayed decreased pathogenicity and reduced synthesis of fumonisins. Thus, by interfering with the translation of FvTTP, the miR528b-5p inhibited F. verticillioides infection. These findings suggested a novel function of miR528 in resisting F. verticillioides infection. The miRNAs identified in this research and their putative target genes can be used to further elucidate the trans-kingdom functions of microRNAs in plant pathogen interaction.

Changes in polyamine contents during Fusarium graminearum and Fusarium verticillioides inoculation in maize seedlings with or without seed-priming

Maize (Zea mays L.) is the most produced field crop all over the world. One of its most critical diseases that results in economic loss is ear rot caused by various Fusarium species. Previous researches have shown that polyamines, found in all living cells, play crucial role in biotic stress responses. At the same time, biosynthesis of polyamines is of paramount importance not only for plants but also for their pathogens to promote stress tolerance and pathogenicity. In our study, we investigated the polyamine content changes induced in the seedlings of two maize genotypes of different susceptibility by isolates of Fusarium verticillioides and Fusarium graminearum, two Fusarium species of different lifestyles. Apart from that, it was examined how infection efficiency and changes in polyamine contents were modified by salicylic acid or putrescine seed soaking pre-treatments. Our observations confirmed that initial and stress-induced changes in the polyamine contents are not directly related to tolerance in either coleoptile or radicle. However, the two pathogens with different lifestyles induced remarkably distinct changes in the polyamine contents. The effect of the seed soaking pre-treatments depended on the pathogens and plant resistance as well: both salicylic acid and putrescine seed soaking had positive results against F. verticillioides, while in the case of infection with F. graminearum, seed soaking with distilled water alone affected biomass parameters positively in the tolerant genotype.

TORC1 Signaling in Fungi: From Yeasts to Filamentous Fungi

Target of rapamycin complex 1 (TORC1) is an important regulator of various signaling pathways. It can control cell growth and development by integrating multiple signals from amino acids, glucose, phosphate, growth factors, pressure, oxidation, and so on. In recent years, it has been reported that TORC1 is of great significance in regulating cytotoxicity, morphology, protein synthesis and degradation, nutrient absorption, and metabolism. In this review, we mainly discuss the upstream and downstream signaling pathways of TORC1 to reveal its role in fungi.

Identification of Wheat LACCASEs in Response to Fusarium graminearum as Potential Deoxynivalenol Trappers

Fusarium graminearum (F. graminearum) can cause huge yield reductions and contamination of grain with deoxynivalenol (DON), and thus is one of the most problematic pathogen of wheat worldwide. Although great efforts have been paid and great achievements have been made to control the pathogens, there is still a wide gap for understanding the mechanism underlying F. graminearum resistance. Plant LACCASEs (LACs) catalyze the oxidative polymerization of monolignols by reinforcing cell-wall of various cell types to provide mechanical support, xylem sap transportation, and defense against pest and pathogens. To date, little has been known about LAC genes in bread wheat and their potential roles in wheat-F. graminearum interaction. Through systematic analysis of the genome-wide homologs and transcriptomes of wheat, a total of 95 Triticum aestivum laccases (TaLACs) were identified, and 14 of them were responsive to F. graminearum challenge. 3D structure modelings of the 14 TaLAC proteins showed that only TaLAC78 contains the entire activity center for oxidation and the others lack the type 1 copper ion ligand (T1Cu). Both amino acid sequence alignment and three-dimensional reconstruction after amino acid mutation showed that the loss of T1Cu is not only related to variation of the key amino acid coordinating T1Cu, but also closely related to the flanking amino acids. Significantly differential temporal expression patterns of TaLACs suggested that their subfunctionalization might occur. Promoter array analysis indicated that the induction of TaLACs may be closely associated with salicylic acid signaling, dehydration, and low-oxygen stress under F. graminearum infection. Molecular docking simulation demonstrated that TaLACs can not only catalyze lignin as a substrate, but also interact with DON, which may be docked into the binding position of the monolignols, where the LACs recognize substrates. The current study provides clues for exploring the novel functions of TaLACs in wheat resistance to F. graminearum, and TaLACs maybe candidates for conferring a high level of resistance against F. graminearum in wheat.