The antifungal activities of eleven C sub(21)-steroidal compounds isolated from Cynanchum wilfordii, together with thirty-six derivatives of caudatin and qingyangshengenin were evaluated on ...Sclerotinia sclerotiorum and other five fungal strains by the mycelium growth rate method. Four derivatives 1k, 1y, 10d, and 10j exhibited much stronger inhibitions on growth of S. sclerotiorum with IC sub(50) values of 0.0084, 0.0049, 0.0053, and 0.0034 mu M, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a serious disease of many cruciferous crops and frequently poses a threat to the sustainable and profitable production of these crops ...worldwide. Differences in seedling resistance to S. sclerotiorum across 46 diverse cruciferous genotypes from 12 different species were assessed by comparing the extent of pathogenesis on inoculated cotyledons under controlled conditions. Selections of Brassica carinata, B. incana, B. juncea, B. napus, and B. napus introgressed with B. carinata, B. nigra, B. oleracea, B. rapa var. rosularis, B. rapa var. chinensis, B. tournefortii, Raphanus raphanistrum, R. sativus, and Sinapis arvensis were tested. The average size of lesions on cotyledons 48 h post inoculation varied from 0.8 to 7.3 mm. The three most resistant genotypes with the smallest lesions were all from B. oleracea (viz., B. oleracea var. italica 'Prophet' and B. oleracea var. capitata 'Burton' and 'Beverly Hills'). Representatives of R. raphanistrum, S. arvensis, B. juncea, and B. carinata were the most susceptible to S. sclerotiorum, with the largest lesions. To our knowledge, this is the first report of high levels of resistance to S. sclerotiorum in B. oleracea at the cotyledon stage and also the first report of the host cotyledon reactions against S. sclerotiorum for all tested species except B. napus and B. juncea. The mean lesion size for B. napus introgressed with B. carinata was 5.6 mm, which is midway between the lesion size for the two parent species B. napus (5.1 mm) and B. carinata (5.8 mm). Separate genetic control for cotyledon versus mature plant resistance was demonstrated by the lack of correlation between lesion size from S. sclerotiorum on the cotyledon with the severity of disease initiated by stem inoculation or natural processes in a previous field test. On the most resistant genotypes, B. oleracea var. italica Prophet and var. capitata Burton, growth of S. sclerotiorum on the cotyledon surface prior to penetration was severely impeded, production of appressoria inhibited, and both cytoplasm shrinkage and protoplast extrusion in S. sclerotiorum hyphae prevalent. This is the first report of such resistant mechanisms in B. oleracea. Genotypes with cotyledon resistance identified in this study will be of great value not only in furthering our understanding of resistance mechanisms across different cruciferous species but also could be exploited for developing commercial crucifer cultivars with high-level resistance against S. sclerotiorum.
The white mold fungus Sclerotinia sclerotiorum is a devastating necrotrophic plant pathogen with a remarkably broad host range. The interaction of necrotrophs with their hosts is more complex than ...initially thought, and still poorly understood.
We combined bioinformatics approaches to determine the repertoire of S. sclerotiorum effector candidates and conducted detailed sequence and expression analyses on selected candidates. We identified 486 S. sclerotiorum secreted protein genes expressed in planta, many of which have no predicted enzymatic activity and may be involved in the interaction between the fungus and its hosts. We focused on those showing (i) protein domains and motifs found in known fungal effectors, (ii) signatures of positive selection, (iii) recent gene duplication, or (iv) being S. sclerotiorum-specific. We identified 78 effector candidates based on these properties. We analyzed the expression pattern of 16 representative effector candidate genes on four host plants and revealed diverse expression patterns.
