Phytopathogenic Microorganisms Research Articles

Novel 5-Sulfonyl-1,3,4-thiadiazole-Substituted Flavonoids as Potential Bactericides and Fungicides: Design, Synthesis, Three-Dimensional Quantitative Structure-Activity Relationship Studies.

Flavonoids, ubiquitous natural products, provide sources for drug discovery owing to their structural diversity, broad-spectrum pharmacological activity, and excellent environmental compatibility. To develop antibacterial and antifungal agents with novel mechanisms of action and innovative structures, a series of novel 5-sulfonyl-1,3,4-thiadiazole-substituted flavonoids were designed and synthesized, and their biological activities against seven agriculturally common phytopathogenic microorganisms were evaluated. The results of the antimicrobial bioassay showed that most of the target compounds displayed excellent inhibitory effects against Xanthomonas oryzae, Rhizoctonia solani, and Colletotrichum orbiculare. Compounds 1, 3, 7, 9, 13, and 14 exhibited remarkable antibacterial activity against X. oryzae pv. oryzae with EC50 values below 10 μg/mL, which were superior to bismerthiazol (70.89 μg/mL). Compound 2 (EC50 = 0.41 μg/mL) displayed the most effective inhibitory potency against R. solani in vivo, comparable protective effects with the positive control carbendizam. Preliminary mechanistic studies indicated that compound 2 induced disordered entanglement of hyphae, shrinkage of hyphal surfaces, extravasation of cellular contents, and vacuole swelling and rupture, which disrupted normal hyphal growth. Subsequently, compounds 35-53 with good antifungal activity were designed and synthesized based on reliable three-dimensional quantitative structure-activity relationship (3D-QSAR) models. Compound 49 showed high efficacy and superior antifungal activity against R. solani, with an EC50 value of 0.28 μg/mL and a half-maximal effective concentration of 0.46 μg/mL.

Deciphering bacterial community structure in Cola lepidota (K.) Schum fruits using Illumina next-generation sequencing

Cola lepidota cultivation is hampered by pathogenic microorganisms which affect the quality and quantity of produce after harvest. Bacterial organisms cause softening of tissues which may lead to the spoilage of the whole fruit. This study aimed to detect the bacterial organisms and the bacterial community structure associated with monkey cola (Cola lepidota K. Schum) fruits using Illumina next-generation sequencing (NGS). Amplification of the v4 regions of the 16S rDNA gene was performed through Polymerase chain reaction (PCR) using the primers, 515F and 806R. Picking of the Operational Taxonomic Units (OTUs) and assignment of the OTUs into different taxonomic levels were performed on GREENGENES database. The most abundant phyla obtained from Cola lepidota mesocarp and seeds were Proteobacteria (40.83 %), Bacteroidetes (31.01 %) and Firmicutes (24.52 %). The abundance of Bacteroides, which was the predominant genus in the majority of the samples, was between 31 and 72 % among the total bacteria identified in most samples. Other relatively high abundant genera obtained across the total bacterial community of C. lepidota were Pseudomonas (19.20 %), Tepidimonas (13.76 %) and Acinetobacter (13.33 %). We obtained potentially beneficial, human and phytopathogenic microorganisms which play important roles in evolutionary and ecological processes. Among these genera include Acinetobacter and Staphylococcus which are opportunistic human pathogens. This study revealed the bacterial organisms associated with monkey cola fruits and indicates that Illumina next generation sequencing can be used to determine the bacterial community structure and bacterial organisms in fruits.

A review on endophytic fungi: a potent reservoir of bioactive metabolites with special emphasis on blight disease management.

Phytopathogenic microorganisms have caused blight diseases that present significant challenges to global agriculture. These diseases result in substantial crop losses and have a significant economic impact. Due to the limitations of conventional chemical treatments in effectively and sustainably managing these diseases, there is an increasing interest in exploring alternative and environmentally friendly approaches for disease control. Using endophytic fungi as biocontrol agents has become a promising strategy in recent years. Endophytic fungi live inside plant tissues, forming mutually beneficial relationships, and have been discovered to produce a wide range of bioactive metabolites. These metabolites demonstrate significant potential for fighting blight diseases and provide a plentiful source of new biopesticides. In this review, we delve into the potential of endophytic fungi as a means of biocontrol against blight diseases. We specifically highlight their significance as a source of biologically active compounds. The review explores different mechanisms used by endophytic fungi to suppress phytopathogens. These mechanisms include competing for nutrients, producing antifungal compounds, and triggering plant defense responses. Furthermore, this review discusses the challenges of using endophytic fungi as biocontrol agents in commercial applications. It emphasizes the importance of conducting thorough research to enhance their effectiveness and stability in real-world environments. Therefore, bioactive metabolites from endophytic fungi have considerable potential for sustainable and eco-friendly blight disease control. Additional research on endophytes and their metabolites will promote biotechnology solutions.

PHYSICOCHEMICAL, PHYTOCHEMICAL, SPECTROSCOPIC (LCMS, AND H1-NMR) ANALYSIS OF EXTRACTS OF PLUMBAGO ZEYLANICA

Objective: This study aimed to find the physicochemical, phytochemical analysis, and spectroscopic analysis of solvent extracts of the roots of Plumbago zeylanica. Methods: The Soxhlet apparatus was employed to extract individual solvent extracts from the roots of P. zeylanica. In this study, solvent extracts made from the roots of P. zeylanica are tested for their physicochemical properties, phytochemical make-up, and spectroscopic properties. Spectroscopic investigations were conducted with the Bruker 400 MHz nuclear magnetic resonance (NMR) system, manufactured in Switzerland, as well as liquid chromatography mass spectroscopy (LC-MS), a mass spectrometer. Results: The physicochemical study of P. zeylanica roots revealed a moisture content of 10.51%, a total ash content of 2.06%, and an alcohol-soluble extract of 1.72%. In addition, many physical parameters such as color, taste, aroma, and nature were examined. The phytochemical analysis of P. zeylanica revealed the detection of significant phytonutrients, including tannins, carbohydrates, proteins, flavonoids, alkaloids, and sterols, in the root sample. The presence of tannins, carbohydrates, proteins, flavonoids, alkaloids, and sterols in extracts of P. zeylanica was established through spectroscopic analysis using H1-NMR and LCMS. Conclusion: The examination of solvent extracts obtained from the roots of P. zeylanica involved physicochemical, phytochemical, and spectroscopic techniques. This research revealed the presence of many biologically active metabolites, including alkaloids, amino acids, flavonoids, phenols, tannins, and terpenoids. The identification of these metabolites presents a promising prospect for substituting conventional chemical methods in the management of clinically pathogenic and phytopathogenic microorganisms.

Streptomyces Strains and Their Metabolites for Biocontrol of Phytopathogens in Agriculture.

Sustainable agriculture is increasingly linked to biological pesticides as alternatives to agro-chemicals. Streptomyces species suppress plant diseases through their unique traits and numerous metabolites. Although many Streptomyces strains have been developed into commercial products, their roles in the biocontrol of phytopathogens and mechanisms of functional metabolite synthesis remain poorly understood. In this review, biocontrol of plant diseases by Streptomyces is summarized on the basis of classification of fungal and bacterial diseases and secondary metabolites produced by Streptomyces that act on phytopathogenic microorganisms are discussed. The associated non-ribosomal peptide synthetases and polyketide synthetases responsible for biosynthesis of these secondary metabolites are also investigated, and advances in fermentation of Streptomyces are described. Finally, the need to develop precise and effective biocontrol methods for plant diseases is highlighted.

Формування фітопатогенного мікобіому на вегетативних органах рослин пшениці озимої

Cultivated plants, which are characterized by high resistance to phytopathogenic microorganisms, create significant selective pressure on their populations and select highly pathogenic and aggressive forms. Highly susceptible plants to such microorganisms ensure a rapid growth in the population of phytopathogenic micromycetes in agrocenoses. Cultivation of such plant groups on production crops leads to an increase in biological pollution of the agrosphere and a significant decrease in the level of biological safety. This requires increased use of chemical means of plant protection against diseases, which causes chemical pollution of agroecosystems and leads to a significant decrease in the quality of plant products through the accumulation of metabolic products of phytopathogenic microorganisms in it and a decrease in biological safety in agrocenoses. Therefore, the assessment and selection of winter wheat varieties as a factor in the regulation of the phytopathogenic mycobiome in agrocenoses is a highly relevant area of research that ensures the selection of ecologically safe varieties of cultivated plants. Cultivation of such varieties leads to a decrease in the level of biological pollution in agrocenoses and increases the quality and safety of plant products. It is known that biotic, abiotic and anthropogenic factors affect the formation of populations of microorganisms. Therefore, the formation of the mycobiome on the vegetative organs of winter wheat during the ontogenesis of plants under traditional and organic technologies was investigated. It has been proven that the meteorological conditions during the years of the study, namely: high air temperature and a significant amount of precipitation during the growing season, which was observed in 2021 and in the long dry years of 2020 and 2022, had a significant impact on the formation of the population of micromycetes in the agrocenosis of winter wheat. According to the results of our own research, the population density of micromycetes and the intensity of sporulation of mushroom species decreased during the phase of emergence into the tube using traditional cultivation technology. At the same time, during the earing phase, mushroom sporulation increases by 2–3 times. This can be explained by the homeostatic reaction of the population of micromycetes in the mycobiome of vegetative organs of winter wheat plants to the chemical pressure of applied pesticides, which can cause contamination of agrocenoses with infectious structures of pathogens and their toxic metabolites. At the same time, the population density of micromycetes, under organic cultivation technology, increased during the growing season from the tillering phase to the earing phase, depending on the soil and climatic conditions. Under the conditions of various winter wheat cultivation technologies, significant changes in the formation of micromycete populations were observed due to the influence of varietal characteristics of plants. A significantly lower frequency of occurrence of species and their intensity of sporulation was observed on the vegetative organs of the Skagen variety, compared to winter wheat plants of the Podolyanka variety. This testifies to the ability of physiological and biochemical substances of plants of various varieties of winter wheat to stimulate or restrain the development of micromycetes in the mycobiome of vegetative organs of the culture. Evaluation of the plant variety based on indicators of influence on the density, frequency of occurrence and intensity of sporulation of micromycetes will ensure a decrease in the level of biological pollution and an increase in the biosafety of plant raw materials.

Development and synthesis of compounds with fungicidal activity in suppression of fungal growth

The research was conducted to synthesize and study fungicidal activity of synthesized chemical compounds of various classes, triazole and imidazole, and their mode of action due to the wide spectrum of action and low application rates. The developed synthesis methods resulted in several groups of nitrogen-containing heterocyclic compounds and evaluated their fungicidal activity. Inhibitory activity of compounds to strains of Fusarium solani (medium resistance to fungicides) and Sclerotinia sclerotiorum (susceptible to most fungicides) from the collection of phytopathogenic microorganisms of Agrobiotechnological Department, RUDN University, was tested. In the synthesis of new chemical compounds with fungicidal activity, urea derivatives 1-(3-(Difluoromethyl)-1-methyl-1H-pyrazole-5-yl)-3-(2-chlorophenyl) urea were identified and structurally confirmed. All target compounds were evaluated for their antifungal activity to inhibit mycelium growth. Preliminary screening results showed that all synthesized compounds have good fungicidal activity against S. sclerotiorum . The compound 1-(3-(Difluoromethyl)-1-methyl-1H-pyrazole-5-yl)-3-(3-fluorophenyl) urea showed antifungal activity against S. sclerotiorum . At concentration of 100 ppm, the compound suppressed growth of S. sclerotiorum strain by 90.5 %. An in vitro experiment revealed that the compound 1-(3-(Difluoromethyl)1-methyl-1H-pyrazole-5-yl)-3-(3-fluorophenyl) urea was effective for suppressing white mold - S . sclerotiorum , at the dose of 100 mg/L. The significance of the research lies in the fact that production of eco-safe products in agroindustry is impossible without development of new biologically active compounds with low application rates and toxicity indicators, controlled persistence, corresponding to the world level. The results obtained can be implemented in real sector of economy engaged in production of chemical plant protection products. Synthesis and use of new fungicides are relevant in agricultural production as an element of development and intensification of existing agricultural technologies.

