Search Results (271)

Sclerotinia sclerotiorum (S. sclerotiorum), a necrotrophic phytopathogen, causes sclerotinia stem rot (SSR) in many crops like oilseed rape, resulting in severe economic losses. Developing eco-friendly compound fungicides has become a critical research priority. This study explored the combination of sodium selenite and cuminic acid to screen for the optimal mixing ratio and investigate its inhibitory effects and mechanisms against S. sclerotiorum. The results demonstrated that synergistic effects were observed with a 1:3 combination ratio of sodium selenite to cuminic acid. After treatment with the selenium compound agent, ultrastructural observations revealed that the hyphae of S. sclerotiorum became severely shriveled, deformed, and twisted. The agent significantly reduced oxalic acid production and the activities of polymethylgalacturonide (PMG) and carboxymethylcellulose enzymes (Cx), while increasing the exocytosis of nucleic acids and proteins from the mycelium. Foliar application of the selenium compound agent significantly reduced lesion areas in rapeseed. Combined with the results of transcriptome sequencing, this study suggests that the compound agent effectively inhibits the growth of S. sclerotiorum by disrupting its membrane system, reducing the activity of cell wall-degrading enzymes, and suppressing protein synthesis, etc. This research provides a foundation for developing environmentally friendly and effective fungicides to control S. sclerotiorum. Full article

The potential of Trichoderma fungi as biocontrol agents has not yet been fully explored, as there is a large repertoire of inter- and intra-species variation in their phytopathogenic antagonistic effects due to different adaptations of individual Trichoderma strains. In the present study, we investigated the biocontrol efficacy of eight native isolates of Trichoderma spp. against the soilborne phytopathogens Sclerotinia sclerotiorum and Rhizoctonia solani and a representative of the Mucoromycota, Phycomyces blakesleeanus. An in vitro dual culture test showed a complete (100%) inhibition of S. sclerotiorum and P. blakesleeanus by each tested Trichoderma strain and a high (80–100%) inhibition of R. solani. The crude chloroform extracts, whose peptide contents were confirmed by thin-layer chromatography, caused a concentration-dependent reduction in the growth of the target fungi, with inhibition comparable to the effect of the peptaibol standard alamethicin. Despite the differences between fungi from the phyla Basidiomycota, Ascomycota, and Mucoromycota, their inhibition by alamethicin followed the same dose–response dependence. The growth inhibition of P. blakesleeanus induced by Trichoderma extracts was characterized by a significantly increased activity of antioxidative defense enzymes. Both variants of biocontrol agents, the native strains of Trichoderma spp. and their extracts, are efficient in controlling fungal growth and should be considered for the development of new potent bioformulations applicable in agriculture. Full article

Soilborne diseases cause losses of 45–70% in faba bean in Ethiopia. Studies were undertaken to define soilborne pathogens and their complexes in Ethiopia. First, the severity of root rot was assessed in 150 field sites across seven Ethiopian regions. Soil samples were collected, and the DNA of 29 pests and pathogens was quantified using a commercial quantitative PCR (qPCR) soil testing service. There was a very high incidence rate of Macrophomina phaseolina, as well as Pythium clades F and I. The other detected species in order of incidence included Fusarium redolens, Rhizoctonia solani, Aphanomyces euteiches, Phytophthora megasperma, Sclerotinia sclerotiorum and S. minor, and Verticillium dahliae, as well as low levels of Thielaviopsis basicola. Five anastomosis groups (AG) of R. solani, namely AG2.1, AG2.2, AG3, AG4, and AG5, were detected, of which AG2.2 and AG4 were most prevalent. We believe this is the first report of occurrence for Ethiopia of A. euteiches, Ph. megasperma, T. basicola, and the five AGs for R. solani. There were very high incidence rates of the foliar pathogens Botrytis cinerea, B. fabae, Didymella pinodes, and Phoma pinodella and of the nematode Pratylenchus thornei, followed by P. neglectus and P. penetrans. The root rot severity and distribution varied significantly across regions, as well as with soil types, soil pH, and soil drainage. Subsequently, metabarcoding of the soil DNA was undertaken using three primer pairs targeting fungi (ITS2), Fusarium species (TEF1 α), and Oomycetes (ITS1Oo). The ITS2 and TEF1α primers emphasized F. oxysporum as the most abundant soilborne fungal pathogen and highlighted F. ananatum, F. brachygibbosum, F. brevicaudatum, F. clavum, F. flagelliforme, F. keratoplasticum, F. napiforme, F. nelsonii, F. neocosmosporiellum, F. torulosum, and F. vanettenii as first reports of occurrence for Ethiopia. The ITS1Oo primer confirmed Pythium spp. as the most prevalent of all Oomycetes. Full article

