Infectious Plant Diseases: Etiology, Current Status, Problems and Prospects in Plant Protection

High-frequency shoot regeneration, assessment of genetic fidelity, and histochemical analysis of forskolin production in Coleus forskohlii Briq

Forskolin, a diterpenoid found in the roots of Coleus forskohlii, has generated significant interest in the medical field due to its various therapeutic uses. This study aimed to establish an effective system for regenerating C. forskohlii plants, ensuring a year-round supply of plant material and forskolin production. We tested different concentrations of cytokinins, either alone or combined with auxin, to see their impact on shoot multiplication and growth. We found that a medium supplemented with 1.5 mg L-1 of meta-topolin (mT) resulted in the highest number of shoots (~ 12.66) and leaves (~ 20) within about 5 days. When mT (1 mg L-1) was combined with a low amount of auxin (0.05 mg L-1 NAA), we obtained an even greater number of leaves (~ 23). The shoot regeneration capacity was consistent over five subculture passages, showing minimal variation in mean shoot length and number. During acclimatization, around 91% of the plantlets grown in vermiculite + sand survived. The photosynthetic pigment concentration in the plantlets modestly increased in the first 10 days and reached its highest level after 30 days. Genetic fidelity assays using inter simple sequence repeats (ISSRs) confirmed the similarity between the in vitro derived plantlets and the mother plant. Micro-morphological features of in vitro and ex-vitro acclimated plantlets also matched those of the mother plant, further confirming genetic accuracy. Histochemical staining with vanillin confirmed the presence of forskolin in the in vitro roots, indicated by the violet coloration in the cells. Forskolin quantification was also validated by HPLC where in vitro derived roots were documented to undergo an almost ~ 1.8-fold in comparison to that of the mother plant. This established protocol can effectively address resource scarcity for commercial-scale forskolin production and sustainable conservation techniques.

Impact of various intercropping modes on soil quality, microbial communities, yield and quality of Platycodon grandiflorum (Jacq.) A. DC

INTRODUCTION

Intercropping has the function of promoting plant growth, improving yield and quality. Platycodon grandiflorus (P. grandiflorus) is a traditional Chinese medicinal herb; continuous cropping obstacles significantly inhibit its yield and quality. However, few study have established about P. grandiflorus interaction of various crops. This study provides a theoretical foundation to explore the most effective intercropping method, enhance soil utilization efficiency, and increase the yield and quality of P. grandiflorus. We conducted field experiment, P. grandiflorus monoculture (JG-JG), P. grandiflorus and Achyranthes bidentata intercropping (JG-NX), P. grandiflorus and Saposhnikovia divaricata intercropping (JG-FF), P. grandiflorus and Glehnia littoralis (JG-SS) intercropping. Additionally, we included three main intercropping crops with P. grandiflorus, Zea mays (JG-YM), Setaria italica (JG-GZ), and Glycine max (JG-DD). The soil physicochemical properties, enzyme activity, soil microorganisms, the yield and secondary metabolite content in the roots of P. grandiflorus were determined. The results showed that intercropping significantly increased the yield and quality of P. grandiflorus, and significantly reduced the incidence rate of root rot. The intercropping system enhances the physical and chemical properties of soil, soil enzyme activity, and soil microbial diversity. JG-SS intercropping significantly increased the abundance of bacteria and fungi, stimulated soil microbial communities, promoted plant growth, significantly increased yield and content of platycodin D, enhanced the complexity of microbial co-occurrence networks. This study could provide a sustainable planting system for the cultivation of P. grandiflorus, particularly the system JG-SS.

CLINICAL TRIAL NUMBER

Not applicable.

An overview of the antifungal potential for aromatic plant extracts in agriculture and the food industry: A comprehensive analysis focusing on the Rubus, Cistus and Quercus genera against fungal infections of crops and food

This review article provides an overview of current research on aromatic plant extracts, particularly from the genera Rubus, Cistus and Quercus. These plants are characterized by their abundance in certain ecosystems such as dehesa, their robustness and adaptability to the environment, but despite their abundance in these regions, they remain relatively underutilized. In this review, the chemical profiles of plant extracts from these genera, the methodologies used for extraction of bioactive compounds and antifungal capabilities of are thoroughly investigated. Plants from Rubus, Cistus and Quercus genera are known for their richness in bioactive constituents, including terpenoids, flavonoids and phenols, which exhibit notable antifungal activities against various pathogenic fungi. Furthermore, the article explores future directions for the development and utilization of these extracts in agricultural and food sectors, underscoring their potential as natural and sustainable substitutes for synthetic fungicides. This comprehensive analysis explores the potential role of aromatic plant extracts in contributing to crop health, food safety, and environmentally sustainable agricultural practices, while recognizing the need for further research to fully substantiate their applications in these areas. The utilization of these plants not only aids in the preservation and promotion of biodiversity and environmental sustainability but also has the potential to create new products and markets, thereby providing economic benefits to the ecosystems where they are cultivated.

Unlocking the potential of ecofriendly guardians for biological control of plant diseases, crop protection and production in sustainable agriculture

Several beneficial microbial strains inhibit the growth of different phytopathogens and commercialized worldwide as biocontrol agents (BCAs) for plant disease management. These BCAs employ different strategies for growth inhibition of pathogens, which includes production of antibiotics, siderophores, lytic enzymes, bacteriocins, hydrogen cyanide, volatile organic compounds, biosurfactants and induction of systemic resistance. The efficacy of antagonistic strains could be further improved through genetic engineering for better disease suppression in sustainable farming practices. Some antagonistic microbial strains also possess plant-growth-promoting activities and their inoculation improved plant growth in addition to disease suppression. This review discusses the characterization of antagonistic microbes and their antimicrobial metabolites, and the application of these BCAs for disease control. The present review also provides a comprehensive summary of the genetic organization and regulation of the biosynthesis of different antimicrobial metabolites in antagonistic strains. Use of molecular engineering to improve production of metabolites in BCAs and their efficacy in disease control is also discussed. The application of these biopesticides will reduce use of conventional pesticides in disease control and help in achieving sustainable and eco-friendly agricultural systems.

Nanotechnology for controlling mango malformation: a promising approach

Mango (Mangifera indica L.) is one of the most important fruit crops in the world with yields of approximately 40 million tons annually and its production continues to decrease every year as a result of the attack of certain pathogens i.e. Colletotrichum gloeosporioides, Erythricium salmonicolor, Amritodus atkinsoni, Idioscopus clypealis, Idioscopus nitidulus, Bactrocera obliqua, Bactrocera frauenfeldi, Xanthomonas campestris, and Fusarium mangiferae. So F. mangiferae is the most harmful pathogen that causes mango malformation disease in mango which decreases its 90% yield. Nanotechnology is an eco-friendly and has a promising effect over traditional methods to cure fungal diseases. Different nanoparticles possess antifungal potential in terms of controlling the fungal diseases in plants but applications of nanotechnology in plant disease managements is minimal. The main focus of this review is to highlight the previous and current strategies to control mango malformation and highlights the promising applications of nanomaterials in combating mango malformation. Hence, the present review aims to provide brief information on the disease and effective management strategies.

An Efficient Model for Leafy Vegetable Disease Detection and Segmentation Based on Few-Shot Learning Framework and Prototype Attention Mechanism

This study proposes a model for leafy vegetable disease detection and segmentation based on a few-shot learning framework and a prototype attention mechanism, with the aim of addressing the challenges of complex backgrounds and few-shot problems. Experimental results show that the proposed method performs excellently in both object detection and semantic segmentation tasks. In the object detection task, the model achieves a precision of 0.93, recall of 0.90, accuracy of 0.91, mAP@50 of 0.91, and mAP@75 of 0.90. In the semantic segmentation task, the precision is 0.95, recall is 0.92, accuracy is 0.93, mAP@50 is 0.92, and mAP@75 is 0.92. These results show that the proposed method significantly outperforms the traditional methods, such as YOLOv10 and TinySegformer, validating the advantages of the prototype attention mechanism in enhancing model robustness and fine-grained feature expression. Furthermore, the prototype loss function, which optimizes the distance relationship between samples and category prototypes, significantly improves the model's ability to discriminate between categories. The proposed method shows great potential in agricultural disease detection, particularly in scenarios with few samples and complex backgrounds, offering broad application prospects.

