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Life cycle and signs of infection of Sclerotinia sclerotiorum in soybean. The fungus has a monocyclic life cycle and does not produce secondary inoculum. It forms a survival structure known as
Source publication
Sclerotinia sclerotiorum (Lib.) de Bary is a broad host-range fungus that infects an inclusive array of plant species and afflicts significant yield losses globally. Despite being a notorious pathogen, it has an uncomplicated life cycle consisting of either basal infection from myceliogenically germinated sclerotia or aerial infection from ascospor...
Contexts in source publication
Context 1
... there is only one cycle of inoculum production during the course of infection, S. sclerotiorum is a simple monocyclic pathogen (Figure 2). The S. sclerotiorum lifecycle is primarily anchored by the formation of sclerotium. ...
Context 2
... are able to germinate, even invade host tissues, and cause compatible infections only when dead or senescent tissues are colonized saprotrophically before infecting healthy tissues [20]. In the field, this is typically done by colonizing leaves and flower petals that have senesced, damaged, or abscised but are still in physical contact with uninfected healthy host tissue ( Figure 2). Mycelial growth from sclerotia on the soil surface can also initiate infection. ...
Context 3
... germinated hyphae colonize dead organic matter and then infect neighboring alive plants [21]. The life cycle is completed by forming sclerotia outside or inside hollow stems, flowers, buds, and fruits that have been colonized by the fungus (Figure 2). Due to the extended soil survival of sclerotia, even in adverse conditions, controlling white mold is difficult [22]. ...
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Coccidioidomycosis (CM) can manifest as respiratory and disseminated diseases that are caused by dimorphic fungal pathogens, such as Coccidioides species. The inhaled arthroconidia generated during the saprobic growth phase convert into multinucleated spherules in the lungs to complete the parasitic lifecycle. Research on coccidioidal virulence and...
Citations
... Evaluation of diverse accessions has identified genotypes with lower severity values on leaves, pods and Areas Under the Disease Progress Curve (AUDPC), offering valuable genetic resources for future CBB resistance breeding programs (Tumsa et al., 2020). Sclerotinia sclerotiorum induces Sclerotinia stem rot in soybeans and resistance to this necrotrophic fungal pathogen is linked to early jasmonate accumulation, increased scavenging ability and reprogramming of the phenylpropanoid pathway (Ranjan et al., 2019;Hossain et al., 2023). Host resistance is not limited to pathogens, but also extends to protection against pests. ...
... However, many previous reports have indicated the difficulty in breeding and developing drop-resistant germplasm with commercially desirable traits (Subbarao 1998;Simko et al. 2023). On the other hand, enduring dormant sclerotia to hard conditions for long periods makes applying crop rotation an infeasible method (Hossain et al. 2023). Also, the excessive use of chemicals shows side effects that pose a threat to the environment and health ( Kumar et al. 2022). ...
Controlling the hazard of sclerotia produced by the Sclerotinia sclerotiorum is very complex, and it is urgent to adopt an effective method that is harmonious environmentally to control the disease. Among the six isolates isolated from the rhizosphere of lettuce, the isolate HZA84 demonstrated a high activity in its antagonism towards Sclerotinia sclerotiorum in vitro, and produces siderophore. By amplification of internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF1-α), and RNA polymerase II subunit (RPB2) genes, the isolate HZA84 was identified as Trichoderma asperellum, which was confirmed by analysis of phylogenetic tree. The Scanning electron microscope monitoring detected that the isolate HZA84 spread over the sclerotial surface, thus, damaging, decomposing, and distorting the globular cells of the outer cortex of the sclerotia. The Real-time polymerase chain reaction (RT-qPCR) analysis disclosed the overexpression of two genes (chit33 and chit37) encoding the endochitinase in addition to one gene (prb1) encoding the proteinase during 4 and 8 days of the parasitism behavior of isolate HZA84 on the sclerotia surface. These enzymes aligned together in the sclerotia destruction by hyperparasitism. On the other hand, the pots trial revealed that spraying of isolate HZA84 reduced the drop disease symptoms of lettuce. The disease severity was decreased by 19.33 and the biocontrol efficiency was increased by 80.67% within the fourth week of inoculation. These findings magnify the unique role of Trichoderma in disrupting the development of plant diseases in sustainable ways.
... Mutants of F. verticillioides also exhibited altered growth at alkaline pH (Flaherty et al. 2003). Similarly, the MAPK signalling cascade plays a central role in S. sclerotiorum pathogenesis and sclerotial formation (Hossain et al. 2023). SsSmk1 encodes a conserved Erk-type MAPK, which is activated by OA-mediated acidic pH and is involved in cAMP signalling and implicated in sclerotial development (Chen et al. 2004;Tian et al. 2023). ...
Main conclusion
The study evaluates the potential of Spray-Induced Gene Silencing and Host-Induced Gene Silencing for sustainable crop protection against the broad-spectrum necrotrophic fungus Sclerotinia sclerotiorum.
Abstract
Sclerotinia sclerotiorum (Lib.) de Bary, an aggressive ascomycete fungus causes white rot or cottony rot on a broad range of crops including Brassica juncea. The lack of sustainable control measures has necessitated biotechnological interventions such as RNA interference (RNAi) for effective pathogen control. Here we adopted two RNAi-based strategies—Spray-Induced Gene Silencing (SIGS) and Host-Induced Gene Silencing (HIGS) to control S. sclerotiorum. SIGS was successful in controlling white rot on Nicotiana benthamiana and B. juncea by targeting SsPac1, a pH-responsive transcription factor and SsSmk1, a MAP kinase involved in fungal development and pathogenesis. Topical application of dsRNA targeting SsPac1 and SsSmk1 delayed infection initiation and progression on B. juncea. Further, altered hyphal morphology and reduced radial growth were also observed following dsRNA application. We also explored the impact of stable dsRNA expression in A. thaliana against S. sclerotiorum. In this report, we highlight the utility of RNAi as a biofungicide and a tool for preliminary functional genomics.
... The main roles of oxalic acid in the pathogenesis of S. sclerotiorum are the acidification of the environment in the middle lamellae, its function as a calcium ion chelating agent, and enhancement of the activities of cell wall depolymerising enzymes. Oxalic acid interacts with the ROS generating system and affects the host redox environment, thus lowering the response of the host defence system (Hossain et al. 2023;McCaghey et al. 2019). It has also been hypothesised that oxalic acid protects S. sclerotiorum mycelium from the toxic effects of excess calcium ions in the infection zone (Heller and Witt-Geiges 2013). ...
Oxalic acid and oxalates are secondary metabolites secreted to the surrounding environment by fungi, bacteria, and plants. Oxalates are linked to a variety of processes in soil, e.g. nutrient availability, weathering of minerals, or precipitation of metal oxalates. Oxalates are also mentioned among low-molecular weight compounds involved indirectly in the degradation of the lignocellulose complex by fungi, which are considered to be the most effective degraders of wood. The active regulation of the oxalic acid concentration is linked with enzymatic activities; hence, the biochemistry of microbial biosynthesis and degradation of oxalic acid has also been presented. The potential of microorganisms for oxalotrophy and the ability of microbial enzymes to degrade oxalates are important factors that can be used in the prevention of kidney stone, as a diagnostic tool for determination of oxalic acid content, as an antifungal factor against plant pathogenic fungi, or even in efforts to improve the quality of edible plants. The potential role of fungi and their interaction with bacteria in the oxalate-carbonate pathway are regarded as an effective way for the transfer of atmospheric carbon dioxide into calcium carbonate as a carbon reservoir.
... Sclerotinia sclerotiorum (Lib.) de Bary, a notorious necrotrophic plant pathogenic fungus, has a complete life cycle and infection cycle with extremely wide distribution, causing blight, stem and crown rots of numerous crops [1][2][3][4]. S. sclerotiorum is widely distributed in warm and arid regions and can infect various plants, including oilseed crops such as soybean and rapeseed, as well as ornamental plants such as marigold and tulip [5]. Polymorphism is a remarkable characteristic of S. sclerotiorum which produces compound appressoria, sclerotia, apothecium and ascospore in the process of morphological differentiation [2,4,6]. ...
