Sclerotinia Sclerotiorum Research Articles

In vitro inhibition of Sclerotinia sclerotiorum mycelial growth and reduction of sclerotial viability by the volatile bioactive compounds of Brassicaceae crops.

Sclerotinia sclerotiorum is an important pathogen of a wide range of crops, with current control mostly relying on the use of fungicides. This study assessed the effect of biofumigation on in vitro inhibition of mycelial growth and reduction of sclerotial viability of Sclerotinia sclerotiorum as an attempt to seek an alternative management strategy. The effect of different biofumigant crop types to inhibit mycelial growth of ten S. sclerotiorum isolates was investigated, with Brassica juncea 'Caliente 199' being the most effective biofumigant crop. The efficacy of 'Caliente 199' to inhibit mycelial growth and reduce sclerotial viability was influenced by different crop factors. Plant tissue of 'Caliente 199' harvested at 50% or 100% flowering and adjusted to 80% (w/w) moisture resulted in greater mycelial inhibition and reduction in the sclerotial viability compared with the vegetative tissue with the same plant moisture. Mycelial inhibition and reduction of sclerotial viability were affected by tissue quantity. Whole plant tissue and shoots only resulted in a similar inhibition of mycelial growth, but whole plant tissue resulted in a greater reduction of sclerotial viability. The S. sclerotiorum isolates differed in sensitivity to the volatile bioactive compounds released by the biofumigant plant tissue. The volatile bioactive compounds released by 'Caliente 199' resulted in effective mycelial inhibition but did not kill sclerotia completely.

Discovery of Highly Efficient Novel Antifungal Lead Compounds Targeting Succinate Dehydrogenase: Pyrazole-4-carboxamide Derivatives with an N-Phenyl Substituted Amide Fragment.

Developing environmentally friendly fungicides is crucial to tackle the issue of rising pesticide resistance. In this study, a series of novel pyrazole-4-carboxamide derivatives containing N-phenyl substituted amide fragments were designed and synthesized. The structures of target compounds were confirmed by 1H NMR, 13C NMR, and HRMS, and the crystal structure of the most active compound N-(1-(4-(4-(tert-butyl)benzamido)phenyl)propan-2-yl)-3-(difluoromethyl)-N-methoxy-1-methyl-1H-pyrazole-4-carboxamide (U22) was further determined by X-ray single-crystal diffraction. The bioassay results indicated that the 26 target compounds possessed good in vitro antifungal activity against Sclerotinia sclerotiorum with EC50 values for compounds U12, U13, U15, U16, U18, U22, and U23 being 4.17 ± 0.46, 8.04 ± 0.71, 7.01 ± 0.71, 12.77 ± 1.00, 8.11 ± 0.70, 0.94 ± 0.11, and 9.48 ± 0.83 μg·mL-1, respectively, which were the similar to controls bixafen (6.70 ± 0.47 μg·mL-1), fluxapyroxad (0.71 ± 0.14 μg·mL-1), and pydiflumetofen (0.06 ± 0.01 μg·mL-1). Furthermore, in vivo antifungal activity results against S. sclerotiorum indicated that compounds U12 (80.6%) and U22 (89.9%) possessed excellent preventative efficacy at 200 μg·mL-1, which was the same as the control pydiflumetofen (82.4%). Scanning electron microscopy and transmission electron microscopy studies found that the compound U22 could destroy the hyphal morphology and damage mitochondria, cell membranes, and vacuoles. The results of molecular docking of compound U22 and pydiflumetofen with succinate dehydrogenase (SDH) indicated they interact well with the active site of SDH. This study validated our approach and design strategy to produce compounds with an enhanced biological activity as compared to the parent structure.