These results reveal diverse predicted functions and expression patterns in the repertoire of S. sclerotiorum effector candidates. They will facilitate the functional analysis of fungal pathogenicity determinants and should prove useful in the search for plant quantitative disease resistance components active against the white mold.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•A porous CaCO3 carrier coated metal-polyphenol films was prepared for fungicide delivery.•Prochloraz-loaded carrier (PC@TA/Cu) exhibited tailored pH-responsive properties.•PC@TA/Cu ...provided sustained protection in oilseed rape against Sclerotinia disease.•Metal-polyphenol coating could improve deposition efficiency toward oilseed rape leaves.
The study of release mechanisms of pesticides with respect to environmental and biological factors facilitates improvement in pesticide use efficiencies and reduction in environmental risk. In this study, prochloraz (Pro), a highly effective fungicide, was loaded into starch-doped porous calcium carbonate (CaCO3), which was subsequently coated with a metal–phenolic film to prepare a pH-responsive delivery system (PC@TA/Cu). Results demonstrated that CaCO3 had a mean diameter of 1.55 µm and its loading capacity for Pro was ~15.2%. PC@TA/Cu microparticles show good adhesion to rapeseed oil leaves and resisted washout with simulated rainwater. The cumulative release rate of PC@TA/Cu particles at pH = 3 was 1.63 times higher than that in near-neutral pH environment for 48 h. This pH-responsive release characteristic could be associated with the oxalic acid secreted by Sclerotinia sclerotiorum. The control effect against Sclerotinia disease with 100 μg/mL of Pro content of PC@TA/Cu was 56.8% after 7 d, while that of Pro EW (emulsion in water) was 45.8%. Finally, biosafety tests showed a 4-fold reduction in the acute toxicity of PC@TA/Cu to zebrafish, compared to the that of Pro technical. The carrier (CaCO3@TA/Cu) had no significant effect on the growth of rapeseed oil seedlings. The results showed that the prepared PC@TA/Cu has long-lasting disease control capability and significantly reduced toxicity to non-target organisms, making it valuable for potential applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, a combination of Serratia nematophila L2 and Bacillus velezensis W24 was used to biocontrol Sclerotinia sclerotiorum. When the mixed ratio of L2 to W24 was 1:1, the inhibition rate on ...the growth of S. sclerotiorum was 88.1 %. To gain a large number of bacteria, the culture medium and conditions were optimized. When the medium formula involved molasses (8.890 g/L), soy peptone (6.826 g/L), and NaCl (6.865 g/L), and the culture conditions were 32 °C, inoculum 4%, rotation speed 200 rpm, and pH 7, the maximum amounts of bacterial cells obtained. In order to prepare microcapsules, spray drying conditions were optimized. These conditions included the soluble starch concentration of 30 g/100 mL, the inlet air temperature of 160 °C, and the feed flow rate of 450 mL/h. Under these optimized conditions to prepare microcapsules, the mixed strain (L2 and W24) exhibited a survival rate of 93.9 ± 0.9% and a viable bacterial count of 6.4 × 1012 cfu/g. In addition, microcapsules (GW24Ms) which contained strains L2 and W24 had good storage stability. In the pot experiment, GW24Ms could effectively reduce the disease of soybean plants and the control effect was 88.4%. Thus, the microbial agent represents a promising biocontrol solution for managing Sclerotinia in soybean.