Nine chaetoglobosins (1–9) including five previously undescribed ones (1–5) were obtained from the culture broth of an endophytic fungus (Chaetomium sp. UJN-EF006) isolated from the leaves of Vaccinium bracteatum. The structures of these fungal metabolites were elucidated by spectroscopic methods including mass spectroscopy, nuclear magnetic resonance, single crystal X-ray crystallography, and electronic circular dichroism. To accelerate the development of novel fungicides, all of the isolated chaetoglobosins were evaluated for their antifungal activity against two crop pathogens, Botrytis cinerea and Sclerotinia sclerotiorum. The assay results revealed that chaetoglobosins 2, 6, 7, and 9 possessed a significant fungicidal effect against B. cinerea, with EC₅₀ values all below 10 μg/mL. Particularly, the most potent compound, 7, was 175- and 96-fold as active as the commercially available fungicides carbendazim (EC₅₀ 70.11 μg/mL) and azoxystrobin (EC₅₀ 39.02 μg/mL), respectively. A further observation under scanning electron microscope indicated that compound 2 could markedly impair the fungal hyphae of B. cinerea. The study demonstrates that the chaetoglobosins had excellent in vitro antifungal activities against B. cinerea. Full article

Sclerotinia sclerotiorum, known as a typical necrotrophic pathogenic fungus, exhibits a complex pathogenic mechanism. Research on S. sclerotiorum has primarily focused on oxalic acid, pathogenicity-related enzymes, and secreted proteins. In this study, we identified a transcription factor, SsSR (S. sclerotiorum Sterol-Related transcription factor), which regulates S. sclerotiorum infection by modulating virulence through ergosterol biosynthesis. We characterized the transcriptional activity of SsSR and its downstream target gene, SsCYP51. SsSR undergoes phosphorylation induced by the host plant, subsequently regulating the expression of SsCYP51. The deletion of SsSR or SsCYP51 does not affect the growth or acid production of S. sclerotiorum, but it leads to a reduction in ergosterol, significantly diminishing virulence and impairing the stress tolerance of the hyphae. In summary, this study identifies a transcription factor, SsSR, that specifically regulates the virulence of S. sclerotiorum. SsSR upregulates the expression of SsCYP51 through phosphorylation during the infection phase, leading to the synthesis of ergosterol, which enhances hyphal stress tolerance and thereby promotes infection. Full article

Grapevine (Vitis vinifera) is a key crop in Mediterranean agriculture, now increasingly threatened by Xylella fastidiosa subsp. Fastidiosa (Xff), the causal agent of Pierce’s disease. This study investigated: (1) the diversity of culturable fungal endophytes in the xylem sap of naturally Xff-infected grapevines, and (2) the interaction between Xff and the pathogenic fungus Sclerotinia sclerotiorum identified in the sap. The xylem sap was collected from Cabernet Sauvignon vines in Mallorca, Spain, and fungal communities were characterized using culture-dependent methods. Both beneficial fungi (e.g., Aureobasidium pullulans, Rhodotorula mucilaginosa) and pathogenic species (e.g., S. sclerotiorum, Cladosporium sp., Alternaria alternata, and the Phoma complex) were isolated from both Xff-positive and Xff-negative plants, indicating similar community profiles. Although limited by small sample size, these findings offer preliminary evidence of complex ecological interactions between Xff and the xylem-associated mycobiota, with potential implications for grapevine health and disease development under varying environmental and management conditions. Further experiments under controlled conditions revealed that grapevines co-inoculated with Xff and S. sclerotiorum showed increased disease severity, suggesting a synergistic interaction. These preliminary results highlight the complex interplay between Xff and the fungal endophytic microbiome, which may modulate grapevine susceptibility depending on environmental and management conditions. Full article