Tunisian Eucalyptus essential oils: exploring their potential for biological applications

This study focuses on different chemo-types of Tunisian Eucalyptus essential oils (EOs) and their potential for controlling aphids, phytopathogenic fungi, weed germination and seedling growth. The EOs, obtained from Eucalyptus astringens (Maiden) Maiden and Eucalyptus lehmannii (Schauer) Benth. leaves through hydrodistillation, were analyzed using GC-MS. The chemical analysis revealed a significant presence of oxygenated monoterpenes (ranging from 41.0% to 83.0%), primarily 1,8-cineole (ranging from 30.5% to 58.5%), and oxygenated sesquiterpenes, mainly globulol (19.0%) for E. astringens. In contrast, α-pinene (7.0%) was the second most abundant chemical class for E. lehmannii. Statistical analysis demonstrated that both EOs were effective against aphids, fungi, and weeds based on their composition. E. lehmannii showed high efficacy against aphids, causing complete mortality in Aphis fabae Scopoli and an 87.28 ± 0.65% mortality rate in Aphis nerii Fonscolombe at a concentration of 0.6 mg/mL. E. astringens exhibited antifungal activity with consistent inhibitory effects exceeding 50.59 ± 0.87% against Fusarium oxysporum Schltdl., and Sclerotinia sclerotiorum (Lib.) de Bary displayed even higher susceptibility with an inhibition rate of 83.33 ± 1.10%. Similarly, E. lehmannii inhibited fungal growth by nearly 50%, with Fusarium culmorum Schltdl. exhibiting a minimum inhibition rate of 45.59 ± 0.71%. Both EOs also displayed significant herbicidal potential by impeding weed germination and seedling growth. Sinapis arvensis L. was particularly susceptible, with complete inhibition observed at a concentration of 2 mg/mL. Overall, these findings highlight the potential application of these Eucalyptus EOs for bio-control, underscoring their diverse characteristics.

Genetic breakthroughs in the Brassica napus–Sclerotinia sclerotiorum interactions

Sclerotinia sclerotiorum (Lib.) de Bary is a highly destructive fungal pathogen that seriously damages the yield and quality of Brassica napus worldwide. The complex interaction between the B. napus and S. sclerotiorum system has presented significant challenges in researching rapeseed defense strategies. Here, we focus on the infection process of S. sclerotiorum, the defense mechanisms of rapeseed, and recent research progress in this system. The response of rapeseed to S. sclerotiorum is multifaceted; this review aims to provide a theoretical basis for rapeseed defense strategies.

Nickel potentiates soybean resistance against Sclerotinia sclerotiorum infection

Nickel potentiates soybean resistance against Sclerotinia sclerotiorum infection

Nano-Silicon Triggers Rapid Transcriptomic Reprogramming and Biochemical Defenses in Brassica napus Challenged with Sclerotinia sclerotiorum.

Stem rot caused by Sclerotinia sclerotiorum poses a significant threat to global agriculture, leading to substantial economic losses. To explore innovative integrated pest management strategies and elucidate the underlying mechanisms, this study examined the impact of nano-silicon on enhancing resistance to Sclerotinia sclerotiorum in Brassica napus. Bacteriostatic assays revealed that nano-silicon effectively inhibited the mycelial growth of Sclerotinia sclerotiorum in a dose-dependent manner. Field trials corroborated the utility of nano-silicon as a fertilizer, substantially bolstering resistance in the Brassica napus cultivar Xiangyou 420. Specifically, the disease index was reduced by 39-52% across three distinct geographical locations when compared to untreated controls. This heightened resistance was attributed to nano-silicon's role in promoting the accumulation of essential elements such as silicon (Si), potassium (K), and calcium (Ca), while concurrently reducing sodium (Na) absorption. Furthermore, nano-silicon was found to elevate the levels of soluble sugars and lignin, while reducing cellulose content in both leaves and stems. It also enhanced the activity levels of antioxidant enzymes. Transcriptomic analysis revealed 22,546 differentially expressed genes in Si-treated Brassica napus post-Sclerotinia inoculation, with the most pronounced transcriptional changes observed one day post-inoculation. Weighted gene co-expression network analysis identified a module comprising 45 hub genes that are implicated in signaling, transcriptional regulation, metabolism, and defense mechanisms. In summary, nano-silicon confers resistance to Brassica napus against Sclerotinia sclerotiorum by modulating biochemical defenses, enhancing antioxidative activities, and rapidly reprogramming key resistance-associated genes. These findings contribute to our mechanistic understanding of Si-mediated resistance against necrotrophic fungi and offer valuable insights for the development of stem-rot-resistant Brassica napus cultivars.