•The GW24 (W24 and L2 strains were mixed) could inhibit the growth of Sclerotinia sclerotiorum.•The culture conditions and medium of GW24 were optimized.•The GW24 microcapsules were prepared by spray drying.•The GW24 microcapsules had great storage ability.•The GW24 microcapsules had great effects on S. sclerotiorum.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Nanotechnology applied to the agricultural sector has highlighted in recent decades, making important contributions, including systems for pest control as biogenic nanoparticles. These nanoparticles ...are used to control phytopathogens, demonstrating the need to understand its composition, mechanisms of action and toxicity. Their capping of biomolecules, derived from the organism used in the synthesis, contributes to their stability and biological activity. Ag nanoparticles were produced by the fungus Trichoderma harzianum in aqueous solutions containing silver nitrate as a precursor for the silver nanoparticles. Some of the samples were exposed to the phytopathogenic fungus Sclerotinia sclerotiorum responsible for the white mold. After preparation, a fraction of the samples was submitted to physico-chemical processes to remove organic cap layer on nanoparticles surface formed during the preparation process. In this study we determined the effect of the phytopathogenic fungus and cap removal process in the average radius, radius dispersion, number density of the nanoparticles using small angle X-ray scattering (SAXS), where we considered their almost spherical shape in aqueous solution obtained by the biogenic route. The SAXS data analyses suggest that the presence of the pathogenic fungus results in a diminution of number and total volume of Ag NPs without significant effects on average radius and radius dispersion. Our results also indicate that the physic-chemical process to remove the organic cap surrounding the Ag NPs leads to a decrease in the fraction of the smaller nanoparticles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum, is the main disease threat to oilseeds in Brassiceae, causing significant yield losses and reduction in oil content and quality. While ...the genetic mechanism underlying its lethal phenotype, particularly in B. juncea, remains largely unexplored. Transcriptome analysis revealed a large number of defense-related genes and response processes in B. napus and B. oleracea. However, similarities and differences in the defense responses to S. sclerotiorum on B. juncea are rarely reported. In the present study, we reported a B. juncea breeding line of H83 with high S. sclerotiorum resistance, which was used for transcriptome analysis compared to L36 with low resistance. A novel regulatory network was proposed to defend against S. sclerotiorum invasion in B. juncea. Upon infection of S. sclerotiorum, a series of were initiated within 12 h, and then defenses were activated to restrict the development and spread of S. sclerotiorum by inducing the massive synthesis of indole glucosinolates after 24 h. Twelve hub genes involved in the network were identified by the weighted gene co-expression network (WGCNA), which are involved in plant-pathogen interaction, signaling pathway genes, indole glucosinolate biosynthesis and cell wall formation. The hub genes were further validated by qRT-PCR. The research revealed a new resistant line of H83 against S. sclerotiorum and a different regulatory network in B. juncea, which would be beneficial for the future effective breeding of Sclerotinia-resistant varieties.
•●A Brassica juncea line showed high resistance to Sclerotinia sclerotiorum.•●Induction of the indole glucosinolate biosynthesis pathway resulted in high resistance to Sclerotinia sclerotiorum.•●Weighted gene co-expression network analysis identified 12 hub genes for resistance to Sclerotinia sclerotiorum.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mycoviruses are viruses that infect fungi, and hypovirulence-associated mycoviruses have the potential to control fungal diseases. However, it is unclear how mycovirus-mediated hypovirulent strains ...live and survive in the field, and no mycovirus has been applied for field crop protection. In this study, we found that a previously identified small DNA mycovirus (SsHADV-1) can convert its host, Sclerotinia sclerotiorum, from a typical necrotrophic pathogen to a beneficial endophytic fungus. SsHADV-1 downregulates the expression of key pathogenicity factor genes in S. sclerotiorum during infection. When growing in rapeseed, the SsHADV-1-infected strain DT-8 significantly regulates the expression of rapeseed genes involved in defense, hormone signaling, and circadian rhythm pathways. As a result, plant growth is promoted and disease resistance is enhanced. Field experiments showed that spraying DT-8 at the early flowering stage can reduce the disease severity of rapeseed stem rot by 67.6% and improve yield by 14.9%. Moreover, we discovered that SsHADV-1 could also infect other S. sclerotiorum strains on DT-8-inoculated plants and that DT-8 could be recovered from dead plants. These findings suggest that the mycoviruses may have the ability to shape the origin of endophytism. Our discoveries suggest that mycoviruses may influence the origin of endophytism and may also offer a novel strategy for disease control in which mycovirus-infected strains are used to improve crop health and release mycoviruses into the field.
