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Fungi (Neolentinus lepideus, Nl, and Trametes versicolor, Tv) impart wood rot, leading to economic and environmental issues. To overcome this issue, toxic chemicals are commonly employed for wood preservation, impacting the environment and human health. Surface coatings based on antimicrobial chitosan (CS) of high molar mass (145 × 105 Da) were tested as wood preservation agents using an innovative strategy involving ultra-pressurizing CS solutions to deposit organic coatings on wood samples. Before coating deposition, the antifungal activity of CS in diluted acetic acid (AcOOH) solutions was evaluated against the rot fungi models Neolentinus lepideus (Nl) and Trametes versicolor (Tv). CS effectively inhibited fungal growth, particularly in solutions with concentrations equal to or higher than 0.125 mg/mL. Wood samples (Eucalyptus sp. and Pinus sp.) were then coated with CS under ultra-pressurization at 70 bar. The polymeric coating deposition on wood was confirmed through X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) images, and water contact angle measurements. Infrared spectroscopy (FTIR) spectra of the uncoated and coated samples suggested that CS does not penetrate the bulk of the wood samples due to its high molar mass but penetrates in the surface pores, leading to its impregnation in wood samples. Coated and uncoated wood samples were exposed to fungi (Tv and Nl) for 12 weeks. In vivo testing revealed that Tv and Nl fungi did not grow on wood samples coated with CS, whereas the fungi proliferated on uncoated samples. CS of high molar mass has film-forming properties, leading to a thin hydrophobic film on the wood surface (water contact angle of 118°). This effect is mainly attributed to the high molar mass of CS and the hydrogen bonding interactions established between CS chains and cellulose. This hydrophobic film prevents water interaction, resulting in a stable coating with insignificant leaching of CS after the stability test. The CS coating can offer a sustainable strategy to prevent wood degradation, overcoming the disadvantages of toxic chemicals often used as wood preservative agents. [ABSTRACT FROM AUTHOR]

We conducted a five‐year survey (2011–2015) of barley and wheat fields in Paraná state, Brazil, obtaining 754 Fusarium isolates from spikes with fusarium head blight (FHB)‐symptoms. Multilocus genotyping and TEF‐1α gene sequence analyses confirmed the dominance of the F. graminearum species complex (FGSC, 75.7%), but F. poae (11.5%), as well as F. avenaceum and related members of the F. tricinctum species complex (FTSC, 8.1%) appeared as substantial contributors to FHB. Within the FGSC, F. graminearum of the 15‐ADON genotype was dominant (63%), followed by F. meridionale of the NIV genotype (23.1%), F. cortaderiae of the NIV (7%) or 3‐ADON (2.6%) genotypes, and F. austroamericanum (3.8%) of the 3‐ADON genotype. Substantial variation in pathogen composition was observed across years, with F. poae and F. meridionale frequencies significantly elevated in some years. Most F. poae strains produced DAS, diANIV, and butenolide, but not neosolaniol, T‐2, or HT‐2. All FTSC species produced moniliformin. Enniatin production was widespread among FTSC species, with the single F. acuminatum strain found to be the strongest producer of enniatins. Our findings confirm FGSC as a major contributor to FHB and expand considerably our knowledge of the presence, frequency, and conditions under which other pathogens may emerge, altering the spectrum of toxins that may accumulate in grain. [ABSTRACT FROM AUTHOR]

Fusarium graminearum is ranked among the five most destructive fungal pathogens that affect agroecosystems. It causes floral diseases in small grain cereals including wheat, barley, and oats, as well as maize and rice. We conducted a systematic review of peer-reviewed studies reporting species within the F. graminearum species complex (FGSC) and created two main data tables. The first contained summarized data from the articles including bibliographic, geographic, methodological (ID methods), host of origin and species, while the second data table contains information about the described strains such as publication, isolate code(s), host/substrate, year of isolation, geographical coordinates, species and trichothecene genotype. Analyses of the bibliographic data obtained from 123 publications from 2000 to 2021 by 498 unique authors and published in 40 journals are summarized. We describe the frequency of species and chemotypes for 16,274 strains for which geographical information was available, either provided as raw data or extracted from the publications, and sampled across six continents and 32 countries. The database and interactive interface are publicly available, allowing for searches, summarization, and mapping of strains according to several criteria including article, country, host, species and trichothecene genotype. The database will be updated as new articles are published and should be useful for guiding future surveys and exploring factors associated with species distribution such as climate and land use. Authors are encouraged to submit data at the strain level to the database, which is accessible at https://fgsc.netlify.app. [ABSTRACT FROM AUTHOR]