Potential for Cultural Management of Lettuce Drop (Sclerotinia sclerotiorum) in High Tunnels Through Modification of Soil Moisture, Planting Date, and Cultivar

Lettuce is a high-value crop commonly grown in high tunnels. However, lettuce drop, caused by Sclerotinia sclerotiorum, can greatly impact lettuce production and profitability. Crop loss from S. sclerotiorum can be especially severe in high tunnels because of intensive cropping and limited options for non-host rotations. A study was conducted in a Kentucky high tunnel infested with S. sclerotiorum to determine if soil moisture, planting date, and host resistance can successfully manage lettuce drop. The experiment was arranged in a split-split plot design with soil moisture (high: 60 to 100%, low: 40 to 80% plant available water), planting date (early, mid, and late spring), and lettuce cultivar (Galactic, Harmony, Pirat, and Vulcan) being the main plot, subplot, and sub-subplot factors, respectively. In year one, lettuce drop incidence was significantly lower in the low soil moisture and early planting date, and significantly higher in Pirat lettuce. Marketable lettuce weight was significantly higher in the late planting and Vulcan treatments. In year two, lettuce drop incidence was significantly lower in the late planting and Galactic compared with all other treatments. There was no significant difference in lettuce drop incidence between the high and low soil moisture in year two. Harmony and Vulcan had significantly higher marketable weight compared with all cultivars. Planting date and lettuce cultivar had the strongest effect on lettuce drop incidence. Although mid-spring is considered the ideal time to plant lettuce in Kentucky, growers managing lettuce drop should consider planting earlier or later and selecting resistant cultivars appropriate for their markets.

Discovery of Novel Pyrazol-5-yl-benzamide Derivatives Containing a Thiocyanato Group as Broad-Spectrum Fungicidal Candidates.

In an effort to promote the development of new fungicides, a series of 48 novel N-(1-methyl-4-thiocyanato-1H-pyrazol-5-yl)-benzamide derivatives A1-A36 and B1-B12 were designed and synthesized by incorporating a thiocyanato group into the pyrazole ring, and their fungicidal activities were evaluated against Sclerotinia sclerotiorum, Valsa mali, Botrytis cinerea, Rhizoctonia solani, and Phytophthora capsici. In the in vitro antifungal/antioomycete assay, many of the target compounds exhibited good broad-spectrum fungicidal activities. Among them, compound A36 displayed the best antifungal activity against V. mali with an EC50 value of 0.37 mg/L, which was significantly higher than that of the positive controls fluxapyroxad (13.3 mg/L) and dimethomorph (10.3 mg/L). Meanwhile, compound B6 exhibited the best antioomycete activity against P. capsici with an EC50 value of 0.41 mg/L, which was higher than that of azoxystrobin (29.2 mg/L) but lower than that of dimethomorph (0.13 mg/L). Notably, compound A27 displayed broad-spectrum inhibitory activities against V. mali, B. cinerea, R. solani, S. sclerotiorum, and P. capsici with respective EC50 values of 0.71, 1.44, 1.78, 0.87, and 1.61 mg/L. The in vivo experiments revealed that compounds A27 and B6 presented excellent protective and curative efficacies against P. capsici, similar to that of the positive control dimethomorph. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses showed that compound B6 could change the mycelial morphology and severely damage the ultrastructure of P. capsici. The results of the in vitro SDH enzymatic inhibition experiments indicated that compounds A27 and B6 could effectively inhibit the activity of P. capsici SDH (PcSDH). Furthermore, molecular docking analysis demonstrated significant hydrogen bonds and Pi-S bonding between the target compounds and the key amino acid residues of PcSDH, which could explain the probable mechanism of action. Collectively, these studies provide a valuable approach to expanding the fungicidal spectrum of pyrazol-5-yl-benzamide derivatives.