A DNA mycovirus, SsHADV-1, converts its host, Sclerotinia sclerotiorum, from a cosmopolitan necrotrophic pathogen to a beneficial endophytic fungus. When grown on rapeseed, SsHADV-1-infected S. sclerotiorum can promote plant growth and enhance disease resistance. Our discoveries suggest that fungal pathogens infected with hypovirulence-associated mycoviruses can be used as plant vaccines to improve crop health and enhance yield.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mycoviruses are viruses that infect fungi and have the potential to control fungal diseases of crops when associated with hypovirulence. Typically, mycoviruses have double-stranded (ds) or ...single-stranded (ss) RNA genomes. No mycoviruses with DNA genomes have previously been reported. Here, we describe a hypovirulence-associated circular ssDNA mycovirus from the plant pathogenic fungus Sclerotinia sclerotiorum. The genome of this ssDNA virus, named Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), is 2166 nt, coding for a replication initiation protein (Rep) and a coat protein (CP). Although phylogenetic analysis of Rep showed that SsHADV-1 is related to geminiviruses, it is notably distinct from geminiviruses both in genome organization and particle morphology. Polyethylene glycol-mediated transfection of fungal protoplasts was successful with either purified SsHADV-1 particles or viral DNA isolated directly from infected mycelium. The discovery of an ssDNA mycovirus enhances the potential of exploring fungal viruses as valuable tools for molecular manipulation of fungi and for plant disease control and expands our knowledge of global virus ecology and evolution.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Sclerotinia rot is a serious disease that occurs on Zephyranthes candida . A thorough understanding of the pathogenic fungal species and understanding the biological characteristics are important for ...controlling sclerotinia . Fungal strains were isolated from the diseased leaves of Z. candida through tissue isolation. Koch’s hypothesis screened pathogenic strains by pathogenicity of healthy leaves, including re-isolation and identification. A multigene phylogenetic tree was constructed by extracting genomic DNA from pathogenic strains and measuring the nucleotide sequences at four sites, including the internal transcribed spacer (ITS), RNA polymerase II second largest subunit (RPB2), glyceraldehyde-3-phosphate dehydrogenase (G3PDH), and heat shock protein 60 (HSP60). Morphological characteristics of the fungal structures were evaluated through microscopic analysis. The growth of pathogens was observed and recorded under different pH, different temperatures, different carbon sources and different nitrogen sources to clarify their biological characteristics. Representative strains D7, D13, X4, and X15 infected Z. candida and caused sclerotinia rot. At the beginning of the culture, white flocculent fungal hyphae appeared on the potato dextrose agar (PDA) medium, and black spherical to irregular-shaped sclerotia appeared at the edge of the colony after 7 days. The diameter of the sclerotia was 2.4–8.6 mm and 0.4–0.9 mm, respectively. One sclerotium was able to germinate from 1 to 5 apothecia. Ascus were cylindrical or spindle-shaped, with a size of 110.0–120.0 × 9.2–11.6 μm. One ascus contained eight colorless, oval ascospores, with a size of 8.4–12.0 × 4.5–5.5 μm. Based on the phylogenetic tree constructed with the gene sequences for ITS, G3PDH, HSP60, and RPB2, D7 and D13 shared 99% homology with sclerotinia sclerotiorum , whereas X4 and X15 shared 99% homology with sclerotinia minor . S. sclerotiorum growth was more suitable when the culture temperature was 15°C–25°C, pH 5.0, carbon source was maltose and nitrogen source was yeast powder. S. minor growth was more suitable when the culture temperature was 15°C, pH 5.0, the carbon source was glucose, and the nitrogen source was yeast powder. The results identified the pathogens as S. sclerotiorum and S. minor . To the best of our knowledge, this is the first report of S. sclerotiorum and S. minor causing sclerotinia rot on Z. candida . We herein aimed to identify the causal agent of sclerotinia rot of Z. candida in China based on morphological characteristics, molecular identification, and pathogenicity tests. Performed the experiments on the biological characteristics, to understand the law of disease occurrence. We also evaluated methods for the effective control of this disease. Our findings provide support for further studies on the pathogenesis mechanism of sclerotinia rot.
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