Plant Disease Management Research Articles

Bacterial agents for controlling anthracnose and soft rot in strawberries: present status and perspectives

ABSTRACT Anthracnose and soft rot, caused by the fungal pathogens Colletotrichum spp. and Rhizopus spp., respectively, stand as prominent diseases impacting strawberries during the postharvest phase, resulting in significant economic losses. The use of conventional treatments involving chemical fungicides has been discouraged since they negatively impact the environment and human health. In this context, alternative strategies, such as biological control, have been required for organic and sustainable agriculture. While bacterial agents, such as Bacillus spp., are successfully used in commercial formulations to control postharvest diseases, there are other bacteria exhibiting antagonistic activities that hold potential in plant disease management. Hence, the current review aims to investigate studies developed over the past decade describing the primary bacterial genera with the potential to inhibit the causal agents of soft rot and anthracnose. Additionally, it aims to provide an overview of biocontrol mechanisms for suppressing these pathogens, detailing methods of application in both pre and postharvest phases, along with strategies for enhancing the efficacy of biocontrol agents. The findings of this review demonstrate that numerous bacterial species possess the ability to effectively control anthracnose and soft rot, both in growing plants and harvested strawberries. This expands the available forms of control and minimises the occurrence of resistant pathogens. Furthermore, the application of postharvest techniques such as edible coatings and bacterial encapsulation proves advantageous, extending fruit shelf life and reducing strawberry decay.

Molybdenum inhibited the growth of Phytophthora nicotiana and improved the resistance of Nicotiana tabacum L. against tobacco black shank

Tobacco black shank (TBS) is a soil-borne fungal disease caused by Phytophthora nicotiana (P. nicotianae), significantly impeding the production of high-quality tobacco. Molybdenum (Mo), a crucial trace element for both plants and animals, plays a vital role in promoting plant growth, enhancing photosynthesis, bolstering antioxidant capacity, and maintaining ultrastructural integrity. However, the positive effect of Mo on plant biotic stress is little understood. This study delves into the inhibitory effects of Mo on P. nicotianae and seeks to unravel the underlying mechanisms. The results showed that 16.32 mg/L of Mo significantly inhibited mycelial growth, altered mycelial morphological structure, damaged mycelial cell membrane, and ultimately led to the leakage of cell inclusions. In addition, 0.6 mg/kg Mo applied in soil significantly reduced the severity of TBS. Mo increased photosynthetic parameters and photosynthetic pigment contents of tobacco leaves, upregulated expression of NtPAL and NtPPO resistance genes, as well as improved activities of SOD, POD, CAT, PPO, and PAL in tobacco plants. Furthermore, Mo could regulate nitrogen metabolism and amino acids metabolism to protect tobacco plants against P. nicotianae infection. These findings not only present an ecologically sound approach to control TBS but also contribute valuable insights to the broader exploration of the role of microelements in plant disease management.

Multidrug resistance of Botrytis cinerea associated with its adaptation to plant secondary metabolites.

Fungicides are an effective way to control gray mold of grapes, but the pathogen Botrytis cinerea can develop resistance, overcoming the effectiveness of a fungicide that is repeatedly applied. More importantly, the emergence of multidrug resistance (MDR) in the field, where multiple fungicides with different modes of action simultaneously lose their efficacies, is a significant concern. MDR is associated with ATP-binding cassette (ABC) transporters of the pathogen, and certain plant secondary metabolites (PSMs) stimulate the upregulation of ABC transporters, we hypothesized that the pathogen's preadaptation to PSMs might contribute to MDR development. To test this in B. cinerea, ten PSMs, namely, resveratrol, reserpine, chalcone, flavanone, eugenol, farnesol, anethene, camptothecin, salicylic acid, and psoralen, were selected based on their association with ABC transporters involved in fungicide resistance. B. cinerea strain B05.10 was continuously transferred for 15 generations on potato dextrose agar amended with a PSM (PDAP), and sensitivities to PSMs and fungicides were examined on the 5th, 10th, and 15th generations. RNA was extracted from B. cinerea from the selected generations. After 15 generations of culture transfers, an up-regulation was observed in the expression of ABC transporter-encoding genes BcatrB, BcatrD, and BcatrK using quantitative polymerase chain reaction (qPCR). This upregulation was found to contribute to MDR of B. cinerea against two or more fungicides, among azoxystrobin, boscalid, fludioxonil, difenoconazole, prochloraz, and pyrimethanil. This finding was confirmed through genetic transformation. The decreased sensitivity of B. cinerea to fungicides was confirmed as a subsequent MDR phenotype after exposure to camptothecin, flavanone, and resveratrol. Besides, transcriptome analysis also revealed the upregulation of transcription factors related to ABC expression following resveratrol exposure. This suggests that PSMs contributed to inducing preadaptation of B. cinerea, leading to subsequent MDR.IMPORTANCEThe emergence of MDR in plant pathogens is a threat to plant disease management and leads to the use of excessive fungicides. Botrytis cinerea is of particular concern because its MDR has widely emerged in the field. Understanding its genesis is the first step for controlling MDR. In this study, the contribution of PSMs to MDR has been examined. Effective management of this pathogen in agroecosystems relies on a better understanding of how it copes with phytochemicals or fungicides.