Isolation and Identification of Air Microflora in Clifford University Medical Center, Ihie Campus, Owerrinta, Abia State, Nigeria

The settling plate method was used to examine the air microflora in 6 units at the Clifford University Medical Centre, Ihie campus, Owerrinta, Abia state, Nigeria. The male ward, male restroom, female ward, female restroom, theater room, and environment were among the 6 units. At each of the sample locations, the culture plates containing potato dextrose agar and nutrient agar media were exposed to the atmosphere for about 15 minutes. A total count of 11 CFU and 295 CFU fungal and bacterial isolates respectively were identified from the medical center but 5 fungal isolates and 29 bacterial isolates were obtained as pure cultures. These fungi were Aspergillus flavus, Aspergillus niger, Trichophyton sp, Penicillium sp, and white mold. The bacterial genera were Staphylococcus sp, Streptococcus sp, Micrococcus sp, and Bacillus sp. Staphylococcus sp and Aspergillus sp. were the two most prevalent microorganisms in this investigation. It can be said that the Clifford University Medical Centre employed for this study featured numerous types of Gram-positive bacteria, a high prevalence of pathogenic bacteria, and a high prevalence of pathogenic fungi in both the indoor and outdoor air. The majority of the fungal isolates are molds, whereas certain bacterial species are commensals that live on human skin, the fungal isolates are of environmental origin. The bacterial and fungal isolates contained a few non-pathogenic species. The study was carried out to determine if air microfloral affects the infection rate in the University Medical Centre.

Plant Growth-Promoting Endophytic Bacteria Isolated from Miscanthus giganteus and Their Antifungal Activity.

Modern technologies can satisfy human needs only with the use of large quantities of fertilizers and pesticides that are harmful to the environment. For this reason, it is possible to develop new technologies for sustainable agriculture. The process could be carried out by using endophytic microorganisms with a (possible) positive effect on plant vitality. Bacterial endophytes have been reported as plant growth promoters in several kinds of plants under normal and stressful conditions. In this study, isolates of bacterial endophytes from the roots and leaves of Miscanthus giganteus plants were tested for the presence of plant growth-promoting properties and their ability to inhibit pathogens of fungal origin. Selected bacterial isolates were able to solubilize inorganic phosphorus, fix nitrogen, and produce phytohormones, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, and siderophore. Leaf bacterial isolate Pantoea ananat is 50 OL 2 had high production of siderophores (zone ≥ 5 mm), and limited phytohormone production, and was the only one to show ACC deaminase activity. The root bacterial isolate of Pseudomonas libanensis 5 OK 7A showed the best results in phytohormone production (N6-(Δ2-isopentenyl)adenine and indole-3-acetic acid, 11.7 and 12.6 ng·mL-1, respectively). Four fungal cultures-Fusarium sporotrichioides DBM 4330, Sclerotinia sclerotiorum SS-1, Botrytis cinerea DS 90 and Sphaerodes fimicola DS 93-were used to test the antifungal activity of selected bacterial isolates. These fungal cultures represent pathogenic families, especially for crops. All selected root endophyte isolates inhibited the pathogenic growth of all tested fungi with inhibition percentages ranging from 30 to 60%. Antifungal activity was also tested in two forms of immobilization of selected bacterial isolates: one in agar and the other on dextrin-coated cellulose carriers. These results demonstrated that the endophytic Pseudomonas sp. could be used as biofertilizers for crops.

Bacillus mexicanus sp. nov., a biological control bacterium isolated from the common bean (Phaseolus vulgaris L.) crop in Sinaloa, Mexico.

Strain FSQ1T was isolated from the rhizosphere of the common bean (Phaseolus vulgaris L.) crop sampled in a commercial field located in the Gabriel Leyva Solano community, which belongs to the Guasave municipality (state of Sinaloa, Mexico). Based on its full-length 16S rRNA gene sequence, strain FSQ1T was assigned to the genus Bacillus (100 % similarity). This taxonomic affiliation was supported by its morphological and metabolic traits. Strain FSQ1T was a Gram-stain-positive bacterium with the following characteristics: rod-shaped cells, strictly aerobic, spore forming, catalase positive, reduced nitrate to nitrite, hydrolysed starch and casein, grew in the presence of lysozyme and 2 % NaCl, utilized citrate, grew at pH 6.0-8.0, produced acid from glucose, was unable to produce indoles from tryptophan, and presented biological control against Sclerotinia sclerotiorum. The whole-genome phylogenetic results showed that strain FSQ1T formed an individual clade in comparison with highly related Bacillus species. In addition, the maximum values for average nucleotide identity and from Genome-to-Genome Distance Calculator analysis were 91.57 and 44.20 %, respectively, with Bacillus spizizenii TU-B-10T. Analysis of its fatty acid content showed the ability of strain FSQ1T to produce fatty acids that are not present in closely related Bacillus species, such as C18 : 0 and C20 : 0. Thus, these results provide strong evidence that strain FSQ1T represents a novel species of the genus Bacillus, for which the name Bacillus mexicanus sp. nov. is proposed. The type strain is FSQ1T (CM-CNRG TB51T=LBPCV FSQ1T).