Sclerotinia sclerotiorum is a globally distributed fungal pathogen responsible for significant agricultural losses across a wide range of crops. This study aimed to develop polymorphic simple sequence repeat (SSR) markers by whole-genome resequencing of three Korean isolates and a public reference genome. A total of 16,885 SSR motifs were identified, of which 368 overlapped with polymorphic insertion–deletion (InDel) sites across the four genomes. From these, 12 SSR markers were selected based on polymorphism information content and amplification quality. Validation across the 28 isolates in Korea revealed high levels of genotypic diversity, suggesting that each isolate is a unique haplotype, although S. sclerotiorum is homothallic and clonally propagated. This multi-genome approach provides robust resources for genotyping, molecular diagnostics, and epidemiological surveillance of S. sclerotiorum. Full article

Rapeseed (Brassica napus) is an essential oil resource, but its yield can be significantly compromised by Sclerotinia sclerotiorum (S. sclerotiorum) infection. Due to the absence of rapeseed strains that are highly or completely immune to S. sclerotiorum, enhancing rapeseed resistance through genetic approaches is challenging. In this study, we developed a novel method to enhance rapeseed resistance to S. sclerotiorum using β-ocimene. Our results demonstrated that β-ocimene treatment significantly strengthened the defense capabilities of rapeseed. β-ocimene treatment can simultaneously activate multiple defense-related signaling pathways, including jasmonic acid signaling, salicylic acid signaling, and MAPK signaling, in rapeseed, while also inducing the accumulation of secondary metabolites coniferyl aldehyde—a key secondary metabolite in the phenylpropanoid pathway critical for plant defense responses. Furthermore, applying coniferyl aldehyde to the leaves of rapeseed can remarkably enhance its resistance to sclerotinia disease. Collectively, these findings confirm that β-ocimene activates the defense system of rapeseed, elevates the content of coniferyl aldehyde, and thereby enables rapeseed to effectively combat sclerotinia disease. The metabolomics data are available via MetaboLights under the identifier MTBLS12510. In conclusion, this study not only uncovers the mechanism by which β-ocimene induces rapeseed resistance to sclerotinia disease but also presents a novel approach for its prevention and control. Full article

C2H2 zinc finger (C2H2-ZF) transcription factors, characterized by the presence of a conserved ZnF-C2H2 domain, are widespread among plant-pathogenic fungi such as Magnaporthe oryzae, Fusarium graminearum, and Sclerotinia sclerotiorum and have critical roles in the regulation of fungal growth, development, stress adaptation, and secondary metabolism. However, little is known about the presence and roles of C2H2-ZF transcription factors in Setosphaeria turcica (syn. Exserohilum turcicum), the causal agent of northern corn leaf blight. To address this gap, we identified the complete set of C2H2-ZF transcription factors in the S. turcica genome and characterized their structural characteristics, physicochemical properties, and protein–protein interaction network. We then used RNA sequencing to profile their expression dynamics during fungal development and host infection. The 27 S. turcica C2H2-ZF proteins were classified into three major subfamilies and contained six conserved motifs. All 27 genes were transcribed during 5 stages of fungal development, and 24 were expressed during the infection of susceptible maize, suggesting that they function in both fungal growth and pathogenesis. This study represents the first systematic characterization of C2H2-ZF proteins in S. turcica, offering insight into their potential roles in pathogenicity and establishing a foundation for future functional studies of individual family members. Full article

Sclerotinia sclerotiorum is a devastating fungal pathogen that can colonize numerous crops. Despite its economic importance, the regulation of its development and pathogenicity remains poorly understood. From a forward genetic screen in S. sclerotiorum, six UV mutants were identified with loss-of-function mutations in SsATG1, SsATG2, SsATG4, SsATG5, SsATG9, and SsATG26. Functional validation through gene knockouts revealed that each ATG is essential for sclerotia formation, although the morphology of appressoria was not significantly altered in the mutants. Different levels of virulence attenuation were observed among these mutants. Autophagy, monitored using GFP-ATG8, showed dynamic activities during sclerotia development. These findings suggest that macroautophagy and pexophagy contribute to sclerotia maturation and virulence processes. Future work will reveal how autophagy controls target organelle or protein turnover to regulate these processes. Full article

Brassica napus is one of the most extensively cultivated oilseed crops in China, but its yield is significantly impacted by stem rot caused by Sclerotinia sclerotiorum. Receptor-like proteins (RLPs) and receptor-like kinases (RLKs) play essential roles in plant–pathogen interactions; however, their regulatory mechanisms remain largely unknown in B. napus. In this study, we investigated the function of the leucine-rich repeat receptor-like protein BnaRLP-G13-1 in Brassica napus immunity. Previous observations indicated that B. napus plants expressing BnaRLP-G13-1 exhibited enhanced resistance to Sclerotinia sclerotiorum. We hypothesized that BnaRLP-G13-1 mediates pathogen recognition and immune signaling. To test this, we employed mitogen-activated protein kinase (MAPK) activity assays, transgenic overexpression analyses, and pathogen infection assays. Our results demonstrated that BnaRLP-G13-1 recognizes the conserved necrosis- and ethylene-inducing peptide Ssnlp24_SsNEP2 derived from S. sclerotiorum, triggering MAPK cascades and subsequent immune responses. Furthermore, protein interaction studies revealed that BnaRLP-G13-1 physically interacts with the receptor-like kinase BnaSOBIR1, which is essential for full antifungal defense activation. These results elucidate the molecular basis of BnaRLP-G13-1-mediated immunity, providing insights into improving disease resistance in oilseed crops. Full article

With the long-term use of certain types of traditional chemical fungicides, phytopathogen resistance and environmental pollution have made the application of these fungicides face unprecedented challenges. Therefore, using the low toxicity and structural diversity of natural product analogs to develop alternatives has become an important tactic to improve control efficiency and reduce pathogen resistance, as well as environmental risks. In this study, thirty-eight rhein derivatives were synthesized after our continuous efforts aiming to discover new anthraquinone-based antifungal agents. Their structures were characterized by ¹H-NMR, ¹³C-NMR and high-resolution mass spectrometry. The antifungal activities of rhein derivatives were first evaluated against four phytopathogenic fungi. The bioassay results indicated that most derivatives exhibited good antifungal activity against Rhizoctonia solani at 0.5 mM in vitro. Compounds 3e, 3j, 4a, 9d and 10f showed potent activities against R. solani, with inhibition rates over 50% at a low concentration of 0.2 mM in vitro. In particular, compound 10a strongly inhibited the growth of Sclerotinia sclerotiorum, Fusarium graminearum and P. capsica, with EC₅₀ values of 0.079 mM, 0.082 mM and 0.134 mM, respectively, which are comparable to the commercial biofungicide phenazine-1-carboxylic acid (PCA). An in vivo study showed that 10a presented excellent curative and protective activities (92.1% and 91.1%, 0.2 mM) against wheat powdery mildew. The phytotoxicity results indicated that rhein amino acid derivatives could significantly eliminate phytotoxicity to rice and rape and could be safely used in these two crops. The resistance development assay indicated that these rhein derivatives could effectively avoid the risk of resistance development in these two strains of fungi, R. solani and S. sclerotiorum. In conclusion, rhein derivatives can be used for the development of potential agricultural fungicides. Full article

The necrotrophic pathogen Sclerotinia sclerotiorum is widely distributed and infects a broad range of hosts, making it one of the most economically damaging plant pathogens. This study demonstrated that pyrimethanil, an anilinopyrimidine fungicide, exhibited potent activity against S. sclerotiorum, with EC₅₀ values ranging from 0.411 to 0.610 μg/mL. Four highly pyrimethanil-resistant mutants were obtained through chemical taming, with EC₅₀ values of 7.247 to 24.718 μg/mL. These mutants exhibited significantly reduced mycelial growth, sclerotia production, and pathogenicity compared to their wild-type parental isolates, indicating that pyrimethanil resistance suffered a fitness penalty in S. sclerotiorum. Notably, three mutants (DDJH-Pyri-R1, DDJH-Pyri-R3, and DDJH-Pyri-R4), completely lose the capacity to infect detached tomato leaves. Point mutations that cause amino acid changes in the predicted sequence of cystathione-γ synthase (CGS) and cystathione-β lyase (CBL), encoded by SsCGS1 and SsCGS2, were identified in three mutants. However, one mutant (DDJH-Pyri-R2) showed no mutations in these genes, suggesting an alternative resistance mechanism. Molecular docking revealed that mutations in SsCGS1-R3, SsCGS1-R4, and SsCGS2-R1 reduced the binding affinity between pyrimethanil and SsCGSs. No cross-resistance was observed between pyrimethanil and other commonly used fungicides, including carbendazim, fludioxonil, prochloraz, tebuconazole, pyraclostrobin, boscalid, fluazinam, and cyprodinil. These findings provide valuable insights for designing resistance inhibitors and suggest that pyrimethanil has significant potential for controlling soybean sclerotinia stem rot (SSR) caused by S. sclerotiorum. Full article

Sclerotinia sclerotiorum is a globally widespread and vast destructive plant pathogenic fungus that causes significant yield losses in crops. Due to the lack of effective resistant germplasm resources, the control of diseases caused by S. sclerotiorum largely relies on chemical fungicides. However, excessive use of these chemicals not only causes environmental concerns but also leads to the increased development of resistance in S. sclerotiorum. In contrast, trans-kingdom sRNA silencing-based technologies, such as host-induced gene silencing (HIGS) and spray-induced gene silencing (SIGS), offer novel, effective, and environmentally friendly methods for the management of S. sclerotiorum infection. This review summarizes recent advances in the identification of S. sclerotiorum pathogenic genes, target gene selection, categories, and application of trans-kingdom RNA interference (RNAi) technologies targeting this pathogen. Although some challenges, including off-target effects and the efficiency of external sRNA uptake, exist, recent findings have proposed solutions for further improvement. Combined with the latest developments in CRISPR/Cas gene editing and other technologies, trans-kingdom RNAi has significant potential to become a crucial tool in the control of sclerotinia stem rot (SSR), mitigating the impact of S. sclerotiorum on crop production. Full article

Previous research has unearthed the integration of the coat protein (CP) gene from alphapartitivirus into plant genomes. Nevertheless, the prevalence of this horizontal gene transfer (HGT) between partitiviruses and cellular organisms remains an enigma. In our investigation, we discovered a novel partitivirus, designated Sclerotinia sclerotiorum alphapartitivirus 1 (SsAPV1), from a hypovirulent strain of Sclerotinia sclerotiorum. Intriguingly, we traced homologs of the SsAPV1 CP to plant genomes, including Helianthus annuus. To delve deeper, we employed the CP and RNA-dependent RNA polymerase (RdRP) sequences of partitiviruses as “bait” to search the NCBI database for similar sequences. Our search unveiled a widespread occurrence of HGT between viruses from all five genera within the family Partitiviridae and other cellular organisms. Notably, numerous CP-like and RdRP-like genes were identified in the genomes of plants, protozoa, animals, fungi, and even, for the first time, in an archaeon. The majority of CP and RdRP genes were integrated into plant and insect genomes, respectively. Furthermore, we detected DNA fragments originating from the SsAPV1 RNA genome in some subcultures of virus-infected strains. It suggested that SsAPV1 RdRP may possesses reverse transcriptase activity, facilitating the integration of viral genes into cellular organism genomes, and this function requires further confirmation. Our study not only offers a hypovirulence-associated partitivirus with implications for fungal disease control but also sheds light on the extensive integration events between partitiviruses and cellular organisms and enhances our comprehension of the origins, evolution, and ecology of partitiviruses, as well as the genome evolution of cellular organisms. Full article