Microbiome Analysis of Area in Proximity to White Spot Lesions Reveals More Harmful Plant Pathogens in Maize

Plant microbiomes play a major role in plant health, growth, and development, enhancing resistance to pathogen invasion. However, despite the extensive research on the phyllosphere microbiome, it remains unclear how the microbiome of leaves in proximity to diseased leaves responds to pathogen invasion. We investigate the response of the maize phyllosphere microbiome to maize white spot by assessing the microbiome dynamics associated with the white spot portion and the area in proximity using 16S and ITS high-throughput sequencing analysis. Our results showed that the bacterial diversities were higher in the diseased portion and area in proximity to the spot than those in healthy plants. At the same time, lower fungal diversity was recorded in the diseased portion compared to portions in proximity to it and healthy leaves. The spot portion had a significant influence on the microbial composition. The diseased portion, the area in proximity to it, and the healthy leaves were dominated by the bacterial genera Sphingomonas, Delftia, Chryseobacterium, Stenotrophomonas, Methylobacterium-methylorubrum, and Bacteroides. Still, the abundance of Sphingomonas decreased in the healthy leaves with a corresponding increase in Stenotrophomonas. Conversely, the fungal genus Setophoma dominated the diseased portion, while the fungal pathogens Cladosporium, Alternaria, and Exserohilum were highly abundant in the samples from the area in proximity to it. In addition, a co-occurrence network analysis revealed a complex fungal network in healthy leaves and those in proximity to leaves infected with white spot compared to the diseased portion. This study suggests that the area in proximity to the maize leaf infected with white spot disease is colonized by more harmful plant pathogenic fungi for disease progression.

Unveiling exogenous potential of phytohormones as sustainable arsenals against plant pathogens: molecular signaling and crosstalk insights

Plants frequently confront pathogens that disrupt physiological and molecular functions, ultimately reducing agricultural yields. To counter these challenges, plants activate sophisticated defense mechanisms to recognize stress signals while optimizing growth. Phytohormones signaling pathways and their crosstalk are central to regulating plant growth, development and defense. Numerous proteins associated with phytohormone signaling pathways have been identified, including receptors for several vital hormones. Previous studies indicate that defense phytohormones, like salicylic acid (SA), jasmonic acid (JA) and ethylene (ET), are crucial to pathogen defense. SA specifically mediates systemic acquired resistance against biotrophic pathogens, while induced systemic resistance relies on JA and ET signaling in response to necrotrophic pathogens. Other hormones, typically associated with growth and development, such as ethylene, abscisic acid, brassinosteroids, melatonin, gibberellins, auxin, and cytokinin, also interact in a complex network of synergistic and antagonistic relationships with defense phytohormones. Moreover, they can achieve effects that surpass conventional pathogen control methods, suggesting their potential as exogenous biocontrol agents. During the past decade, our knowledge of hormone signaling and stress response has become immense. Thus, this review is an attempt to summarize some of the advances in plant signaling and crosstalk mechanisms as well as their potential to be a future arsenal in biotic stress mitigation strategies. Ultimately, this work emphasizes using exogenous phytohormones as a viable alternative for controlling pathogens to enhance crop productivity in pathogen-affected regions.

Gatifloxacin hydrochloride confers broad-spectrum antibacterial activity against phytopathogenic bacteria

Bacterial diseases pose significant threats to agriculture and natural ecosystems, causing substantial crop losses and impacting food security. Until now, there has been a less efficient control strategy against some bacterial diseases such as bacterial wilt, caused by Ralstonia solanacearum. In this study, we screened a library of 58 microorganism-derived natural products for their antibacterial activity against R. solanacearum. Gatifloxacin hydrochloride exhibited the best inhibitory effect with an inhibition rate of 95% at 0.0625 mg/L. Further experiments demonstrate that gatifloxacin hydrochloride inhibits R. solanacearum growth in a concentration-dependent manner, with the minimum inhibitory concentration of 0.125 mg/L. Treatment with 0.5 mg/L of gatifloxacin hydrochloride killed more than 95% of bacteria. Gatifloxacin hydrochloride significantly inhibited biofilm formation by R. solanacearum. Gatifloxacin hydrochloride also shows good antibacterial activity against Pseudomonas syringae pv. tomato DC3000 and Xanthomonas campestris pv. vesicatoria. Exogenous application of gatifloxacin hydrochloride suppressed disease development caused by R. solanacearum and P. syringae. In summary, our results demonstrate the great potential of microorganism-derived compounds as broad-spectrum antibacterial compounds, providing alternative ways for the efficient control of bacterial plant diseases.

Citrus psyllid management by collective involvement of plant resistance, natural enemies and entomopathogenic fungi

Crops face constant threats from insect pests, which can lead to sudden disasters and global famine. One of the most dangerous pests is the Asian citrus psyllid (ACP), which poses a significant threat to citrus plantations worldwide. Effective and adaptive management strategies to combat ACP are always in demand. Plant resistance (PR) is a key element in pest management, playing crucial roles such as deterring pests through antifeedant and repellant properties, while also attracting natural enemies of these pests. One effective and innovative approach is the use of entomopathogenic fungi (EPF) to reduce pest populations. Additionally, other natural enemies play an important role in controlling certain insect pests. Given the significance of PR, EPF, and natural arthropod enemies (NAE), this review highlights the benefits of these strategies against ACP, drawing on successful examples from recent research. Furthermore, we discuss how EPF can be effectively utilized in citrus orchards, proposing strategies to ensure its efficient use and safeguard food security in the future.

Dynamic responses of soil microbial communities to seasonal freeze-thaw cycles in a temperate agroecosystem

Soil freeze-thaw cycles (FTCs) are common in temperate agricultural ecosystems during the non-growing season and are progressively influenced by climate change. The impact of these cycles on soil microbial communities, crucial for ecosystem functioning, varies under different agricultural management practices. Here, we investigated the dynamic changes in soil microbial communities in a Mollisol during seasonal FTCs and examined the effects of stover mulching and nitrogen fertilization. We revealed distinct responses between bacterial and fungal communities. The dominant bacterial phyla reacted differently to FTCs: for example, Proteobacteria responded opportunistically, Actinobacteria, Acidobacteria, Choroflexi and Gemmatimonadetes responded sensitively, and Saccharibacteria exhibited a tolerance response. In contrast, the fungal community composition remained relatively stable during FTCs, except for a decline in Glomeromycota. Certain bacterial OTUs acted as sensitive indicators of FTCs, forming keystone modules in the network that are closely linked to soil carbon, nitrogen content and potential functions. Additionally, neither stover mulching nor nitrogen fertilization significantly influenced microbial richness, diversity and potential functions. However, over time, more indicator species specific to these agricultural practices began to emerge within the networks and gradually occupied the central positions. Furthermore, our findings suggest that farming practices, by introducing keystone microbes and changing interspecies interactions (even without changing microbial richness and diversity), can enhance microbial community stability against FTC disturbances. Specifically, higher nitrogen input with stover removal promotes fungal stability during soil freezing, while lower nitrogen levels increase bacterial stability during soil thawing. Considering the fungal tolerance to FTCs, we recommend reducing nitrogen input for manipulating bacterial interactions, thereby enhancing overall microbial resilience to seasonal FTCs. In summary, our research reveals that microbial responses to seasonal FTCs are reshaped through land management to support ecosystem functions under environmental stress amid climate change.