Unveiling the molecular basis of Stem-Physical-Strength-Mediated-Resistance (SPSMR) mechanism against Sclerotinia sclerotiorum in oilseed Brassica: A comparative transcriptome analysis between resistant Sinapis alba and susceptible Brassica juncea

This study elucidates the intricate molecular dynamics of the Stem-Physical-Strength-Mediated-Resistance (SPSMR) mechanism against Sclerotinia sclerotiorum in oilseed Brassica. This study explores how resistant and susceptible genotypes respond to S. sclerotiorum and their stem physical strength at various infection stages, revealing the molecular basis of SPSMR-mechanism. Statistically significant differences (P ≤ 0.05) were observed between genotypes over time, where the resistant genotype showed reduced stem lesion length, stem diameter, and stem water content, along with increased stem dry matter content, stem specific density, stem breaking force, stem breaking strength, and lignin content compared to the susceptible counterpart. Through gene expression analysis, the study unraveled unique patterns of differentially expressed genes linked to cell wall reinforcement, pathogenesis and disease resistance. Upregulation of genes associated with arabinogalactan protein, xyloglucan endotransglucosylase/hydrolase, pectinesterase, expansins, S-adenosylmethionine-dependent methyltransferase, wall-associated kinases, peroxidases, laccases and phenylalanine ammonia-lyase as well as other genes associated with lignin-biosynthesis was evident in the resistant genotype. Additionally, gene ontology and KEGG enrichment analyses highlights the synergy between stem physical strength and molecular components, revealing a distinctive defense strategy involving the coordinated upregulation of genes responsible for cell-wall strengthening, disease resistance, and pathogenesis-related proteins in the resistant genotype. Conversely, compromised expression patterns in the susceptible genotype underscore its challenge in mounting a robust defense. Strikingly, genes regulating intracellular pH homeostasis emerge as potential countermeasures against S. sclerotiorum virulence. Ultimately, these findings provide a new perspective on the molecular basis of the SPSMR mechanism in boosting host genetic resistance against S. sclerotiorum in oilseed Brassica and other hosts. However, future research is required to investigate diverse genotypes, additional pathways, and regulatory elements in order to achieve a comprehensive understanding of SPSMR in oilseed Brassica.

Chalcone derivatives containing thiazole fragment: Synthesis and antifungal activity

28 chalcone derivatives containing thiazole fragment were synthesized. The results of antifungal bioactivity tests suggested that most of the compounds possessed superior in vitro antifungal activities against nine plant pathogenic fungi. T17 showed excellent bioactivity against Sclerotinia sclerotiorum (S. sclerotiorum) with an EC50 value of 12.9 μg/mL, which was better than that of azoxystrobin (15.1 μg/mL). Further than that, T11 exhibited good bioactivity against Phytophthora capsici (P. capsici) with an EC50 value of 15.8 μg/mL, which was superior to that of azoxystrobin (40.2 μg/mL). The bioactivity test was carried out in oilseed rape in vivo. The protective and curative activities of T17 on oilseed rape infected with S. sclerotiorum were 86.5 and 75.2 %, respectively, which were higher than those of azoxystrobin (71.4 and 68.6 %) at 200 μg/mL. Scanning electron microscopy results indicated that the mycelium collapsed and folded after T17 treatment, which changed the mycelial morphology, inhibiting the growth of mycelium, thus achieving an inhibitory effect on S. sclerotiorum. In addition, the mechanism of action studies manifested that the results were further verified by performing in vivo antifungal activity assay, fluorescence microscopy, light microscopy, cell membrane permeability, leakage of cellular contents, and malondialdehyde content assay. This study demonstrates that compound T17 has the potential to become a novel fungicide.

XLG2 and CORI3 function additively to regulate plant defense against the necrotrophic pathogen Sclerotinia sclerotiorum.