Pyrenophora teres f. teres is well known for causing net form net blotch on barley, but its pathogenicity on wheat has also been reported in Hungary (Tóth et al. 2008) and east Russia (Mikhailova et al. 2010). The report from Hungary mentioned symptoms of dark brown necrotic lesions with or without chlorotic margins, while the report from Russia described symptoms similar to tan spot. A survey of fungal pathogens causing leaf spot diseases on wheat in the humid subtropical areas of Paraná State, southern Brazil, was conducted in 2016. Twenty four isolates, representing different wheat fields in the municipalities of Guarapuava and Pinhão, in the state of Paraná, were collected from wheat plants at the soft dough stage. The isolates analyzed in our study were obtained from leaf fragments of wheat cv. Toruk and were removed from the edge of lesions resembling tan spot, a major fungal disease of wheat in that region, caused by Pyrenophora tritici-repentis . The leaves presented oval, diamond, or elongate-shape lesions with tan necrotic spots. Still, they did not always show the brown center, which seemed not very characteristics of tan spot caused by P. tritici-repentis . Yellow halos surrounded the necrotic lesions. The fragments were superficially disinfected for 30 sec in 0.5% sodium hypochlorite, washed in sterile water, dried with a sterile paper towel, and transferred to petri plates containing potato dextrose agar (PDA) medium. After four days of incubation at 24±2ºC and a photoperiod of 12 h, hyphal tips were removed from the PDA medium and transferred to petri plates containing V-8 medium. Plates were incubated for 14 days in alternate cycles of 12 h at 23±2ºC under light and 12 h at 19±2ºC in darkness for sporulation. Pure cultures were obtained from single conidia produced on V-8 medium. Single spore isolates, representing different fields, were obtained from individual leaves. Conidia measuring 38-82 µm × 16-20 µm were smoothly cylindrical and straight, with rounded ends, subhyaline or yellowish brown, with four to seven pseudosepta. Genomic DNA extracted from cultures grown in yeast extract broth medium was used for PCR amplification of the ribosomal internal transcribed spacers and the 5.8S ribosomal DNA gene (ITS-5.8S rDNA) using the primers ITS4 and ITS5 described by White et al. (1990). A BLAST search of the GenBank database revealed that the ITS-5.8S rDNA sequence fragments (505 bp) from 12 out of 67 isolates were 99-100% similar to P. teres accession number EF452452 (Andrie et al. 2008). The DNA sequences of three P. teres isolates (20C3, 20A3, and 20A1) were deposited in GenBank (accession nos. MH594043.1, MH594042.1, and MH594041.1, respectively). These isolates were obtained from different fields in the municipality of Pinhão (25° 42 '26 "S; 51° 38' 0" W), in Paraná State. To test the pathogenicity of the isolates 20C3, 20A3, and 20A1, a conidial suspension for each isolate with 2-3 × 103 conidia per mL was sprayed at the boot stage (BBCH-scale 45) on leaves of wheat cv. Toruk and on susceptible barley cv. Ana 01 plants growing in pots. Each pot containing 5-7 plants was considered as replicate. Wheat plants were also inoculated with a P. tritici-repentis isolate with a conidial suspension at the same concentration described above to serve as reference of symptoms for tan spot. Wheat and barley plants were also inoculated with sterile water to serve as a control. Six replications were inoculated for each treatment. After inoculation, the plants were maintained in a dew chamber for 24 h and then moved to a growth room at 20±2ºC and 16 h photoperiod. Initially, the leaves of wheat plants inoculated with P. teres exhibited small, irregular, dark lesions surrounded by yellow halos, and later exhibited oval to elongate, pale brown, necrotic lesions, and yellow halos. Differently from tan spot caused by P. tritici-repentis , the wheat leaves inoculated with P. teres f. teres presented a more diffuse yellowing, and the center of necrotic lesions was pale brown. The symptoms observed in the barley leaves were the net form net blotch, which allowed us to infer that the disease was caused by P. teres f. teres isolates. All inoculated plants presented symptoms, with some variation among them. Pyrenophora teres f. teres was reisolated from the inoculated wheat and barley plants. This is the first report of P. teres f. teres causing leaf disease on wheat in Brazil. The finding contributes to a better understanding of the etiology of wheat leaf spots in humid subtropical areas of southern Brazil.