APSES (Asm1p, Phd1p, Sok2p, Efg1p, and StuAp) family transcription factors play crucial roles in various biological processes of fungi, however, their functional characterization in phytopathogenic fungi is limited. In this study, we explored the role of SsStuA, a typical APSES transcription factor, in the regulation of cell wall integrity (CWI), sclerotia formation and pathogenicity of Sclerotinia sclerotiorum, which is a globally important plant pathogenic fungus. A deficiency of SsStuA led to abnormal phosphorylation level of SsSmk3, the key gene SsAGM1 for UDP-GlcNAc synthesis was unable to respond to cell wall stress, and decreased tolerance to tebuconazole. In addition, ΔSsStuA was unable to form sclerotia but produced more compound appressoria. Nevertheless, the virulence of ΔSsStuA was significantly reduced due to the deficiency of the invasive hyphal growth and increased susceptibility to hydrogen peroxide. We also revealed that SsStuA could bind to the promoter of catalase family genes which regulate the expression of catalase genes. Furthermore, the level of reactive oxygen species (ROS) accumulation was found to be increased in ΔSsStuA. In summary, SsStuA, as a core transcription factor involved in the CWI pathway and ROS response, is required for vegetative growth, sclerotia formation, fungicide tolerance and the full virulence of S. sclerotiorum.
... Evaluation of diverse accessions has identified genotypes with lower severity values on leaves, pods and Areas Under the Disease Progress Curve (AUDPC), offering valuable genetic resources for future CBB resistance breeding programs (Tumsa et al., 2020). Sclerotinia sclerotiorum induces Sclerotinia stem rot in soybeans and resistance to this necrotrophic fungal pathogen is linked to early jasmonate accumulation, increased scavenging ability and reprogramming of the phenylpropanoid pathway (Ranjan et al., 2019;Hossain et al., 2023). Host resistance is not limited to pathogens, but also extends to protection against pests. ...
... In this work, four isolates affiliated with the genera Pseudomonas, Cupriavidus, Acinetobacter, and Providencia showed strong antifungal activity against the S. sclerotiorum strain. This fungus is among the world's most virulent and widespread plant-killing organisms (Hossain et al., 2023). S. sclerotiorum possesses profound parasitic abilities and can colonize nearly all plant tissues with its mycelia through direct penetration of the plant or by invading wounds. ...
Plant growth–promoting rhizobacteria (PGPR) can promote plant growth and development with several beneficial effects, especially in challenging environmental conditions, such as the presence of toxic contaminants. In this study, 49 isolates obtained from Trifolium sp. nodules growing on a Pb/Zn mine site were characterized for PGP traits including siderophores production, phosphate solubilization, extracellular enzymes production, and antifungal activity. The isolates were also screened for their ability to grow at increasing concentrations of NaCl and heavy metals, including lead, zinc, cobalt, copper, nickel, cadmium, and chromium. The findings of our study indicated that isolates Cupriavidus paucula RSCup01-RSCup08, Providencia rettgeri RSPro01, Pseudomonas putida RSPs01, Pseudomonas thivervalensis RSPs03-RSPs09, and Acinetobacter beijerinckii RSAci01 showed several key traits crucial for promoting plant growth, thus demonstrating the greatest potential. Most isolates displayed resistance to salt and heavy metals. Notably, Staphylococcus xylosus RSSta01, Pseudomonas sp. RSPs02, Micrococcus yunnanensis RSMicc01, and Kocuria dechangensis RSKoc01 demonstrated a significant capacity to grow at salt concentrations ranging from 10 to 20%, and isolates including Cupravidus paucula RSCup01-RSCup08 exhibited resistance to high levels of heavy metals, up to 1300 mg/L Pb⁺⁺, 1200 mg/L Zn⁺⁺, 1000 mg/L Ni⁺⁺, 1000 mg/L Cd⁺⁺, 500 mg/L Cu⁺⁺, 400 mg/L Co⁺⁺, and 50 mg/L CrVI+. Additionally, the analysis revealed that metal-resistant genes pbrA, czcD, and nccA were exclusively detected in the Cupriavidus paucula RSCup01 strain. The results of this study provide insights into the potential of plant growth-promoting rhizobacteria strains that might be used as inoculants to improve phytoremediation in heavy metal-contaminated soils.
... The pathogenesis of S. sclerotiorum is relatively complex. Research mainly focuses on its secreted hydrolases, oxalic acid, early secretory pathways, and secreted proteins [7][8][9][10]. However, the biological function and mechanism of transcription factors (TFs) in the pathogenic process of S. sclerotiorum remain relatively understudied. ...
Sclerotinia sclerotiorum is a fungal pathogen with a broad range of hosts, which can cause diseases and pose a great threat to many crops. Fungal-specific Zn2Cys6 transcription factors (TFs) constitute a large family prevalent among plant pathogens. However, the function of Zn2Cys6 TFs remains largely unknown. In this study, we identified and characterized SsZNC1, a Zn2Cys6 TF in S. sclerotiorum, which is involved in virulence, sclerotial development, and osmotic stress response. The expression of SsZNC1 was significantly up-regulated in the early stages of S. sclerotiorum infection on Arabidopsis leaves. The target deletion of SsZNC1 resulted in reduced virulence on Arabidopsis and oilseed rape. In addition, sclerotial development ability and growth ability under hyperosmotic conditions of SsZNC1 knockout transformants were reduced. A transcriptomic analysis unveiled its regulatory role in key cellular functions, including cellulose catabolic process, methyltransferase activity, and virulence, etc. Together, our results indicated that SsZNC1, a core regulatory gene involved in virulence, sclerotial development and stress response, provides new insight into the transcription regulation and pathogenesis of S. sclerotiorum.
... S. sclerotiorum synthesizes oxalic acid, which contributes to the pathogenesis and colonization ability of the pathogen [22]. The management of S. sclerotiorum is difficult due to its capacity to form resistant sclerotia, which can remain active for years until it germinates and infects the host plant [23][24][25]. ...
Here, we are reviewing all biocontrol methods for the management of Sclerotinia sclerotiorum in Brassica species. Bacterial, fungal, and viral biocontrol agents have been used to control S. sclerotiorum. The highest biocontrol efficacies were detected via foliar spraying of bacterial cells. Some Bacillus spp. and Pseudomonas spp. allowed disease incidence inhibitions higher than 90 % under greenhouse conditions. Some biocontrol strains synthesized antifungal lipopeptides, phenazines, and volatile organic compounds, or induced disease resistance. Collectively, some biocontrol strains have been demonstrated to be suitable alternatives for S. sclerotiorum management; however, the antifungal mechanisms are unclear, limiting the optimization of the methods.
... 1,2 It is a high-incidence disease and is also the most difficult disease to control in oilseed rape production, which has a serious impact on the yield and quality of oilseed rape. 3,4 Oilseed rape at different growth stages can be infected by S. sclerotiorum, especially during the flowering phase. 5 Chemical control is still the most effective measure for management of the disease. ...
... Under appropriate conditions, the sclerotia germinate to produce apothecia, and the apothecia then eject a large number of ascospores to infect oilseed rape. 4,27 In addition, oxalic acid is an important pathogenic factor of various pathogenic fungi, and oxalic acid knockout mutants of S. sclerotiorum could not infect plants. 27,28 Natamycin inhibited the formation of sclerotia and the synthesis of oxalic acid, which indicated that natamycin could interrupt the life cycle and prevent the infection of S. sclerotiorum. ...
BACKGROUND
Sclerotinia stem rot caused by Sclerotinia sclerotiorum seriously endangers oilseed rape production worldwide, and the occurrence of fungicide‐resistant mutants of S. sclerotiorum leads to control decline. Thus, it is critical to explore new green substitutes with different action mechanisms and high antifungal activity. Herein, the activity and the action mechanism of natamycin against S. sclerotiorum were evaluated.
RESULTS
Natamycin showed potent inhibition on the mycelial growth of S. sclerotiorum, and half‐maximal effective concentration (EC50) values against 103 S. sclerotiorum strains ranged from 0.53 to 4.04 μg/mL (mean 1.44 μg/mL). Natamycin also exhibited high efficacy against both carbendazim‐ and dimethachlone‐resistant strains of S. sclerotiorum on detached oilseed rape leaves. No cross‐resistance was detected between natamycin and carbendazim. Natamycin markedly disrupted hyphal form, sclerotia formation, integrity of the cell membrane, and reduced the content of oxalic acid and ergosterol, whereas it increased the reactive oxygen species (ROS) and malondialdehyde content. Interestingly, exogenous addition of ergosterol could reduce the inhibition of natamycin against S. sclerotiorum. Importantly, natamycin significantly inhibited expression of the Cyp51 gene, which is contrary to results for the triazole fungicide flusilazole, indicating a different action mechanism from triazole fungicides.
CONCLUSION
Natamycin is a promising effective candidate for the resistance management of S. sclerotiorum. © 2023 Society of Chemical Industry.