The membrane-bound heterotrimeric G-proteins in plants play a crucial role in defending against a broad range of pathogens. This study emphasizes the significance of Extra-large Gα protein 2 (XLG2), a plant-specific G-protein, in mediating the plant response to Sclerotinia sclerotiorum, which infects over 600 plant species worldwide. Our analysis of Arabidopsis G-protein mutants showed that loss of XLG2 function increased susceptibility to S. sclerotiorum, accompanied by compromised accumulation of jasmonic acid (JA) during pathogen infection. Overexpression of the XLG2 gene in xlg2 mutant plants resulted in higher resistance and increased JA accumulation during S. sclerotiorum infection. Co-immunoprecipitation (co-IP) analysis on S. sclerotiorum infected Col-0 samples, using two different approaches, identified 201 XLG2-interacting proteins. The identified JA-biosynthetic and JA-responsive proteins had compromised transcript expression in the xlg2 mutant during pathogen infection. XLG2 was found to interact physically with a JA-responsive protein, Coronatine induced 1 (CORI3) in Co-IP, and confirmed using split firefly luciferase complementation and bimolecular fluorescent complementation assays. Additionally, genetic analysis revealed an additive effect of XLG2 and CORI3 on resistance against S. sclerotiorum, JA accumulation, and expression of the defense marker genes. Overall, our study reveals two independent pathways involving XLG2 and CORI3 in contributing resistance against S. sclerotiorum.

Mechanisms of Primed Defense: Plant Immunity Induced by Endophytic Colonization of a Mycovirus-Induced Hypovirulent Fungal Pathogen.

How mycovirus-induced hypovirulence in fungi activates plant defense is still poorly understood. The changes in plant fitness and gene expression caused by the inoculation of the fungus Sclerotinia sclerotiorum harboring and made hypovirulent by the mycovirus soybean leaf-associated gemygorvirus-1 (SlaGemV-1) of the species Gemycircularvirus soybe1 were examined in this study. As the hypovirulent fungus (DK3V) colonized soybean Glycine max, plant transcriptomic analysis indicated changes in defense responses and photosynthetic activity, supported by an upregulation of individual genes and overrepresentation of photosystem gene ontology groups. The upregulated genes include genes relating to both pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity as well as various genes relating to the induction of systemic acquired resistance and the biosynthesis of jasmonic acid. Plants colonized with DK3V showed a resistant phenotype to virulent S. sclerotiorum infection. Plant height and leaf area were also determined to be larger in plants grown with the virus-infected fungus. Here, we hypothesize that inoculation of soybean with DK3V can result in the triggering of a wide range of defense mechanisms to prime against later infection. The knowledge gained from this study about plant transcriptomics and phenotype will help prime plant immunity with mycovirus-infected hypovirulent fungal strains more effectively. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

First report of Sclerotinia sclerotiorum causing Sclerotinia wilt of hop (Humulus lupulus) in Poland.