Catalase-associated immune responses in plant-microbe interactions: A review

Catalase, an enzyme central to maintaining redox balance and combating oxidative stress in plants, has emerged as a key player in plant defense mechanisms and interactions with microbes. This review article provides a comprehensive analysis of catalase-associated immune responses in plant-microbe interactions. It underscores the importance of catalase in plant defense mechanisms, highlights its influence on plant susceptibility to pathogens, and discusses its implications for understanding plant immunity and host-microbe dynamics. This review contributes to the growing body of knowledge on catalase-mediated immune responses and offers insights that can aid in the development of strategies for improved plant health and disease resistance.

Friends and Foes: Bacteria of the Hydroponic Plant Microbiome

Hydroponic greenhouses and vertical farms provide an alternative crop production strategy in regions that experience low temperatures, suboptimal sunlight, or inadequate soil quality. However, hydroponic systems are soilless and, therefore, have vastly different bacterial microbiota than plants grown in soil. This review highlights some of the most prevalent plant growth-promoting bacteria (PGPB) and destructive phytopathogenic bacteria that dominate hydroponic systems. A complete understanding of which bacteria increase hydroponic crop yields and ways to mitigate crop loss from disease are critical to advancing microbiome research. The section focussing on plant growth-promoting bacteria highlights putative biological pathways for growth promotion and evidence of increased crop productivity in hydroponic systems by these organisms. Seven genera are examined in detail, including Pseudomonas, Bacillus, Azospirillum, Azotobacter, Rhizobium, Paenibacillus, and Paraburkholderia. In contrast, the review of hydroponic phytopathogens explores the mechanisms of disease, studies of disease incidence in greenhouse crops, and disease control strategies. Economically relevant diseases caused by Xanthomonas, Erwinia, Agrobacterium, Ralstonia, Clavibacter, Pectobacterium, and Pseudomonas are discussed. The conditions that make Pseudomonas both a friend and a foe, depending on the species, environment, and gene expression, provide insights into the complexity of plant-bacterial interactions. By amalgamating information on both beneficial and pathogenic bacteria in hydroponics, researchers and greenhouse growers can be better informed on how bacteria impact modern crop production systems.

First Investigation of Secondary Metabolites from Aspergillus xerophilus Reveals Compounds with Inhibitive Effects against Three Phytopathogenic Fungi of Agrarian Crops

Fungal secondary metabolites play a highly significant role in crop protection, which is related to their antifungal activity against agriculturally important phytopathogens. In fact, plant diseases caused by fungi including species belonging to the genera of Alternaria, Botrytis, and Fusarium have become increasingly serious affecting crop yield and quality. Hence, there is increasing awareness by the scientific community of the importance of exploiting fungal products for finding new compounds able to inhibit phytopathogens. In this study several drimane-type sesquiterpenes have been detected for the first time as products of Aspergillus xerophilus by GC-MS analysis of the organic extracts obtained from the mycelia and culture filtrates of the fungus grown on two different substrates. Seven pure drimane-type sesquiterpenes were also isolated and identified by spectroscopic methods. The inhibitory effects of the pure compounds have been investigated against three phytopathogenic fungi of agrarian crops (i.e., Botrytis cinerea, Alternaria alternata, and Fusarium oxysporum f. sp. pisi). Among the drimane-type sesquiterpenes isolated in this study, 9,11-dihydroxy-6-oxodrim-7-ene is the most active against the three phytopathogens. Our findings also reveal the high sensitivity of A. alternata to the isolated compounds. These results pave the way for future applications in agriculture of both A. xerophilus and its metabolites.

Combining Thermotherapy with Shoot Tip Culture or Cryotherapy for Improved Virus Eradication from In Vitro Actinidia macrosperma

In recent years, kiwifruit viral diseases have become increasingly prevalent in kiwifruit-producing regions of China, significantly impacting both the yield and quality of kiwifruit. This has emerged as a significant constraint on the healthy and sustainable development of the kiwifruit industry. The use of virus-free propagation materials has been proven the most effective strategy for controlling plant viral diseases. In the present study, shoot tip culture, shoot tip cryotherapy, and their combinations with thermotherapy were established to eradicate Actinidia virus A (AcVA), Actinidia virus B (AcVB), and Actinidia chlorotic ringspot-associated virus (AcCRaV) from Actinidia macrosperma. Additionally, the impact of shoot tip size on virus eradication was evaluated. Among the three confirmed viruses, regardless of the procedure, AcVB was the easiest to eradicate, followed by AcVA and AcCRaV. Combining thermotherapy with shoot tip culture or cryotherapy resulted in a higher virus-free frequency (up to 27.3 and 50%, respectively) than shoot tip culture or cryotherapy alone (0 to 20%). Notably, the combination of thermotherapy and 0.5- to 1-mm shoot tip cryotherapy was shown to be the most effective protocol for virus eradication from A. macrosperma, which produced 50% of regenerated shoots free from all the tested viruses. To the best of our knowledge, this is the first report on virus elimination from kiwifruit infected with multiple viruses based on conventional shoot tip culture and shoot tip cryotherapy.

A review on the encapsulation of "eco-friendly" compounds in natural polymer-based nanoparticles as next generation nano-agrochemicals for sustainable agriculture and crop management

Crop management techniques and sustainable agriculture offer a comprehensive farming method that incorporates social, economic, and ecological factors. Sustainable agriculture places a high priority on soil health, water efficiency, and biodiversity conservation in order to develop resilient and regenerative food systems that can feed both the current and future generations. Our goal in this review is to give a thorough overview of current developments in the use of polysaccharides as raw materials for the encapsulation of natural chemicals in nanoparticles as novel crop protection products. The search for recent research articles and latest reviews has been carried out through pubmed, google scholar, BASE as search engines. Offer cutting-edge solutions for sustainable crop management that satisfy the demands of an expanding population, comply with changing legal frameworks, and address environmental issues by encasing natural compounds inside polysaccharide-based nanoparticles. A variety of natural substances, such as essential oils, plant extracts, antimicrobials compounds and miRNA, can be included in these nanoparticles. These materials have many advantages, such as biocompatibility, biodegradability and controlled release of active compounds. Thanks to their action mechanism, they are able to mediate hormone signaling and gene expression in different plant physiological aspects, as well as enhance their tolerance to abiotic stress conditions. Sustainable agriculture can be supported by this type of treatments, correctly developing food safety through the production of non-toxic nanoparticles, low-cost industrial scale-up and the use of biodegradable materials. Polysaccharide-based nanoparticles have a wide range of uses in agriculture: they improve crop yields, encourage "eco-friendly" farming methods and can decrease the concentrations of active ingredient used, providing an accurate and affective dosage without damaging further species, as well as avoiding treatment resistance risks. These nanoparticles can also reduce the negative effects of chemical fertilizers and pesticides, contributing to the environmentally friendly agricultural development. Furthermore, the application of polysaccharide-based nanoparticles is consistent with the expanding trend of green and sustainable agriculture.

Harnessing bacterial endophytes for environmental resilience and agricultural sustainability

In the current era of environmental disasters and the necessity of sustainable development, bacterial endophytes have gotten attention for their role in improving agricultural productivity and ecological sustainability. This review explores the multifaceted contributions of bacterial endophytes to plant health and ecosystem sustainability. Bacterial endophytes are invaluable sources of bioactive compounds, promising breakthroughs in medicine and biotechnology. They also serve as natural biocontrol agents, reducing the need for synthetic fertilizers and fostering environmentally friendly agricultural practices. It provides eco-friendly solutions that align with the necessity of sustainability since they can improve pest management, increase crop resilience, and facilitate agricultural production. This review also underscores bacterial endophytes' contribution to promoting sustainable and green industrial productions. It also presented how incorporating these microorganisms into diverse industrial sectors can harmonize humankind with ecological stability. The potential of bacterial endophytes has been largely untapped, presenting an opportunity for pioneering advancements in sustainable industrial applications. Their importance caught attention as they provided innovative solutions to the challenging problems of the new era. This review sheds light on the remarkable potential of bacterial endophytes in various industrial sectors. Further research is imperative to discover their multifaceted potential. It will be essential to delve deeper into their mechanisms, broaden their uses, and examine their long-term impacts.

Early diagnosis of Cladosporium fulvum in greenhouse tomato plants based on visible/near-infrared (VIS/NIR) and near-infrared (NIR) data fusion

Plant diseases can inflict varying degrees of damage on agricultural production. Therefore, identifying a rapid, non-destructive early diagnostic method is crucial for safeguarding plants. Cladosporium fulvum (C. fulvum) is one of the major diseases in tomato growth. This work presents a method of data fusion using two hyperspectral imaging systems of visible/near-infrared (VIS/NIR) and near-infrared (NIR) spectroscopy for the early diagnosis of C. fulvum in greenhouse tomatoes. First, hyperspectral images of samples at health and different times of infection were collected. The average spectral data of the image regions of interest were extracted and preprocessed for subsequent spectral datasets. Then different classification models were established for VIS/NIR and NIR data, optimized through various variable selection and data fusion methods. The principal component analysis-radial basis function neural network (PCA-RBF) model established using low-level data fusion achieved optimal results, achieving accuracies of 100% and 99.3% for calibration and prediction, respectively. Moreover, both the macro-averaged F1 (Macro-F1) values reached 1, and the geometric mean (G-mean) values reached 1 and 1, respectively. The results indicated that it was feasible to establish a PCA-RBF model by using the hyperspectral technique with low-level data fusion for the early detection of C. fulvum in greenhouse tomatoes.

Advancements in Green Nanoparticle Technology: Focusing on the Treatment of Clinical Phytopathogens

Opportunistic pathogenic microbial infections pose a significant danger to human health, which forces people to use riskier, more expensive, and less effective drugs compared to traditional treatments. These may be attributed to several factors, such as overusing antibiotics in medicine and lack of sanitization in hospital settings. In this context, researchers are looking for new options to combat this worrying condition and find a solution. Nanoparticles are currently being utilized in the pharmaceutical sector; however, there is a persistent worry regarding their potential danger to human health due to the usage of toxic chemicals, which makes the utilization of nanoparticles highly hazardous to eukaryotic cells. Multiple nanoparticle-based techniques are now being developed, offering essential understanding regarding the synthesis of components that play a crucial role in producing anti-microbial nanotherapeutic pharmaceuticals. In this regard, green nanoparticles are considered less hazardous than other forms, providing potential options for avoiding the extensive harm to the human microbiome that is prevalent with existing procedures. This review article aims to comprehensively assess the current state of knowledge on green nanoparticles related to antibiotic activity as well as their potential to assist antibiotics in treating opportunistic clinical phytopathogenic illnesses.

Total Synthesis of Conjugation-Ready Hyperbranched Pentasaccharide of Clavibacter phaseoli VKM Ac-2641T by [Au]/[Ag] Catalysis

Infections by Clavibacter spp. cause an economic burden to farmers. The components present in the cell wall glycopolymers (CWGs) are important for studying the host-pathogen interactions, colonization, and infection. A pentasaccharide containing a hyperbranched Ribf-, Galf-, and Manp- has recently been identified. Herein, we describe the first total synthesis of the conjugation-ready hyperbranched pentasaccharide of C. phaseoli VKM Ac-2641T using the [Au]/[Ag]-catalyzed glycosidation chemistry of ethynylcyclohexyl carbonate glycosyl donors. The pentasaccharide was synthesized in a highly convergent fashion from readily accessible monosaccharide building blocks.

Green Routes: Exploring Protein-Based Virus-like Nanoparticle Transport and Immune Activation in Nicotiana benthamiana for Biotechnological Applications

Viral, bacterial, fungal, and nematode infections cause significant agricultural losses, with limited treatment options, necessitating novel approaches to enhance plant defense systems and protection against pathogens. Virus-like nanoparticles (VLPs), extensively used in animal and human therapies (e.g., vaccines and immune enhancers), hold potential for novel agricultural solutions and advancing plant nanotechnology. This study employed various methodologies, including VLP production, confocal microscopy, and real-time qPCR. Our findings demonstrated the presence of 30 nm Qβ-VLPs, fluorescently labeled, within the intercellular space of Nicotiana benthamiana leaves one hour post-infiltration. Furthermore, infiltration with Qβ-VLPs led to an upregulation of key defense genes (NbPR1a, NbPR5, NbNPR, NbERF1, NbMYC2, and NbLRR2) in treated plants. Using RT-qPCR, a significant increase in the relative expression levels of defense genes was observed, with sustained high levels of NbERF1 and NbLRR2 even after 24 h. These findings suggest that Qβ-VLPs effectively upregulate genes crucial for pathogen defense in N. benthamiana, initiating PAMP-triggered immunity and launching signaling cascades that enhance defense mechanisms. This innovative application of VLPs to activate plant defense programs advances plant nanobiotechnology, offering new agricultural solutions.

Recent advances in biosensors for screening plant pathogens

Worldwide, plant pathogens have been a considerably important cause of economic loss in agriculture especially in the decades of agricultural intensification. The increasing losses in agriculture due to biotic plant diseases have drawn attention towards the development of plant disease analyzing methods. In this context, biosensors have emerged as significantly important tools which help farmers in on-field diagnosis of plant diseases. Compared to traditional methods, biosensors have outstanding features such as being highly sensitive and selective, cost-effective, portable, fast and user-friendly operation, and so on. There are three common types of biosensors including electrochemical, fluorescent, and colorimetric biosensors. In this review, some common biotic plant diseases caused by fungi, bacteria, and viruses are first summarized. Then, current advances in developing biosensors are discussed.

An updated view of bacterial endophytes as antimicrobial agents against plant and human pathogens

Bacterial endophytes are a crucial component of the phytomicrobiome, playing an essential role in agriculture and industries. Endophytes are a rich source of bioactive compounds, serving as natural antibiotics that can be effective in combating antibiotic resistance in pathogens. These bacteria interact with host plants through various processes such as quorum sensing, chemotaxis, antibiosis, and enzymatic activity. The current paper focuses on how plants benefit extensively from endophytic bacteria and their symbiotic relationship in which the microbes enhance plant growth, nitrogen fixation, increase nutrient uptake, improve defense mechanisms, and act as antimicrobial agents against pathogens. Moreover, it highlights some of the bioactive compounds produced by endophytes.

Antifungal Activity of Ribosome-Inactivating Proteins

The control of crop diseases caused by fungi remains a major problem and there is a need to find effective fungicides that are environmentally friendly. Plants are an excellent source for this purpose because they have developed defense mechanisms to cope with fungal infections. Among the plant proteins that play a role in defense are ribosome-inactivating proteins (RIPs), enzymes obtained mainly from angiosperms that, in addition to inactivating ribosomes, have been studied as antiviral, fungicidal, and insecticidal proteins. In this review, we summarize and discuss the potential use of RIPs (and other proteins with similar activity) as antifungal agents, with special emphasis on RIP/fungus specificity, possible mechanisms of antifungal action, and the use of RIP genes to obtain fungus-resistant transgenic plants. It also highlights the fact that these proteins also have antiviral and insecticidal activity, which makes them very versatile tools for crop protection.

Nanotechnology in agriculture: A solution to global food insecurity in a changing climate?

Although the Green Revolution dramatically increased food production, it led to non- sustainable conventional agricultural practices, with productivity in general declining over the last few decades. Maintaining food security with a world population exceeding 9 billion in 2050, a changing climate, and declining arable land will be exceptionally challenging. In fact, nothing short of a revolution in how we grow, distribute, store, and consume food is needed. In the last ten years, the field of nanotoxicology in plant systems has largely transitioned to one of sustainable nano-enabled applications, with recent discoveries on the use of this advanced technology in agriculture showing tremendous promise. The range of applications is quite extensive, including direct application of nanoscale nutrients for improved plant health, nutrient biofortification, increased photosynthetic output, and greater rates of nitrogen fixation. Other applications include nano-facilitated delivery of both fertilizers and pesticides; nano-enabled delivery of genetic material for gene silencing against viral pathogens and insect pests; and nanoscale sensors to support precision agriculture. Recent efforts have demonstrated that nanoscale strategies increase tolerance to both abiotic and biotic stressors, offering realistic potential to generate climate resilient crops. Considering the efficiency of nanoscale materials, there is a need to make their production more economical, alongside efficient use of incumbent resources such as water and energy. The hallmark of many of these approaches involves much greater impact with far less input of material. However, demonstrations of efficacy at field scale are still insufficient in the literature, and a thorough understanding of mechanisms of action is both necessary and often not evident. Although nanotechnology holds great promise for combating global food insecurity, there are far more ways to do this poorly than safely and effectively. This review summarizes recent work in this space, calling out existing knowledge gaps and suggesting strategies to alleviate those concerns to advance the field of sustainable nano-enabled agriculture.

Characterization of Type1 Lipid Transfer Protein from Citrus sinensis: Unraveling its potential as an antimicrobial and insecticidal agent

Lipid Transfer Protein1 (LTP1) is a cationic, multifaceted protein belonging to the pathogenesis-related protein (PR14) family. Despite being involved in diverse physiological processes and defense mechanisms, the precise in-vivo role of LTP1 remains undiscovered. This work presents the characterization of recombinant Citrus sinensis LTP1 (CsLTP1) along with lipid binding studies through in-silico and in-vitro approaches. CsLTP1 demonstrated great thermal and pH stability with a huge biotechnological potential. It showed in-vitro binding capacity with jasmonic acid and lipids involved in regulating plant immune responses. Gene expression profiling indicated a significant upregulation of CsLTP1 in Candidatus-infected Citrus plants. CsLTP1 disrupted the cell membrane integrity of various pathogens, making it a potent antimicrobial agent. Further, in-vivo antimicrobial and insecticidal properties of CsLTP1 have been explored. The impact of exogenous CsLTP1 treatment on rice crop metabolism for managing blight disease has been studied using GC-MS. CsLTP1 triggered crucial metabolic pathways in rice plants while controlling the blight disease. CsLTP1 effectively inhibited Helicoverpa armigera larvae by impeding mid-gut α-amylase activity and obstructing its developmental stages. This study highlights the pivotal role of CsLTP1 in plant defense by offering insights for developing multi-target therapeutic agent or disease-resistant varieties to comprehensively tackle the challenges towards crop protection.

Exploring the potential of endophyte-plant interactions for improving crop sustainable yields in a changing climate

Climate change poses a major threat to global food security, significantly reducing crop yields as cause of abiotic stresses, and for boosting the spread of new and old pathogens and pests. Sustainable crop management as a route to mitigation poses the challenge of recruiting an array of solutions and tools for the new aims. Among these, the deployment of positive interactions between the micro-biotic components of agroecosystems and plants can play a highly significant role, as part of the agro-ecological revolution. Endophytic microorganisms have emerged as a promising solution to tackle this challenge. Among these, Arbuscular Mycorrhizal Fungi (AMF) and endophytic bacteria and fungi have demonstrated their potential to alleviate abiotic stresses such as drought and heat stress, as well as the impacts of biotic stresses. They can enhance crop yields in a sustainable way also by other mechanisms, such as improving the nutrient uptake, or by direct effects on plant physiology. In this review we summarize and update on the main types of endophytes, we highlight several studies that demonstrate their efficacy in improving sustainable yields and explore possible avenues for implementing crop-microbiota interactions. The mechanisms underlying these interactions are highly complex and require a comprehensive understanding. For this reason, omic technologies such as genomics, transcriptomics, proteomics, and metabolomics have been employed to unravel, by a higher level of information, the complex network of interactions between plants and microorganisms. Therefore, we also discuss the various omic approaches and techniques that have been used so far to study plant-endophyte interactions.

Antimicrobial Action Mechanisms of Natural Compounds Isolated from Endophytic Microorganisms

Infectious diseases are a significant challenge to global healthcare, especially in the face of increasing antibiotic resistance. This urgent issue requires the continuous exploration and development of new antimicrobial drugs. In this regard, the secondary metabolites derived from endophytic microorganisms stand out as promising sources for finding antimicrobials. Endophytic microorganisms, residing within the internal tissues of plants, have demonstrated the capacity to produce diverse bioactive compounds with substantial pharmacological potential. Therefore, numerous new antimicrobial compounds have been isolated from endophytes, particularly from endophytic fungi and actinomycetes. However, only a limited number of these compounds have been subjected to comprehensive studies regarding their mechanisms of action against bacterial cells. Furthermore, the investigation of their effects on antibiotic-resistant bacteria and the identification of biosynthetic gene clusters responsible for synthesizing these secondary metabolites have been conducted for only a subset of these promising compounds. Through a comprehensive analysis of current research findings, this review describes the mechanisms of action of antimicrobial drugs and secondary metabolites isolated from endophytes, antibacterial activities of the natural compounds derived from endophytes against antibiotic-resistant bacteria, and biosynthetic gene clusters of endophytic fungi responsible for the synthesis of bioactive secondary metabolites.

Potential of the quorum-quenching and plant-growth promoting halotolerant Bacillus toyonensis AA1EC1 as biocontrol agent

The use of fertilizers and pesticides to control plant diseases is widespread in intensive farming causing adverse effects together with the development of antimicrobial resistance pathogens. As the virulence of many Gram-negative phytopathogens is controlled by N-acyl-homoserine lactones (AHLs), the enzymatic disruption of this type of quorum-sensing (QS) signal molecules, mechanism known as quorum quenching (QQ), has been proposed as a promising alternative antivirulence therapy. In this study, a novel strain of Bacillus toyonensis isolated from the halophyte plant Arthrocaulon sp. exhibited numerous traits associated with plant growth promotion (PGP) and degraded a broad range of AHLs. Three lactonases and an acylase enzymes were identified in the bacterial genome and verified in vitro. The AHL-degrading activity of strain AA1EC1 significantly attenuated the virulence of relevant phytopathogens causing reduction of soft rot symptoms on potato and carrots. In vivo assays showed that strain AA1EC1 significantly increased plant length, stem width, root and aerial dry weights and total weight of tomato and protected plants against Pseudomonas syringae pv. tomato. To our knowledge, this is the first report to demonstrate PGP and QQ activities in the species B. toyonensis that make this strain as a promising phytostimulant and biocontrol agent.

Bioinspired total synthesis and biological activity of Pegaharine A

BACKGROUND

Phytopathogens cause various diseases by parasitizing crops, reducing crop yield and resulting in substantial economic losses in agricultural production. A novel type isolated from the perennial herbaceous Peganum harmala L. seeds, β-carboline alkaloids pegaharine A (PA), has become a hot topic in developing plant-originated green pesticides owing to their significant physiological activities.

RESULTS

A scalable bioinspired total synthesis of PA is accomplished in the present work. The systematical biological assay study showed that PA exhibited moderate inhibitory activity against nine tested plant pathogenic fungi and showed significant inhibitory activity in vitro against the three tested plant pathogenic bacteria. Most noteworthy is the inhibitory rates of PA on Xanthomonas oryzae pv. oryzae (Xoo), X. oryzae pv. oryzicola (Xoc) and X. axonopodis pv. citri (Xac) of 93.6%, 92.1% and 86.1%, respectively, which are better than the control drug, bismerthiazol (63.4%, 61.2% and 53.7% at 100 μg mL-1 concentration). Furthermore, the EC50 value of PA against Xoo, Xoc and Xac was 52.2, 60.0 and 65.1 μg mL-1 , respectively, superior to 72.9, 64.2 and 70.1 μg mL-1 of the control drug. Moreover, the anti-Xoo mechanistic studies revealed that PA exerted its antibacterial effects by increasing the permeability of the bacterial membrane, reducing the extracellular polysaccharide content and inducing morphological changes in bacterial cells.

CONCLUSION

A novel β-carboline alkaloid, PA, was prepared by biomimetic total synthesis. Its significant antibacterial activity was closely related to the permeation of bacterial cell membranes, which was confirmed by anti-Xoo mechanistic studies. More importantly, the structure could be regarded as a model for developing novel bactericides. © 2023 Society of Chemical Industry.

Recent advances in immuno-based methods for the detection of Ralstonia solanacearum

Ralstonia solanacearum (RS) is a widely recognized phytopathogenic bacterium which is responsible for causing devastating losses in a wide range of economically significant crops. Timely and accurate detection of this pathogen is pivotal to implementing effective disease management strategies and preventing crop losses. This review provides a comprehensive overview of recent advances in immuno-based detection methods for RS. The review begins by introducing RS, highlighting its destructive potential and the need for point-of-care detection techniques. Subsequently, it explores traditional detection methods and their limitations, emphasizing the need for innovative approaches. The main focus of this review is on immuno-based detection methods and it discusses recent advancements in serological detection techniques. Furthermore, the review sheds light on the challenges and prospects of immuno-based detection of RS. It emphasizes the importance of developing rapid, field-deployable assays that can be used by farmers and researchers alike. In conclusion, this review provides valuable insights into the recent advances in immuno-based detection methods for RS.

Development and evaluation of eco-friendly carvacrol nanoemulsion as a sustainable biopesticide against bacterial leaf blight of cluster bean

BACKGROUND

The study of carvacrol plant antibacterial components has recently become a hot topic in modern farming. Carvacrol industrial applications are restricted by their physicochemical instability and partial solubility in water. In the present study, an ultrasonic emulsification method was used to prepare a carvacrol nanoemulsion (CAR-NE) employing nonionic surfactants. The CAR-NE was characterized using a dynamic light scattering (DLS) instrument and transmission electron microscopy (TEM). The goal of this work was nanoencapsulation of carvacrol to improve its aqueous solubility and preservation of the encapsulated compound against climatic conditions. Another aim of the present study was the evaluation of the growth-promoting effects and antibacterial potential of CAR-NE against bacterial leaf blight of cluster bean.

RESULTS

CAR-NE showed a hydrodynamic diameter, ZP and PDI index of 43.88 ± 4.30 nm, -47.8 ± 0.23 mV and 0.246 ± 0.04, respectively. The spherical shape morphology of CAR-NE was confirmed by TEM imaging. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the CAR-NE were 20 and 160 μL mL-1 (respectively) against Xanthomonas axonopodis pv. cyamopsidis. Additionally, the antibacterial potential of CAR-NE was evaluated for controlling bacterial blight of cluster bean in fields. The disease severity in the negative control plants (water) was 84%, but that in the CAR-NE 160 (μL mL-1 ) was remarkably low at 14%, nearly the same as the positive control (streptomycin sulfate).

CONCLUSION

The shelf-life of CAR-NE was 2 months at room temperature without any appreciable changes in hydrodynamic diameter and zeta potential. Consequently, plants treated with CAR-NE 160 showed substantial improvement in plant growth. © 2023 Society of Chemical Industry.

Label-Free Surface-Enhanced Raman Scattering Detection of Fire Blight Pathogen Using a Pathogen-Specific Bacteriophage

Fire blight is one of the most devastating plant diseases, causing severe social and economic problems. Herein, we report a novel method based on label-free surface-enhanced Raman scattering (SERS) combined with an Erwinia amylovora-specific bacteriophage that allows detecting efficiently fire blight bacteria E. amylovora for the first time. To achieve the highest SERS signals for E. amylovora, we synthesized and compared plasmonic nanoparticles (PNPs) with different sizes, i.e., bimetallic gold core-silver shell nanoparticles (Au@AgNPs) and monometallic gold nanoparticles (AuNPs) and utilized the coffee-ring effect for the self-assembly of PNPs and enrichment of fire blight bacteria. Furthermore, we investigated the changes in the SERS spectra of E. amylovora after incubation with an E. amylovora-specific bacteriophage, and we found considerable differences in the SERS signals as a function of the bacteriophage incubation time. The results indicate that our bacteriophage-based label-free SERS analysis can specifically detect E. amylovora without the need for peak assignment on the SERS spectra but simply by monitoring the changes in the SERS signals over time. Therefore, our facile method holds great potential for the label-free detection of pathogenic bacteria and the investigation of viral-bacterial interactions.

Silver nanoparticles improve the fungicidal properties of Rhazya stricta decne aqueous extract against plant pathogens

One of the most promising, non-toxic, and biocompatible developments for many biological activities is the green synthesis of nanoparticles from plants. In this work, we investigated the antifungal activity of silver nanoparticles (AgNPs) biosynthesized from Rhazya stricta aqueous extract against several plant pathogenic fungi. UV-visible spectroscopy, Zeta potential analysis, Fourier-transform infrared spectroscopy (FTIR), and transmitted electron microscopy (TEM) were used to analyze the biosynthesized AgNPs. Drechslera halodes, Drechslera tetramera, Macrophomina phaseolina, Alternaria alternata, and Curvularia australiensis were tested for their potential antifungal activity. Surface Plasmon Resonance (SPR) of Aq. AgNPs and Alkaline Aq. AgNPs was observed at 405 nm and 415 nm, respectively. FTIR analysis indicated hydroxyl, nitrile, amine, and ketone functional groups. Aq. AgNPs and Alka-line Aq. AgNPs had velocities of - 27.7 mV and - 37.9 mV and sizes of 21-90 nm and 7.2-25.3 nm, respectively, according to zeta potential studies and TEM. The antifungal examination revealed that all species' mycelial development was significantly inhibited, accompanied by severe ultra-structural alterations. Among all treatments, Aq. AgNPs were the most effective fungicide. M. phaseolina was statistically the most resistant, whereas A. alternata was the most vulnerable. To the best of our knowledge, this is the first report on R. stricta's antifungal activity against these species.

Effect of multiple nonthermal plasma treatments of filamentous fungi on cellular phenotypic changes and phytopathogenicity

The effect of multiple sublethal doses of non-thermal plasma treatments on fungal cells phenotypical changes and the reduction in phytopathogenicity of Fusarium oxysporum, Botrytis cinerea, and Alternaria alternata was examined. The intensity of these changes depended on the species of fungus and the number of exposures of the mycelia to the DBD plasma. Microscopic observations showed that the plasma damaged the surface of the hyphae, increased their thickness and decreased overall dry biomass of the organisms. A decrease in pectinolytic activity was found in F. oxysporum and A. alternata, in contrast to B. cinerea, where an increase in pectinolytic activity was observed after the fifth plasma treatment. Changes in specific xylanase activity varied and were dependent on the species of fungus. The percentage of cucumber seeds germinated artificially infected with mycelium after multiple plasma treatments increased compared to those that were mycelium infected prior to plasma exposure. Plants that developed from seeds after plasma exposure were characterized by a higher biomass and longer roots and stems. Multiple treatments of the studied fungi with plasma, followed by seed infection, increased the SWVI and SWVI indexes of cucumber seedlings, but they did not reach the characteristic value of the control seeds (not infected with fungi). The reduced phytopathogenicity of the tested fungi was confirmed by artificial infestation of tomato fruits.

A mathematical model for frogeye leaf spot epidemics in soybean

We propose a new mathematical model based on differential equations to investigate the transmission and spread of frogeye leaf spot, a major soybean disease caused by the fungus Cercospora sojina. The model incorporates the primary and secondary transmission routes of the disease as well as the intrinsic dynamics of the pathogen in the contaminated soil. We conduct detailed equilibrium and stability analyses for this model using theories of dynamical systems. We additionally conduct numerical simulations to verify the analytical predictions and to implement the model for a practical application.

Determining Macromolecular Structures Using Cryo-Electron Microscopy

Structural insights into macromolecular and protein complexes provide key clues about the molecular basis of the function. Cryogenic electron microscopy (cryo-EM) has emerged as a powerful structural biology method for studying protein and macromolecular structures at high resolution in both native and near-native states. Despite the ability to get detailed structural insights into the processes underlying protein function using cryo-EM, there has been hesitancy amongst plant biologists to apply the method for biomolecular interaction studies. This is largely evident from the relatively fewer structural depositions of proteins and protein complexes from plant origin in electron microscopy databank. Even though the progress has been slow, cryo-EM has significantly contributed to our understanding of the molecular biology processes underlying photosynthesis, energy transfer in plants, besides viruses infecting plants. This chapter introduces sample preparation for both negative-staining electron microscopy (NSEM) and cryo-EM for plant proteins and macromolecular complexes and data analysis using single particle analysis for beginners.

Virulence factors of the genus Fusarium with targets in plants

Fusarium spp. comprise various species of filamentous fungi that cause severe diseases in plant crops of both agricultural and forestry interest. These plant pathogens produce a wide range of molecules with diverse chemical structures and biological activities. Genetic functional analyses of some of these compounds have shown their role as virulence factors (VF). However, their mode of action and contributions to the infection process for many of these molecules are still unknown. This review aims to analyze the state of the art in Fusarium VF, emphasizing their biological targets on the plant hosts. It also addresses the current experimental approaches to improve our understanding of their role in virulence and suggests relevant research questions that remain to be answered with a greater focus on species of agroeconomic importance. In this review, a total of 37 confirmed VF are described, including 22 proteinaceous and 15 non-proteinaceous molecules, mainly from Fusarium oxysporum and Fusarium graminearum and, to a lesser extent, in Fusarium verticillioides and Fusarium solani.

Biocontrol rhizobacteria enhances growth and yield of wheat (Triticum aestivum) under field conditions against Fusarium oxysporum

The current study aimed to identify the survival of bio-control bacteria with antifungal activity against Fusarium oxysporum and assess their growth promoting activity in wheat crop field conditions. To evaluate the fungicidal activities of isolated bacteria using the dual culture method, both qualitative and quantitative bioassays were performed. Plant Growth Promoting activities such as Indole 3-Acetic Acid (IAA), phosphate solubilization, Hydrogen cyanide (HCN), and Siderophore production were assessed for three biocontrol bacterial isolates (BCB 07, BCB16, and BCB 83) out of 180 with 70% antagonistic activity against Fusarium oxysporum. Chitinase, protease, and cellulase interaction in isolates was also tested. BCB16 was selected as it had 70% antagonist activity against F. oxysporum but also had the highest PGPR (Plant Growth Promoting Rhizobacteria) traits when compared to the other two isolates. BCB16 was also tested for survival in talc powder and in wheat crop field conditions. Even after 4 months in talc powder, the survival rate remained stable. In a wheat crop field, BCB16 reduced the disease incidence of Fusarium oxysporum by 54.38%. When compared to fungus alone treatment, BCB16 increased average yield by 57% alone and 32% in challenged conditions. BCB16 was identified molecularly using the 16s rRNA gene. Bacillus amyloliquefaciens shared 97% of the deduced sequence. The sequence was submitted to genbank and assigned the accession number OM333889. Bacillus amyloliquefaciens has the potential to be used in the field as an alternative to synthetic fungicides against Fusarium oxysporum.

Streptomyces as a promising biological control agents for plant pathogens

Plant diseases caused by pathogenic microorganisms in agriculture present a considerable obstacle, resulting in approximately 30-40% crop damage. The use of conventional techniques to manage these microorganisms, i.e., applying chemical pesticides and antimicrobials, has been discovered to have adverse effects on human health and the environment. Furthermore, these methods have contributed to the emergence of resistance among phytopathogens. Consequently, it has become imperative to investigate natural alternatives to address this issue. The Streptomyces genus of gram-positive bacteria is a potentially viable natural alternative that has been extensively researched due to its capacity to generate diverse antimicrobial compounds, such as metabolites and organic compounds. Scientists globally use diverse approaches and methodologies to extract new bioactive compounds from these bacteria. The efficacy of bioactive compounds in mitigating various phytopathogens that pose a significant threat to crops and plants has been demonstrated. Hence, the Streptomyces genus exhibits potential as a biological control agent for combating plant pathogens. This review article aims to provide further insight into the Streptomyces genus as a source of antimicrobial compounds that can potentially be a biological control against plant pathogens. The investigation of various bioactive compounds synthesized by this genus can enhance our comprehension of their prospective utilization in agriculture.

Comparison of the Efficiency of Hyperspectral and Pulse Amplitude Modulation Imaging Methods in Pre-Symptomatic Virus Detection in Tobacco Plants

Early detection of pathogens can significantly reduce yield losses and improve the quality of agricultural products. This study compares the efficiency of hyperspectral (HS) imaging and pulse amplitude modulation (PAM) fluorometry to detect pathogens in plants. Reflectance spectra, normalized indices, and fluorescence parameters were studied in healthy and infected areas of leaves. Potato virus X with GFP fluorescent protein was used to assess the spread of infection throughout the plant. The study found that infection increased the reflectance of leaves in certain wavelength ranges. Analysis of the normalized reflectance indices (NRIs) revealed indices that were sensitive and insensitive to infection. NRI700/850 was optimal for virus detection; significant differences were detected on the 4th day after the virus arrived in the leaf. Maximum (Fv/Fm) and effective quantum yields of photosystem II (ΦPSII) and non-photochemical fluorescence quenching (NPQ) were almost unchanged at the early stage of infection. ΦPSII and NPQ in the transition state (a short time after actinic light was switched on) showed high sensitivity to infection. The higher sensitivity of PAM compared to HS imaging may be due to the possibility of assessing the physiological changes earlier than changes in leaf structure.

In Vitro Assessment of Eight Selected Indigenous Fungal Isolates Tolerance to Various Abiotic Stresses and their Effects on Seed Germination

Fungal bio-control agents (BCA) can minimize use of agro-chemicals while increasing plant productivity and tolerance to biotic-abiotic stressors. Ideally, BCA should tolerate varying environmental conditions they are introduced into, to successfully dominate and protect plants from stressors. However, BCA are living micro-organisms, their survival and efficacy can be impeded by extreme conditions. The current study aimed at evaluating whether indigenous fungal isolates, viz, Aspergillus flavus, A. terreus, Penicillium sp. AL-38 IRH-2012b, Talaromyces minioluteus, T. purpureogenus, T. sayulitensis, Trichoderma ghanense and T. viride can tolerate different levels of salinity, pH, nutrient and temperature. Certain fungal species are pests with potential of destroying many crops; the pathogenic effects of the aforementioned fungal isolates were further assessed on different crops' seeds. The results showed that, although being indigenous, Aspergillus, T. sayulitensis and T. ghanense failed to thrive in high salinity and pH. While Penicillium sp. AL-38 IRH-2012b failed to thrive under reduced nutrient level and all fungal isolates failed to grow at 10-20 °C. Furthermore, it was noted species within the same genus could affect crops in both favorable and unfavorable ways. The study demonstrated that the selected indigenous fungal isolates can tolerate different abiotic conditions and have potential to improve seed germination and seedling growth.

Current Scenario and Future Prospects of Endophytic Microbes: Promising Candidates for Abiotic and Biotic Stress Management for Agricultural and Environmental Sustainability

Globally, substantial research into endophytic microbes is being conducted to increase agricultural and environmental sustainability. Endophytic microbes such as bacteria, actinomycetes, and fungi inhabit ubiquitously within the tissues of all plant species without causing any harm or disease. Endophytes form symbiotic relationships with diverse plant species and can regulate numerous host functions, including resistance to abiotic and biotic stresses, growth and development, and stimulating immune systems. Moreover, plant endophytes play a dominant role in nutrient cycling, biodegradation, and bioremediation, and are widely used in many industries. Endophytes have a stronger predisposition for enhancing mineral and metal solubility by cells through the secretion of organic acids with low molecular weight and metal-specific ligands (such as siderophores) that alter soil pH and boost binding activity. Finally, endophytes synthesize various bioactive compounds with high competence that are promising candidates for new drugs, antibiotics, and medicines. Bioprospecting of endophytic novel secondary metabolites has given momentum to sustainable agriculture for combating environmental stresses. Biotechnological interventions with the aid of endophytes played a pivotal role in crop improvement to mitigate biotic and abiotic stress conditions like drought, salinity, xenobiotic compounds, and heavy metals. Identification of putative genes from endophytes conferring resistance and tolerance to crop diseases, apart from those involved in the accumulation and degradation of contaminants, could open new avenues in agricultural research and development. Furthermore, a detailed molecular and biochemical understanding of endophyte entry and colonization strategy in the host would better help in manipulating crop productivity under changing climatic conditions. Therefore, the present review highlights current research trends based on the SCOPUS database, potential biotechnological interventions of endophytic microorganisms in combating environmental stresses influencing crop productivity, future opportunities of endophytes in improving plant stress tolerance, and their contribution to sustainable remediation of hazardous environmental contaminants.

Bi-directional Dual-flow-RootChip for Physiological Analysis of Plant Primary Roots Under Asymmetric Perfusion of Stress Treatments

Due to technical limitations, research to date has mainly focused on the role of abiotic and biotic stress-signalling molecules in the aerial organs of plants, including the whole shoot, stem, and leaves. Novel experimental platforms including the dual-flow-RootChip (dfRC), PlantChip, and RootArray have since expanded this to plant-root cell analysis. Based on microfluidic platforms for flow stream shaping and force sensing on tip-growing organisms, the dfRC has further been expanded into a bi-directional dual-flow-RootChip (bi-dfRC), incorporating a second adjacent pair of inlets/outlet, enabling bi-directional asymmetric perfusion of treatments towards plant roots (shoot-to-root or root-to-shoot). This protocol outlines, in detail, the design and use of the bi-dfRC platform. Plant culture on chip is combined with guided root growth and controlled exposure of the primary root to solute changes. The impact of surface treatment on root growth and defence signals can be tracked in response to abiotic and biotic stress or the combinatory effect of both. In particular, this protocol highlights the ability of the platform to culture a variety of plants, such as Arabidopsis thaliana, Nicotiana benthamiana, and Solanum lycopersicum, on chip. It demonstrates that by simply altering the dimensions of the bi-dfRC, a broad application basis to study desired plant species with varying primary root sizes under microfluidics is achieved. Key features Expansion of the method developed by Stanley et al. (2018a) to study the directionality of defence signals responding to localised treatments. Description of a microfluidic platform allowing culture of plants with primary roots up to 40 mm length, 550 μm width, and 500 μm height. Treatment with polyvinylpyrrolidone (PVP) to permanently retain the hydrophilicity of partially hydrophobic bi-dfRC microchannels, enabling use with surface-sensitive plant lines. Description of novel tubing array setup equipped with rotatable valves for switching treatment reagent and orientation, while live-imaging on the bi-dfRC. Graphical overview Graphical overview of bi-dfRC fabrication, plantlet culture, and setup for root physiological analysis.(a) Schematic diagram depicting photolithography and replica molding, to produce a PDMS device. (b) Schematic diagram depicting seed culture off chip, followed by sub-culture of 4-day-old plantlets on chip. (c) Schematic diagram depicting microscopy and imaging setup, equipped with a media delivery system for asymmetric treatment introduction into the bi-dfRC microchannel root physiological analysis under varying conditions.

Current Insights in Fungal Importance-A Comprehensive Review

Besides plants and animals, the Fungi kingdom describes several species characterized by various forms and applications. They can be found in all habitats and play an essential role in the excellent functioning of the ecosystem, for example, as decomposers of plant material for the cycling of carbon and nutrients or as symbionts of plants. Furthermore, fungi have been used in many sectors for centuries, from producing food, beverages, and medications. Recently, they have gained significant recognition for protecting the environment, agriculture, and several industrial applications. The current article intends to review the beneficial roles of fungi used for a vast range of applications, such as the production of several enzymes and pigments, applications regarding food and pharmaceutical industries, the environment, and research domains, as well as the negative impacts of fungi (secondary metabolites production, etiological agents of diseases in plants, animals, and humans, as well as deteriogenic agents).

A Novel Feature Selection Strategy Based on Salp Swarm Algorithm for Plant Disease Detection

Deep learning has been widely used for plant disease recognition in smart agriculture and has proven to be a powerful tool for image classification and pattern recognition. However, it has limited interpretability for deep features. With the transfer of expert knowledge, handcrafted features provide a new way for personalized diagnosis of plant diseases. However, irrelevant and redundant features lead to high dimensionality. In this study, we proposed a swarm intelligence algorithm for feature selection [salp swarm algorithm for feature selection (SSAFS)] in image-based plant disease detection. SSAFS is employed to determine the ideal combination of handcrafted features to maximize classification success while minimizing the number of features. To verify the effectiveness of the developed SSAFS algorithm, we conducted experimental studies using SSAFS and 5 metaheuristic algorithms. Several evaluation metrics were used to evaluate and analyze the performance of these methods on 4 datasets from the UCI machine learning repository and 6 plant phenomics datasets from PlantVillage. Experimental results and statistical analyses validated the outstanding performance of SSAFS compared to existing state-of-the-art algorithms, confirming the superiority of SSAFS in exploring the feature space and identifying the most valuable features for diseased plant image classification. This computational tool will allow us to explore an optimal combination of handcrafted features to improve plant disease recognition accuracy and processing time.

Penetration of Triphenylphosphonium Derivatives through the Cell Envelope of Bacteria of Mycobacteriales Order

The penetration of substances through the bacterial cell envelope is a complex and underinvestigated process. Mitochondria-targeted antioxidant and antibiotic SkQ1 (10-(plastoquinonyl)decyltriphenylphosphonium) is an excellent model for studying the penetration of substances through the bacterial cell envelope. SkQ1 resistance in Gram-negative bacteria has been found to be dependent on the presence of the AcrAB-TolC pump, while Gram-positive bacteria do not have this pump but, instead, have a mycolic acid-containing cell wall that is a tough barrier against many antibiotics. Here, we report the bactericidal action of SkQ1 and dodecyl triphenylphospho-nium (C₁₂TPP) against Rhodococcus fascians and Mycobacterium tuberculosis, pathogens of plants and humans. The mechanism of the bactericidal action is based on the penetration of SkQ1 and C₁₂TPP through the cell envelope and the disruption of the bioenergetics of bacteria. One, but probably not the only such mechanism is a decrease in membrane potential, which is important for the implementation of many cellular processes. Thus, neither the presence of MDR pumps, nor the presence of porins, prevents the penetration of SkQ1 and C₁₂TPP through the complex cell envelope of R. fascians and M. tuberculosis.

Design, synthesis, crystal structure, and antimicrobial activities of new quinazoline derivatives containing both the sulfonate ester and piperidinylamide moieties

BACKGROUND

To discover more efficient antimicrobial agents in agriculture, a series of new quinazoline derivatives bearing both sulfonate ester and piperidine-4-carboxamide moieties were synthesized and assessed for their antimicrobial effects.

RESULTS

All of the target compounds were fully characterized by proton (¹ H) nuclear magnetic resonance (NMR), carbon-13 (¹³ C) NMR, and high-resolution mass spectroscopy (HRMS), and compound III-6 containing a 3-bromophenyl substituent was clearly confirmed via single-crystal X-ray diffraction analysis. The bioassay results indicated that some compounds displayed noticeable inhibitory effects in vitro against Xanthomonas oryzae pv. oryzicola (Xoc). Further measurements of median effective concentration (EC₅₀ ) values showed that compound III-17 bearing a 4-methoxyphenyl group had the best anti-Xoc efficacy (EC₅₀  = 12.4 μg mL^-1 ), far better than the commercialized bismerthiazol (77.5 μg mL^-1 ). Moreover, this compound also demonstrated good protection and curative activities in vivo against rice bacterial leaf streak caused by Xoc.

CONCLUSION

Compound III-17 had a good potential for further development as a new bactericide for controlling Xoc. © 2023 Society of Chemical Industry.