Phytochemical Profiling, Antioxidant, and Antifungal Activities of Ethyl Acetate and Chloroformic Extracts from Three Mentha Species

Background Phytopathogenic fungi remain the main infectious agents in plants, causing severe damage to the environment and human health. Thus, to reduce the usage of synthetically derived fungicides and perform agricultural crop production, the search for new control strategies including plant extracts constitutes an eco-friendly and safe alternative. Objectives This study aimed to quantify the phytochemical constituents of the three plant ( Mentha pulegium L., Mentha spicata L., and Mentha longifolia L.) extracts and to screen their phytochemical composition including total phenolic (TPC), flavonoids (TFC) and condensed tannins contents (TCTC), and to evaluate their antioxidant activities. The efficacy of all mint extracts will be investigated against phytopathogenic fungal species. Materials and Methods The three plant extracts were screened to assess their total phenolic, flavonoids, and condensed tannin contents using spectrophotometric assays. The antioxidant activities include 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP), and β-carotene assays. The antifungal activities were investigated on phytopathogenic species including Botrytis cinerea, Fusarium culmorum, Fusarium oxysporum, Aspergillus niger, Aspergillus flavus, and Trichoderma sp. Results Quantitative analyses of phytochemical constituents of Mentha genus extracts revealed that both ethyl acetate (EtAc) and chloroformic (Chl) extracts are a rich source of phenols, flavonoids, and condensed tannins. Ethyl acetate extract of M. longifolia (EtAc L) displayed the highest content of phenols (69.9 ± 1.35 mg GAE/g DW) and flavonoids (53.26 ± 2.11 mg CE/g DW), while M. pulegium ethyl acetate extract (EtAc P) has the highest condensed tannins content (2.13 ± 0.4 mg CE/g DW). Moreover, the tested extracts exhibited potent antioxidant activities at low concentrations for EtAc L, followed by M. spicata (EtAc S), and EtAc P (IC50 = 35.76 ± 1.32 µg/mL for scavenging DPPH free radicals; EC50 527.96 ± 5.45 µg/mL for FRAP, and IC50 = 106.3 ± 3.75 µg/mL for β-carotene bleaching test). Finally, all tested extracts were able to inhibit the growth of several phytopathogenic micro-organisms on both agar and broth media. Conclusion The Mentha extracts derived from the three mint species (i.e., L, P, and S) could be used for their antifungal activities to provide sustainable crop pest management.

The Fungus Beauveria bassiana Alters Amounts of Sterols, Fatty Acids, and Hydroxycinnamic Acids in Potato Solanum tuberosum

The entomopathogenic endophytic fungus Beauveria bassiana can colonize plants resulting in growth promotion and protection against phytopathogenic microorganisms. However, physiological changes in potato plants (Solanum tuberosum) during this interaction are poorly understood. In the present work, gas chromatography–mass spectrometry and high-performance liquid chromatography were used to analyze sterol, fatty acid, and phenolic acid concentrations in potato plants inoculated with B. bassiana conidia in soil. We showed an increase in amounts of stigmasterol, minor sterol compounds, and some hydroxy fatty acids in leaves after the fungal treatment. Moreover, levels of hydroxycinnamic acids, especially chlorogenic acid, were elevated in roots following the B. bassiana inoculation. We propose that these changes could have been caused by oxidative reactions, and the alterations may have resulted in growth-stimulatory and protective effects of B. bassiana on the plants.

Emergence and growth of huacle chili seedlings (Capsicum annuum L.) with the use of biological formulations in commercial plot soil.