The common hop (Humulus lupulus L., Cannabaceae) is a perennial plant cultivated in the temperate climate zone and used in the brewing and pharmaceutical industry. In June 2021, symptoms of wilting and subsequent drying of shoots were observed on hop plants (cv. Lubelski) in Lubelskie Province, in Poland (50°55'30.5"N, 22°10'35.4"E). Wilted shoots showed no symptoms of chlorosis. Usually both healthy and wilted shoots were present on the same plant. Approx. 20% of the plants in the 2 hectare hop garden showed these symptoms. An inspection of the underground parts of the infected shoots revealed a brown necrosis of the tissues partly covered by white mycelium with black sclerotia. These symptoms were characteristic for Sclerotinia sclerotiorum (Lib.) de Bary (Bolton et al. 2006), but this pathogen has never been detected in hop gardens in Poland before. In order to confirm the preliminary diagnosis, shoots from five different plants with symptoms of necrosis were collected, disinfected with 1% sodium hypochlorite for 1 min, rinsed with sterile water and dried. Twelve fragments from partially necrotized tissue were placed on potato dextrose agar (PDA) amended with chlortetracycline hydrochloride. After three days of incubation at room temperature and daylight, 75% of the explants had white or light grey mycelia present. Pure cultures were obtained by transplanting mycelium to fresh PDA. Within 4 days, the mycelium has reached the diameter of Petri dishes (90 mm). On PDA at room temperature and daylight, black spherical or cylindrical sclerotia formed after 6-14 days. Sclerotial size was 1.0 to 10.0 x 1.0 to 5.0 mm (average 2.8 x 2.0 mm; n = 57 from 3 plates). Five isolates were subjected to DNA extraction. Then ITS region was amplified and sequenced using primers ITS1/ITS4 (White et al. 1990). The sequences obtained from the five fungal isolates were identical with each other and BLAST analysis revealed also 100% identity with the GenBank records of S. sclerotiorum (e.g. KT224645, Baturo-Ciesniewska et al. 2017). One representative sequence of isolate Ss5HL was deposited to GenBank (OQ998981). Pathogenicity of the isolate Ss5HL was confirmed in inoculation tests on approx. 30 cm high, young shoots of hop plants (cv. Lubelski) grown from rootstock for 4 weeks in the greenhouse. Five plants were inoculated by placing mycelial discs from a 7-day-old culture on shoots and covering them with wet sterilized cotton pads and aluminum foil. Two control plants were treated in the same way but instead of mycelial discs pure agar discs were placed on the shoots. Then plants were kept in a climate chamber (80% relative humidity, 15-h light at 22°C, 9-h dark at 18°C). All fungal inoculated shoots wilted within 3-4 days, then necrosis developed and spread from the place of inoculation up the shoot. No tissue necrosis was observed below the place of inoculation. The control plants remained asymptomatic. The inoculation test was carried out twice with the same result. Fungal cultures reisolated from the inoculated shoots were morphologically identical with the culture used as inoculum. Isolate Ss5HL was deposited in the collection of the Westerdijk Fungal Biodiversity Institute (CBS 150077).To our knowledge, this is the first case of Sclerotinia wilt of hops in Poland and also in Europe, with the exception of one, nearly 100 years old report from the United Kingdom (Salmon and Ware 1936). S. sclerotiorum rarely occurs on hop but it can cause severe yield reduction if pathogen accumulates in the soil.

The influence of biostimulants on the rhizospheric microorganisms of scorzonera (Scorzonera hispanica L.)

Scorzonera (Scorzonera hispanica L.) is a particularly valuable species among little-known and rarely cultivated vegetables. It is a root vegetable of high dietary and nutritional values. The suitable microbiological activity of the soil favors the growth and development of scorzonera. Biostimulants can positively affect the communities of rhizospheric microorganisms of cultivated plants, including this important vegetable. The studies established the influence of biostimulants on the microbial communities in the scorzonera rhizosphere. Before setting up the field experiment, scorzonera seeds were dressed with fungicide Zaprawa Nasienna T 75 DS/WS or biostimulants Beta-Chikol, Bio-Algeen S-90, and Asahi SL. The laboratory microbiological analyses of scorzonera rhizosphere soil were conducted and determined the total population of bacteria and fungi. The obtained rhizosphere isolates of fungi Albifimbria, Clonostachys, Epicoccum, Penicillium, and Trichoderma sp. were tested to check the influence on fungi pathogenic to scorzonera (Fusarium culmorum, Fusarium oxysporum, Sclerotinia sclerotiorum, and Rhizoctonia solani). The experiments showed that biostimulants, especially Asahi SL and Beta-Chikol, favored the development of rhizobacteria populations (including Bacillus sp. and Pseudomonas sp.). All biostimulants (Beta-Chikol, in particular) and the fungicide decreased the population of rhizospheric fungi and limited the occurrence of polyphagous fungi in the rhizosphere of scorzonera. Biostimulant Beta-Chikol and fungicide Zaprawa Nasienna T 75 DS/WS were most effective in stimulating the development of antagonistic fungi. Clonostachys rosea, Trichoderma sp., and Albifimbria verrucaria predominated as antagonistic rhizospheric fungi.

RALF22 promotes plant immunity and amplifies the Pep3 immune signal.