Fabrication of Hollow Mesoporous Copper Sulfide Nanocapsules Loaded with Natural Photoactivated Pesticides for Sustainable Plant Disease Management

Fabrication of Hollow Mesoporous Copper Sulfide Nanocapsules Loaded with Natural Photoactivated Pesticides for Sustainable Plant Disease Management

The molecular structure, biological roles, and inhibition of plant pathogenic fungal chitin deacetylases.

Chitin/polysaccharide deacetylases belong to the carbohydrate esterases family 4 (CE4 enzymes). They play a crucial role in modifying the physiochemical characteristics of structural polysaccharides and are also involved in a wide range of biological processes such as fungal autolysis, spore formation, cell wall formation and integrity, and germling adhesion. These enzymes are mostly common in fungi, marine bacteria, and a limited number of insects. They facilitate the deacetylation of chitin which is a structural biopolymer that is abundantly found in fungal cell walls and spores and also in the cuticle and peritrophic matrices of insects. The deacetylases exhibit specificity towards a substrate containing a sequence of four GlcNAc units, with one of these units being subjected to deacetylation. Chitin deacetylation results in the formation of chitosan, which is a poor substrate for host plant chitinases, therefore it can suppress the host immune response triggered by fungal pathogens and enhance pathogen virulence and colonization. This review discusses plant pathogenic fungal chitin/polysaccharide deacetylases including their structure, substrate specificity, biological roles and some recently discovered chitin deacetylase inhibitors that can help to mitigate plant fungal diseases. This review provides fundamental knowledge that will undoubtedly lead to the rational design of novel inhibitors that target pathogenic fungal chitin deacetylases, which will also aid in the management of plant diseases, thereby safeguarding global food security.

Phytopathological management through bacteriophages: enhancing food security amidst climate change.

The burden of plant diseases and phage-based phytopathological treatment.

Physiological and Biochemical Mechanisms of Wood Vinegar-Induced Stress Response against Tomato Fusarium Wilt Disease.

Wood vinegar, a by-product of charcoal biomass pyrolysis, has been used as a biofungicide in plant disease management because of its antimicrobial properties. However, the physiological and biochemical mechanisms through which wood vinegar alleviates biotic stress are poorly understood. In this study, pot experiments were conducted to investigate the resistance and regulation mechanism of wood vinegar prepared from different raw materials (ZM) and from a single raw material (SM) in controlling tomato (Solanum lycopersicum "Bonny Best") Fusarium wilt at different concentrations (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The results showed that ZM and SM had significant control effects on tomato fusarium wilt under different concentrations in the same growth cycle. Under biotic stress, the two kinds of wood vinegar significantly increased the plant height, stem diameter, leaf area and yield of tomato under the concentration of 0.3%, 0.6%, 0.9% and 1.2%, and significantly reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in tomato leaves. The effect of 0.9% treatment was the most significant, ZM and SM significantly increased tomato yield by 122% and 74%, respectively, compared with CK under 0.9% treatment. However, the plant height, stem diameter and leaf area of tomato were significantly reduced under 1.5% treatment, but the content of soluble sugar, soluble protein and vitamin C in tomato fruit was the best. Compared with CK, ZM significantly increased by 14%, 193% and 67%, respectively, and SM significantly increased by 28%, 300% and 159%, respectively. Except for 0.3% treatment, both significantly increased the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in tomato leaves. The response intensity of two kinds of wood vinegar-physiological and biochemical-to tomato disease resistance, growth and development, showed ZM > SM. The disease index of tomato showed highly significant negative correlation with plant height, stem thickness, leaf area and antioxidant physiology CAT, and highly significant positive correlation with MDA and H2O2 content. In conclusion, ZM was more effective than SM in enhancing tomato disease resistance by promoting tomato growth and development, decreasing leaf MDA and H2O2 content, and inducing antioxidant enzyme activity in leaves at moderate concentrations.

Exploration of a multifunctional biocontrol agent Streptomyces sp. JCK-8055 for the management of apple fire blight.

Apple fire blight, caused by the bacterium Erwinia amylovora, is a devastating disease of apple and pear trees. Biological control methods have attracted much attention from researchers to manage plant diseases as they are eco-friendly and viable alternatives to synthetic pesticides. Herein, we isolated Streptomyces sp. JCK-8055 from the root of pepper and investigated its mechanisms of action against E. amylovora. Streptomyces sp. JCK-8055 produced aureothricin and thiolutin, which antagonistically affect E. amylovora. JCK-8055 and its two active metabolites have a broad-spectrum in vitro activity against various phytopathogenic bacteria and fungi. They also effectively suppressed tomato bacterial wilt and apple fire blight in in vivo experiments. Interestingly, JCK-8055 colonizes roots as a tomato seed coating and induces apple leaf shedding at the abscission zone, ultimately halting the growth of pathogenic bacteria. Additionally, JCK-8055 can produce the plant growth regulation hormone indole-3-acetic acid (IAA) and hydrolytic enzymes, including protease, gelatinase, and cellulase. JCK-8055 treatment also triggered the expression of salicylate (SA) and jasmonate (JA) signaling pathway marker genes, such as PR1, PR2, and PR3. Overall, our findings demonstrate that Streptomyces sp. JCK-8055 can control a wide range of plant diseases, particularly apple fire blight, through a combination of mechanisms such as antibiosis and induced resistance, highlighting its excellent potential as a biocontrol agent. KEY POINTS: • JCK-8055 produces the systemic antimicrobial metabolites, aureothricin, and thiolutin. • JCK-8055 treatment upregulates PR gene expression in apple plants against E. amylovora. • JCK-8055 controls plant diseases with antibiotics and induced resistance.

Challenges and Opportunities in Plant Disease Management: A Brief Review

Plant diseases can reduce human food availability. Modern plant disease management faces problems due to climate change, fungicide resistance, pesticide residues and biodiversity loss. This review discusses problems and challenges in plant disease management and future research needs for effective management. Plant disease forecasting models can be used to predict plant diseases ahead of time. Protected cultivation combats climate change. It is necessary to find more evidence that plant pathogen diversity has a dilution effect on disease incidence. Deep learning-based disease diagnosis will help detect diseases faster. More hybrid fungicides should be developed to minimize fungicidal resistance problems. Among the molecular methods of plant disease management, RNA interference-mediated gene silencing and genome editing with CRISPR is more promising in plant disease management.

Overview of insights into the role of Bacillus species in drought stress alleviation and plant disease management

Drought and plant diseases are major constraints on crop production, causing significant losses. As the effects of climate change worsen, there is an urgent need to adopt sustainable agricultural strategies. Plant Growth-Promoting Bacteria (PGPB) are emerging as a promising approach, aimed at enhancing productivity and plant resilience to various stresses. Among them, Bacillus spp. are gaining research interest due to their unique ability to adapt to harsh environmental conditions and produce metabolites of interest in several sectors. Besides improving plant growth and yield, Bacillus plays a pivotal role in enhancing the ability of plants to withstand drought stress mainly by producing of water absorbing substances and enhancing water and nutrient uptake. Some Bacillus species are able to effectively resist plant pathogens through several mechanisms, including antibiosis, competition, induced systemic resistance (ISR), and enriching the microbiome of the soil, enabling them to become important biological agents in the management of plant diseases. This overview aims to highlight the potential of Bacillus species in sustainable agriculture, focusing on their role in mitigating drought stress and controlling plant diseases.

Assessing the In vitro Antagonistic Effects of Trichoderma and Pseudomonas Bioagents on Rice Sheath Blight Pathogen

Sheath blight, caused by the fungus Rhizoctonia solani, is a devastating disease that poses a significant threat to rice production worldwide. In recent years, biocontrol agents such as Trichoderma and Pseudomonas have gained attention for their potential to manage sheath blight while minimizing the environmental impact associated with chemical pesticides. The present investigation assessed the effect of Trichoderma harzianum and Pseudomonas fluorescens on Rhizoctonia solani in vitro after collection and mass multiplication from different locations. The dual culture assay revealed complex interactions between R. solani and biocontrol agents such as T. harzianum and Pseudomonas fluorescens. T. harzianum exhibited significant antagonistic activity, as evidenced by the inhibition of R. solani growth, hyphal coiling around R. solani mycelia, and direct mycoparasitic interactions. Pseudomonas fluorescens, on the other hand, demonstrated an indirect antagonistic effect by producing siderophores and antibiotics that hindered the growth of Rhizoctonia solani. Trichoderma harzianum isolate (IRRI-1) was found to be most inhibitory for Rhizoctonia solani in vitro followed by Trichoderma harzianum (SV-3) and Pseudomonas fluorescens (PF-2). These observations provide insights into the mechanisms underlying the biocontrol potential of T. harzianum and Pseudomonas fluorescens against R. solani. In conclusion, the dual culture assay proved to be an effective method for studying the interactions between R. solani and biocontrol agents. The findings contribute to our understanding of the underlying mechanisms of biocontrol agents and offer valuable information for the development of sustainable agricultural strategies aimed at managing plant diseases caused by R. solani.

Emerging trends in Maldi-Tof MS: transforming plant pathogen detection and disease management

Emerging trends in Maldi-Tof MS: transforming plant pathogen detection and disease management

Adoption of CRISPR-Cas for crop production: present status and future prospects.

Global food systems in recent years have been impacted by some harsh environmental challenges and excessive anthropogenic activities. The increasing levels of both biotic and abiotic stressors have led to a decline in food production, safety, and quality. This has also contributed to a low crop production rate and difficulty in meeting the requirements of the ever-growing population. Several biotic stresses have developed above natural resistance in crops coupled with alarming contamination rates. In particular, the multiple antibiotic resistance in bacteria and some other plant pathogens has been a hot topic over recent years since the food system is often exposed to contamination at each of the farm-to-fork stages. Therefore, a system that prioritizes the safety, quality, and availability of foods is needed to meet the health and dietary preferences of everyone at every time. This review collected scattered information on food systems and proposes methods for plant disease management. Multiple databases were searched for relevant specialized literature in the field. Particular attention was placed on the genetic methods with special interest in the potentials of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and Cas (CRISPR associated) proteins technology in food systems and security. The review reveals the approaches that have been developed to salvage the problem of food insecurity in an attempt to achieve sustainable agriculture. On crop plants, some systems tend towards either enhancing the systemic resistance or engineering resistant varieties against known pathogens. The CRISPR-Cas technology has become a popular tool for engineering desired genes in living organisms. This review discusses its impact and why it should be considered in the sustainable management, availability, and quality of food systems. Some important roles of CRISPR-Cas have been established concerning conventional and earlier genome editing methods for simultaneous modification of different agronomic traits in crops. Despite the controversies over the safety of the CRISPR-Cas system, its importance has been evident in the engineering of disease- and drought-resistant crop varieties, the improvement of crop yield, and enhancement of food quality.

Fungal-mediated synthesis of silver nanoparticles: a novel strategy for plant disease management.

Various traditional management techniques are employed to control plant diseases caused by bacteria and fungi. However, due to their drawbacks and adverse environmental effects, there is a shift toward employing more eco-friendly methods that are less harmful to the environment and human health. The main aim of the study was to biosynthesize silver Nanoparticles (AgNPs) from Rhizoctonia solani and Cladosporium cladosporioides using a green approach and to test the antimycotic activity of these biosynthesized AgNPs against a variety of pathogenic fungi. The characterization of samples was done by using UV-visible spectroscopy, SEM (scanning electron microscopy), FTIR (fourier transmission infrared spectroscopy), and XRD (X-ray diffractometry). During the study, the presence of strong plasmon absorbance bands at 420 and 450 nm confirmed the AgNPs biosynthesis by the fungi Rhizoctonia solani and Cladosporium cladosporioides. The biosynthesized AgNPs were 80-100 nm in size, asymmetrical in shape and became spherical to sub-spherical when aggregated. Assessment of the antifungal activity of the silver nanoparticles against various plant pathogenic fungi was carried out by agar well diffusion assay. Different concentration of AgNPs, 5 mg/mL 10 mg/mL and 15 mg/mL were tested to know the inhibitory effect of fungal plant pathogens viz. Aspergillus flavus, Penicillium citrinum, Fusarium oxysporum, Fusarium metavorans, and Aspergillus aflatoxiformans. However, 15 mg/mL concentration of the AgNPs showed excellent inhibitory activity against all tested fungal pathogens. Thus, the obtained results clearly suggest that silver nanoparticles may have important applications in controlling various plant diseases caused by fungi.

Application of dsRNA for Fungi Disease Management Sclerotinia sclerotiorum and Botrytis cinerea.

Sclerotinia sclerotiorum and Botrytis cinerea are two closely related necrotrophic plant pathogenic fungi that have garnered significant attention due to their broad host range and persistent environmental presence. The use of double-stranded RNA (dsRNA) to inhibit specific genes has demonstrated promising potential in disease management. Various RNA interference (RNAi) strategies have been developed and applied in disease management, including the use of dsRNA to silence specific genes, as well as other RNA-based approaches. These strategies show promise in controlling fungal diseases and have the potential for broader application in plant protection. Here, we present a protocol that outlines techniques for preparing dsRNA and spraying it directly to control fungal diseases. This protocol offers a practical and effective solution for managing plant diseases and has the potential to be widely applied in disease management.

Identification of a Novel Streptomyces Species for Management of Plant Disease

Native isolates of groundnut stem rot casual organism, Sclerotium rolfsii Sacc. Were collected from major groundnut growing areas of Tamil Nadu. Selected isolates were screened, characterized and indentified the virulent isolate (GNSR1). Several native bacterial and fungal antagonists were isolated against GNSR1. Two antagonistic isolates, viz., GNRAJK1 and GNRAVR14, were found to have antagonistic effects on GNSR1. Morphology and spore structure of isolated antagonists, GNRAJK1 and GNRAVR14, were studied under Light microscopy, Biochemical test, Thin layer chromatography and Biolog analysis. It confirmed the group of micro organisms as Streptomyces based on gram staining, medium specific growth, visual morphological characters, cell wall amino acid studies and spore forming chraracters. The genus and species level of the antagonists were identified by Fatty Acids Methyl Esters (FAME) Analysis. The isolate GNRAJK1 had a SIM index of 0.007 and was identified as Streptomyces violaceusniger, and GNRAVR14 had a SIM index of 0.013 and was identified as Streptomyces exfoliatus.

Application of Indigenous Technological Knowledge (ITK) for Plant Disease Management in Tamil Nadu, India

Most of the farmers in our country highly depend on chemical pesticides and fungicides to control pests and diseases in agriculture and horticultural crops. Abundant usage of these pesticides in crop fields causes harmful effects to human beings as well as to other living organisms. The harmful effects of these chemicals brings the emergency call for ecofriendly and hazard free sustainable agriculture. Indigenous technological knowledge (ITK) originates from local, rural communities and it can play an important role in organic agriculture. The ITKs are eco-friendly and compatible with various agricultural management practices particularly pest and disease management. Application of ITK in crop management, contributing towards chemical residue-free agricultural products. The farmers of Tamil Nadu state in India profusely use the chemical pesticides and fungicides to control crop pests and diseases even though most districts in Tamil Nadu have their own ITK practices with respect to location specificity. Hence, an attempt has been made to document some of the significant and effective ITKs followed by the farmers in Tamil Nadu for the management of crop diseases. This paper contains an overview of Indigenous Knowledge in Plant diseases management to help researchers in the future.

Evaluating the Interaction between Arbuscular Mycorrhizal Fungi (AMF) and Plant Pathogens

The presence of arbuscular mycorrhizal fungi (AMF) in the rhizosphere has been shown to exert a substantial influence on plant disease resistance. The colonization of AMF induces a cascade of defense responses in plants, resulting in heightened resistance to pathogen invasion. The current study unveils the essential role of AMF in initiating systemic defense responses in plants. When plants undergo colonization by AMF, they initiate a variety of molecular and biochemical mechanisms that enhance their immune system. These systemic defense responses equip the plant with the ability to both withstand invading pathogens and ready neighboring uninfected tissues for potential future attacks. In addition, the establishment of AMF in the roots can induce physical alterations in the root architecture, thereby increasing the difficulty for pathogens to infiltrate and infect plants. While there have been notable advancements in understanding the overall impact of AMF colonization on plant disease resistance, further investigation is needed. Future investigations should delve into the mechanisms of AMF colonization on plant disease resistance, with a particular emphasis on elucidating the signaling pathways and biochemical factors that trigger systemic defense responses. This will offer valuable insights into the molecular foundation of plant immunity and aid in the development of precise disease management strategies. AMF can also serve as biocontrol agents for sustainable management of plant diseases, thereby decreasing dependency on chemical pesticides and encouraging environmentally-conscious practices. The efficiency of AMF colonization and the expression of plant defense responses can be significantly altered by environmental factors, such as soil conditions and nutrient availability. Comprehending these factors will facilitate the formulation of efficient management tactics to enhance biotic interactions in agricultural systems.

Role of Modern Technologies in Plant Disease Management: A Comprehensive Review of Benefits, Challenges, and Future Perspectives

This thorough analysis examines how contemporary technologies are altering the control of plant diseases. The introduction gives a general overview of the situation, explaining the historical context and the need for modern solutions. The paper then explores the various advantages that contemporary technologies offer for managing plant diseases, emphasizing developments in methods for detection, monitoring, and control. But putting these technologies into practice is not without its difficulties; the third segment methodically looks at these issues, covering everything from infrastructure and knowledge gaps to financial consequences.
 The fourth section highlights the effective uses of contemporary technologies to control plant diseases through a detailed analysis of case cases. These real-world instances highlight the effectiveness and significance of technology-based treatments. After that, the article turns its attention to the current situation and probable future developments, providing insights into how modern technologies are now being used to manage plant diseases and projecting future trends and developments.
 The evaluation comes to a close in the last section with helpful suggestions for incorporating and utilizing contemporary technologies. Actionable techniques are given to practitioners, policymakers, and stakeholders to maximize the advantages of these technological interventions while overcoming obstacles.
 In the age of contemporary technologies, this review is an invaluable tool for scholars, decision-makers, and business experts navigating the ever-changing field of plant disease management.

Lipopeptides: Powerful Antifungal Compounds Produced by Bacillus Species: A Review

Phytopathogens affect the crops each year and hurt the economy of the country. Researchers’ main concern is investigating biocontrol agents’ potential as alternative sources to combat diseases. The Bacillus genus produced various plant growth-promoting compounds useful for managing plant diseases. These agents are harmless to the environment and proven effective antagonists against pathogens. The lipopeptides extracted by Bacillus spp. are effective germ killers, and the most notable among them are iturins, surfactin, fengycin, bacillomycin, and plipastatin, which exhibit potent antibacterial action against a wide variety of phytopathogens. Lipopeptides are non-toxic, biodegradable, and friendly to the natural world. Different lipopeptides have been reviewed for their function and mechanism of action in biocontrol in literature. The purpose of this review is to analyze the previous and recent research work and the mechanisms that involved for the management of disease by lipopeptides produced by Bacillus genus