Objective: To evaluate the effect of biological control agents (BCA) and two biological formulations (Bio-Terra and Bio-CNPR) against the phytopathogens found in the soil of huacle chili (Capsicum annuum) plantations, in order to obtain healthy seedlings. Design/Methodology/Approach: The following design variables were evaluated: germination (%), disease incidence (%), and survival (%). Stem height and root length were also evaluated. The experimental unit was a tray with n=30 seedlings per each treatments (T0, T1, T2, T3, and T4) and four repetitions. An analysis of variance (ANOVA) was used. Tukey’s mean test was applied (using the Minitab Statistical program version 20.0) in units that presented differences (p≤0.05). Results: The phytopathogenic microorganism Fusarium spp. was isolated from the soil of the plots cultivated with huacle chili. The T1 treatment recorded the best inhibitory effect against Fusarium spp.: it had 92.2% germination, 18.3% incidence of Fusarium spp., and 82% surviving seedlings (with an average height of 16 cm and a root length of 7.9 cm). The sterilization of the soil lead to T4 having the best results in germination, incidence, and survival, since Fusarium spp. did not damage huacle chili seedlings. In contrast, T0 did not prosper neither with BCA nor with biological products, since all the seedlings in non-sterile soil died. Study Limitations/Implications: A plastic barrier was placed between the trays with the chili seedlings to avoid cross-contamination between treatments. Findings/Conclusions: T1 (the BCA with nitrogen-fixing bacteria and B. subtilis) recorded the best counteracting results against the damage generated by Fusarium spp. Their antagonism allowed a high percentage of survival of huacle chili seedlings and encouraged plant development through the best root growth and height of the seedlings.

A Comprehensive Review on Euphorbiaceae lectins: Structural and Biological Perspectives.

Euphorbiaceae, also known as the spurge family, is a large group of flowering plants. Despite being tropical natives, they are now widespread. Due to its medicinal and commercial importance, this family of plants attracted a lot of attention in the scientific community. The distinctive characteristic of the family is production of milky latex, which is a rich source of several lectins, the proteins that bind carbohydrates. Although their function is unclear, they are believed to defend plants against damaging phytopathogenic microorganisms, insects, and predatory animals. Additionally, they serve as crucial metabolic regulators under a variety of stressors. Detection, separation, purification, and characterization of lectins from the Euphorbiaceae family - mostly from the latex of plants - began over 40 years ago. This effort produced over 35 original research papers that were published. However, no systematic review that compiles these published data has been presented yet. This review summarizes and describes several procedures and protocols employed for extraction and purification of lectins belonging to this family. Physicochemical properties and biological activities of the lectins, along with their medicinal and pharmacological properties, have also been analyzed. Additionally, using examples of ricin and ricin agglutinin, we have structurally analyzed characteristics of the lectin known as Ribosome Inactivating Protein Type II (RIP-Type II) that belongs to this family. We anticipate that this review article will offer a useful compendium of information on this important family of lectins, show the scientists involved in lectin research the gaps in our knowledge, and offer insights for future research.

ANTIMICROBIAL ACTIVITY OF SOIL BACILLI AGAINST PHYTOPATHOGENIC MICROORGANISMS ISOLATED FROM AFFECTED CEREAL PLANTS

Aim of this study was to investigate the antagonistic effect of bacilli isolated from the surface of plants and the rhizosphere zone of the soil against pathogens of barley and wheat diseases. Materials and methods. The material for the study was affected barley and wheat samples used to isolate phytopathogenic microorganisms, as well as samples of healthy plants and the rhizosphere soil zone used to isolate bacteria of the genus Bacillus. Manipulations for the isolation and investigation the biological properties of both phytopathogens and bacilli were carried out by traditional microbiological methods. The antagonistic activity of the isolated strains of bacilli against phytopathogens was studied by the block method. Results. From samples of affected wheat and barley were isolated microorganisms identified on the basis of the studied biological properties as Fusarium oxysporum, Sclerotinia sclerotiorum, Xanthomonas arboricola and Pectobacterium carotovorum. The largest proportion of strains was represented by the micromycete Fusarium oxysporum – 53.9%. From samples of the rhizosphere soil zone and leaf-stem mass of healthy wheat and barley plants, 86 strains of bacteria of the genus Bacillus were isolated by microbiological methods. Antagonistic activity was inherent in 54 strains of bacilli against 25% of phytopathogens. All pathogenic microorganisms were inhibited with different intensity by 14 strains of bacilli. Conclusion. The most active bacillus strains (Bacillus spp. 6, 9, 13, 21, 50) were selected for further research.

Five Different Artemisia L. Species Ethanol Extracts' Phytochemical Composition and Their Antimicrobial and Nematocide Activity.

Among the plants that exhibit significant or established pharmacological activity, the genus Artemisia L. deserves special attention. This genus comprises over 500 species belonging to the largest Asteraceae family. Our study aimed at providing a comprehensive evaluation of the phytochemical composition of the ethanol extracts of five different Artemisia L. species (collected from the southwest of the Russian Federation) and their antimicrobial and nematocide activity as follows: A. annua cv. Novichok., A. dracunculus cv. Smaragd, A. santonica cv. Citral, A. abrotanum cv. Euxin, and A. scoparia cv. Tavrida. The study of the ethanol extracts of the five different Artemisia L. species using the methods of gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-MS/MS) allowed establishing their phytochemical profile. The obtained data on the of five different Artemisia L. species ethanol extracts' phytochemical composition were used to predict the antibacterial and antifungal activity against phytopathogenic microorganisms and nematocidal activity against the free-living soil nematode Caenorhabditis elegans. The major compounds found in the composition of the Artemisia L. ethanol extracts were monoterpenes, sesquiterpenes, flavonoids, flavonoid glycosides, coumarins, and phenolic acids. The antibacterial and antifungal activity of the extracts began to manifest at a concentration of 150 µg/mL. The A. dracunculus cv. Smaragd extract had a selective effect against Gram-positive R. iranicus and B. subtilis bacteria, whereas the A. scoparia cv. Tavrida extract had a selective effect against Gram-negative A. tumefaciens and X. arboricola bacteria and A. solani, R. solani and F. graminearum fungi. The A. annua cv. Novichok, A. dracunculus cv. Smaragd, and A. santonica cv. Citral extracts in the concentration range of 31.3-1000 µg/mL caused the death of nematodes. It was established that A. annua cv. Novichok affects the UNC-63 protein, the molecular target of which is the nicotine receptor of the N-subtype.

Programmed cell death in Xanthomonas axonopodis pv. glycines is associated with modulation of gene expression resulting in altered states of motility, biofilm and virulence

One of the foremost report of apoptosis-like programmed cell death (PCD) came from Xanthomonas axonopodis pv. glycines (Xag), which displayed rapid post-exponential cell death in PCD inducing media (PIM) but not in a non-inducing media (PNIM). The current study aims to decipher for the first time, the advantages of the existence of PCD in this phytopathogenic microorganism. Analysis of RNA-seq under inducing and non-inducing conditions, revealed differential expression of a number of genes related to key physiology of Xag, such as, motility, xanthan biosynthesis and export as well as virulence. A PCD negative mutant Xag M42 displayed diminished virulence and a contrasting transcriptome pattern. In vitro experiments revealed that under PCD inducing condition, Xag produced negligible xanthan gum as well as extracellular amylase, displayed enhanced swarming motility, released copious e-DNA and formed scanty biofilm. Lack of ‘diffusible signalling factor’ production was eliminated as possible reason for PCD-induction. Altogether, it appears that, in planta existence of the pathogen metabolically resembles PNIM, and on being transferred to PIM, the cells experience oxidative stress and circumvents it by adopting PCD as an altruistic response. Survival of the remaining population is encouraged by upregulating motility, detachment from the fragile biofilm to achieve dispersal.

Properties of actinomycetes from the rhizosphere of Colobanthus quitensis (Kunth) Bartl. (Booth Island, maritime Antarctica)

Aim. Investigate the biological properties of actinomycetes from the rhizosphere of Colobanthus quitensis (Kunth) Bartl. and study their ability to produce bioactive compounds. Methods. Microbiological (isolation, synthesis of bioactive compounds), genetic and genetic engineering (isolation and analysis of total DNA, DNA gel electrophoresis, polymerase chain reaction, DNA sequencing), bioinformatic (phylogenetic analysis) methods. Results. 21 actinomycete isolates were obtained from the samples of C. quitensis rhizosphere. Half of the isolates exhibited antagonistic properties towards at least one of 17 test cultures of pathogenic and phytopathogenic microorganisms. Some strains exhibited both antibacterial and antifungal activities. The majority of isolates (70-95 %) produced proteases, amylases, cellulases, almost 42 % – nitrate reductases, 20-25 % – pectinases and lipases, respectively. Conclusions. A collection of Antarctic actinomycetes has been created and characterized, which is promising for evaluating their metabolic potential as producers of antibiotics.

A Switch from Latent to Typical Infection during Pectobacterium atrosepticum-Tobacco Interactions: Predicted and True Molecular Players.

Phytopathogenic microorganisms, being able to cause plant diseases, usually interact with hosts asymptomatically, resulting in the development of latent infections. Knowledge of the mechanisms that trigger a switch from latent to typical, symptomatic infection is of great importance from the perspectives of both fundamental science and disease management. No studies to date have compared, at the systemic molecular level, the physiological portraits of plants when different infection types (typical and latent) are developed. The only phytopathogenic bacterium for which latent infections were not only widely described but also at least fluently characterized at the molecular level is Pectobacterium atrosepticum (Pba). The present study aimed at the comparison of plant transcriptome responses during typical and latent infections caused by Pba in order to identify and then experimentally verify the key molecular players that act as switchers, turning peaceful plant-Pba coexistence into a typical infection. Based on RNA-Seq, we predicted plant cell wall-, secondary metabolism-, and phytohormone-related genes whose products contributed to the development of the disease or provided asymptomatic plant-Pba interactions. By treatment tests, we confirmed that a switch from latent to typical Pba-caused infection is determined by the plant susceptible responses mediated by the joint action of ethylene and jasmonates.

Functional characterization and structural basis of a reversible glycosyltransferase involves in plant chemical defence.

Plants experience numerous biotic stresses throughout their lifespan, such as pathogens and pests, which can substantially affect crop production. In response, plants have evolved various metabolites that help them withstand these stresses. Here, we show that two specialized metabolites in the herbaceous perennial Belamcanda chinensis, tectorigenin and its glycoside tectoridin, have diverse defensive effects against phytopathogenic microorganisms and antifeeding effects against insect pest. We further functionally characterized a 7-O-uridine diphosphate glycosyltransferase Bc7OUGT, which catalyses a novel reversible glycosylation of tectorigenin and tectoridin. To elucidate the catalytic mechanisms of Bc7OUGT, we solved its crystal structure in complex with UDP and UDP/tectorigenin respectively. Structural analysis revealed the Bc7OUGT possesses a narrow but novel substrate-binding pocket made up by plentiful aromatic residues. Further structure-guided mutagenesis of these residues increased both glycosylation and deglycosylation activities. The catalytic reversibility of Bc7OUGT was also successfully applied in an one-pot aglycon exchange reaction. Our findings demonstrated the promising biopesticide activity of tectorigenin and its glycosides, and the characterization and mechanistic study of Bc7OUGT could facilitate the design of novel reversible UGTs to produce valuable glycosides with health benefits for both plants and humans.

Phytochemical Properties of Silk Floss Tree Stem Bark Extract and Its Potential as an Eco-Friendly Biocontrol Agent against Potato Phytopathogenic Microorganisms

In the current study, the ethanolic extract of the stem bark of Ceiba speciosa, the silk floss tree (SFSB), was evaluated against various phytopathogenic microorganisms, including Ralstonia solanacearum, Dickeya solani, Pectobacterium atrosepticum, P. carotovorum, Fusarium oxysporum, and Rhizoctonia solani. At 300 µg/mL concentration, the SFSB extract exhibited the highest inhibition percentages of 83.33 and 86.67 for R. solani and F. oxysporum, respectively. In addition to its antimicrobial activity, SFSB extract exhibited strong antioxidant activity (IC50 value of 140.88 g/mL). HPLC analysis of the extract revealed the presence of various phenolic acids and flavonoids. Among these compounds, naringenin (18,698.83 µg/g), chlorogenic acid (2727.49 µg/g), ferulic acid (1276.18 µg/g), syringic acid (946.26 µg/g), gallic acid (812.34 µg/g), and methyl gallate (651.73 µg/g) were found to be the most abundant constituents. GCMS analysis showed that there were antimicrobial compounds like terpenoids, benzoic acid derivatives, phthalate esters, and different fatty acids. Isopropyl myristate was the most common compound, with a relative abundance of 55.61%. To our knowledge, this is the first investigation on the phytochemical composition and antimicrobial properties of SFSB extract. Consequently, utilizing SFSB extract could hold significant potential as a sustainable and natural approach for controlling and mitigating plant diseases.

Selenium nanoparticles based on Amphipterygium glaucum extract with antibacterial, antioxidant, and plant biostimulant properties

BackgroundIn recent years, crop production has expanded due to the variety of commercially available species. This increase in production has led to global competition and the search for biostimulant products that improve crop quality and yield. At the same time, agricultural products that protect against diseases caused by phytopathogenic microorganisms are needed. Thus, the green synthesis of selenium nanoparticles (SeNPs) is a proposal for achieving these needs. In this research, SeNPs were synthesized from methanolic extract of Amphipterygium glaucum leaves, and chemically and biologically characterized.ResultsThe characterization of SeNPs was conducted by ultraviolet–visible spectrophotometry (UV–Vis), scanning electron microscopy (SEM), electron microscopy transmission (TEM), Dynamic Light Scattering (DLS), energy dispersion X-ray spectroscopy (EDX), and infrared spectrophotometry (FTIR) techniques. SeNPs with an average size of 40–60 nm and spherical and needle-shaped morphologies were obtained. The antibacterial activity of SeNPs against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis was evaluated. The results indicate that the methanolic extracts of A. glaucum and SeNPs presented a high antioxidant activity. The biostimulant effect of SeNPs (10, 20, 50, and 100 µM) was evaluated in vinca (Catharanthus roseus), and calendula (Calendula officinalis) plants under greenhouse conditions, and they improved growth parameters such as the height, the fresh and dry weight of roots, stems, and leaves; and the number of flowers of vinca and calendula.ConclusionsThe antibacterial, antioxidant, and biostimulant properties of SeNPs synthesized from A. glaucum extract demonstrated in this study support their use as a promising tool in crop production.Graphical

Experimental substantiation of the method for assessing the phytotoxicity of micromycetes on wheat seedlings

Relevance. Currently, the relevance of studying to identify the ability of many micromycetes to synthesize phytotoxic substances that reduce seed germination and lead to huge losses in the yield of strategic agricultural crops is increasing. To solve the problem, the development of new methodological approaches is required, which is significant for immunologists and phytopathologists.The purpose of this work is to determine the phytotoxic activity of micromycete strains from the genera Fusarium, Alternaria, Bipolaris, parasitizing on all agricultural crops cultivated in Russia.Materials and methods. The strains, the methods of their cultivation, the bioassay method were used, and the statistical processing of the results obtained was carried out. A modification of some methodological approaches for assessing the phytotoxicity of micromycetes has been carried out. The selection of representative concentrations of culture fluid filtrates (FCF) of strains for phytotoxicity evaluation was carried out.Results. A correlation was established for all variants of the experiment between two independent parameters: the development parameters of wheat seedlings and the concentration of cultural liquid filtrates. New results have been obtained on the study of the phytotoxic activity of 70 strains of hemibiotrophic micromycetes and the optimal concentrations of fungal FAs for classifying fungal strains into toxicity groups have been established. The most variable toxicity values were found when using a 40% solution of FCL. It was shown that, under these conditions, fungal strains can be divided according to the degree of toxicity into significantly different groups. This circumstance is an important reason for including strains of micromycetes with certain toxicity properties in the State Collection of Phytopathogenic Microorganisms. Fungal strains are necessary and appropriate for use in breeding to create resistant and tolerant varieties to phytopathogens from the genera Fusarium, Alternaria, Bipolaris.Conclusion. New methodological approaches have confirmed that the most variable toxicity values were found with the use of FCF in a ratio of 2:3. This concentration of FCF strains are divided into 4 groups with characteristic differences in the degree of toxicity, which is an important reason for including such strains of micromycetes in the State Collection of Phytopathogenic Microorganisms and will be further used in breeding to create resistant and tolerant varieties of agricultural crops.