Rapid alkalinization factors (RALFs) in plantshave been reported to dampen pathogen-associated molecular pattern (PAMP)-triggered immunity via suppressing PAMP-induced complex formation between the pattern recognition receptor (PRR) and its co-receptor BAK1. However, the direct and positive role of RALFs in plant immunity remains largely unknown. Herein, we report the direct and positive roles of a typical RALF, RALF22, in plant immunity. RALF22 alone directly elicited a variety of typical immune responses and triggered resistance against the devastating necrotrophic fungal pathogen Sclerotinia sclerotiorum in a FERONIA (FER)-dependent manner. LORELEI (LRE)-like glycosylphosphatidylinositol (GPI)-anchored protein 1 (LLG1) and NADPH oxidase RBOHD were required for RALF22-elicited reactive oxygen species (ROS) generation. Themutation of cysteines conserved in the C terminus of RALFs abolished, while the constitutive formation of two disulfide bridges between these cysteines promoted the RALF22-elicited ROS production and resistance against S. sclerotiorum, demonstrating the requirement of these cysteines in the functions of RALF22 in plant immunity. Furthermore, RALF22 amplified the Pep3-induced immune signal by dramatically increasing the abundance of PROPEP3 transcript and protein. Supply with RALF22 induced resistance against S. sclerotiorum in Brassica crop plants. Collectively, our results reveal that RALF22 triggers immune responses and augments the Pep3-induced immune signal in a FER-dependent manner, and exhibits the potential to be exploited as an immune elicitor in crop protection.

Сравнително изпитване устойчивостта на образци фасул към склеротинийно гниене (Sclerotinia sclerotiorum) чрез директен и индиректен метод

White mold, caused by Sclerotinia sclerotiorum, is a key disease of common beans in temperate and subtropical climates. For the climatic conditions of Bulgaria, the infection occurs mainly as a result of mycelogenic development of the sclerotia, which is why the disease is observed mostly in varieties with a prostrate type of the habitus. Due to the wide range of hosts of the pathogen and long-term preservation of sclerotia in the soil, agrotechnical measures have little effect in controlling the fungus. Therefore, breeding resistant varieties are the most effective measure to prevent the disease. The selection of appropriate and verified methods for testing the source and breeding materials is of primary importance for the success of breeding programs to increase resistance to the pathogen. The present study aimed to compare the response of bean accessions to S. sclerotiorum, by applying a direct and indirect evaluation method with a view to their parallel use in the breeding process. The studies were conducted under greenhouse conditions, and 29 bean accessions were included in them. The accessions were grown in pots (45x30x10 cm) with a soil-sand mixture. In the first trifoliate leaf, the stem was cut at 3 cm from the node of the primary leaves (STAW test). A single-sided closed plastic straw containing an agar disc from the periphery of 3-day-old cultures of four isolates cultivated on PDA medium (five plants per isolate), was placed on the cut. The reaction of the accessions was recorded 7 days after inoculation on a 9-point scale. The cut plant parts (stem and trifoliate leaf) were immersed in oxalic acid solution (20 mM brought to pH=4.0 with 1N NaOH), five plants per sample. The cut plant parts immersed in sterile water adjusted to pH=4.0 with 1N HCl were used for the control. The reaction of the accessions was recorded after 19h on a 9-point scale. The data were processed with the SPSS stat. ver. 19 software. Significant differences were observed in the response of the accessions concerning the isolates used. Weak positive or negative correlations were found between the oxalate test and the STRAW test, and the direction was related to the aggressiveness of the isolates. It was established that for accessions A195, ‘GTB Scythia’, ‘Izabel’, ‘Rhodopeia’ and ‘Pirina’ the results of the oxalic test are comparable to those of the STRW-test. The obtained results give us reason to recommend the application of the oxalate test in the initial generations of the breeding materials, after a preliminary comparative analysis of the parental forms by both methods.

The Complete Genome Sequence of Sclerotinia sclerotiorum (S1), One of the Pathogens Causing Sclerotinosis in Mulberry Fruit

Sclerotinia sclerotiorum is a fungal pathogen that infects an extremely wide range of hosts and can cause diseases in over 600 plant species. In this study, Sclerotinia sclerotiorum (strain S1), which causes sclerotinosis in mulberry fruits, was isolated from the mulberry orchard at the Chongqing Academy of Agricultural Sciences, China, and its complete genome was sequenced using PacBio Sequel II. The assembly consists of 24 contigs with an estimated genome size of 38.91 Mbp and is predicted to encode 9,920 protein-coding genes. This is the first genomic information for Sclerotinia sclerotiorum isolated from diseased mulberry fruit and represents a valuable resource for a comprehensive understanding of Sclerotinia spp. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .