Alternaria Tenuissima Research Articles

Isolation and identification of flavonoid-producing endophytic fungi from Loranthus tanakae Franch. & Sav that exhibit antioxidant and antibacterial activities.

Loranthus tanakae Franch. & Sav is a medicinal plant that has a variety of pharmacological properties. However, its study is currently limited because of its relative shortage of natural abundance. The objective of this work was to find an alternative resource from this plant that could produce its bioactive ingredients. We isolated endophytic fungi from the twigs of Loranthus tanakae Franch. & Sav and eight flavonoid-producing endophytic fungi were selected. The eight endophytic fungi meeting the criteria were identified as Alternaria tenuissima, Dothiorella gregaria, Penicillium aethiopicum, Nothophoma quercina and Hypoxylon perforatum by morphological and molecular methods. The antioxidant and antibacterial activities of the flavonoid-producing endophytic fungi were investigated in vitro, where Alternaria tenuissima ZP28 and ZM148 demonstrated greater activities than the other six strains. Flavonoids of ZP28 and ZM148 were preliminarily identified by liquid chromatography-mass spectrometry (LC-MS). After screening the flavonoid-producing endophytic fungi, Alternaria tenuissima ZP28 and ZM148 were found to have good antioxidant and antibacterial activities. Overall, this study provided new direction and resources for the acquisition of flavonoids. Endophytic fungi are a promising alternative approach for the large-scale production of flavonoids from Loranthus tanakae Franch. & Sav.

Molecular characterization of Deciphering Fungal Community structure in Zea mays L. and Triticum Aestivum L

Rhizosphere fungi are strongly associated with plant growth and health by providing nutrients and antagonizing pathogens. Commercially, fungus has multipurpose applications in several sectors including beverages, food items and in medicines. Current study aimed to reveal the core fungal community structure of the two leading cereal crops that are Zea mays L. and Triticum aestivum L. The rhizosphere fungal community was explored via morphology, biochemistry and internal transcribe spacer (ITS) metagenomics. On the basis of morphology, the retrieved fungal strains were imprecisely classified into Ascomycota and Zygomycota. The species including Yeast, Botyritis californica, Rhizopus stolonifer, Alternaria tenuissima, Aspergillus terreus, Aspergillus flavus, Aspergillus nidulans, Aspergillus niger and Microsporum canis were identified on the basis of macroscopy and microscope. Moreover, the biochemical characterization depicted the role of fungi in promotion of plant growth. Majority of the isolates depicted catalase activity, indole production, phosphate solubilization, ammonia production, nitrogenase activity and urease activity. Metagenomics using amplicon sequencing of ITS region revealed the presence of 805 Operational Taxonomic Units (OTUs) with 647 OTUs in Zea mays and 620 OTUs in Triticum aestivum. The fungal phyla found in the rhizosphere of Zea mays L. and Triticum aestivum L. were Ascomycota, Basidiomycota, Zygomycota, Chytridiomycota, Incertae sedis fungi. Ascomycota accounted for 93% and 95% of classified fungi in rhizosphere of Zea mays L. and Triticum aestivum L. respectively. The dominant species found in the rhizosphere soil of Zea mays were Gibberella intricans, Curvularia lunata, Lepidosphaeria nicotiae, Edenia gomezpompae and Myrothecium verrucaria.

The Microbiome of the 'Williams' Pear Variety Grown in the Organic Orchard and Antifungal Activity by the Autochthonous Bacterial and Yeast Isolates.

The total diversity of bacterial and fungal communities associated with the phyllosphere (fruits and leaves) of the ‘Williams’ pear variety was analyzed in two phenological stages during fruit development and maturation. The antagonistic potential of autochthonous bacterial and yeast isolates against phytopathogenic fungi was also evaluated. A metabarcoding approach revealed Pantoea, Sphingomonas, Hymenobacter, Massilia, and Pseudomonas as dominant bacterial constituents of the pear phyllosphere, whilst most abundant among the fungal representatives identified were Metschnikowia, Filobasidium, Aureobasidium pullulans, Botrytis cinerea, and Taphrina. The traditional culturable approach revealed that the Pseudomonas genus with P. graminis, P. putida, and P. congelans was most prevalent. The most frequently cultivated fungal representatives belonged to the genus Fusarium with six identified species. A broad range of the antagonistic activity was detected for the Hannaella luteola and Metschnikowia pulcherrima yeasts, significantly affecting the growth of many fungal isolates in the range of 53–70%. Fusarium sporotrichioides was the most susceptible fungal isolate. The autochthonous antagonistic yeasts H. luteola and M. pulcherrima might be powerful biological control agents of postharvest diseases caused by Fusarium spp. and common pathogens like Monilinia laxa, Botrytis cinerea, Alternaria tenuissima, and Cladosporium cladosporioides.

First report of leaf spot caused by Alternaria tenuissima on Salvia caudata in Italy

First report of leaf spot caused by Alternaria tenuissima on Salvia caudata in Italy

Alternaria tenuissima, a biodeteriogenic filamentous fungus from ancient Oplontis ruins, rapidly penetrates tuff stone in an in vitro colonization test

To integrate the understanding of mycological biodeterioration on artistic-historical heritage, we cultivated Alternaria tenuissima on Neapolitan Yellow Tuff (NYT) tiles for 20 d in a low-carbon environment. The fungus, collected within the UNESCO site of ancient Oplontis ruins (Naples, Italy), was monitored during its early colonization both for the epilithic and the cryptoendolithic growth by using photomicrography-based image analyses. The data were integrated with the count of conidia and the analysis of biochemical proxies in order to evaluate the biological status of the fungus during growth. Additionally, we provided novel and synthetic insights on A. tenuissima 3D growth dynamics, suggesting that visible fungal spots on stone monuments could represent the “iceberg tip” for advanced stone decay. Our results confirm that in vitro tests, coupled with microscopical observations and computer image analysis, are useful tools to evaluate and quantify fungal biomass on a stone substratum, especially in the early steps of fungal colonization.

Volatile Organic Compounds and Physiological Parameters as Markers of Potato (Solanum tuberosum L.) Infection with Phytopathogens.

The feasibility of early disease detection in potato seeds storage monitoring of volatile organic compounds (VOCs) and plant physiological markers was evaluated using 10 fungal and bacterial pathogens of potato in laboratory-scale experiments. Data analysis of HS-SPME-GC-MS revealed 130 compounds released from infected potatoes, including sesquiterpenes, dimethyl disulfide, 1,2,4-trimethylbenzene, 2,6,11-trimethyldodecane, benzothiazole, 3-octanol, and 2-butanol, which may have been associated with the activity of Fusarium sambucinum, Alternaria tenuissima and Pectobacterium carotovorum. In turn, acetic acid was detected in all infected samples. The criteria of selection for volatiles for possible use as incipient disease indicators were discussed in terms of potato physiology. The established physiological markers proved to demonstrate a negative effect of phytopathogens infecting seed potatoes not only on the kinetics of stem and root growth and the development of the entire root system, but also on gas exchange, chlorophyll content in leaves, and yield. The negative effect of phytopathogens on plant growth was dependent on the time of planting after infection. The research also showed different usefulness of VOCs and physiological markers as the indicators of the toxic effect of inoculated phytopathogens at different stages of plant development and their individual organs.

Utilization of the antagonistic yeast, Wickerhamomyces anomalus, combined with UV-C to manage postharvest rot of potato tubers caused by Alternaria tenuissima

Postharvest rot of potato tubers caused by fungal pathogens is the main cause of significant economic losses, while also raising potential food safety issues. Integrated disease management, utilizing bio-safe and eco-friendly methods, represents a sustainable strategy for reducing postharvest losses in crops, including potato. In the current study, the application of the antagonistic yeast, Wickerhamomyces anomalus, combined with a UV-C treatment was evaluated for the management of postharvest Alternaria rot of potato tubers, caused by Alternaria tenuissima. Both W. anomalus and UV-C as individual treatments reduced the size of A. tenuissima infections on potato tubers, relative to the control, while the combined treatment of W. anomalus and UV-C exhibited the highest level of inhibition. W. anomalus or UV-C alone, and especially when used in combination, induced the expression of defense-related genes, including polyphenol oxidase, peroxidase, and β-1,3-glucanase, and also increased the level of flavonoids and lignin in potato tubers. Our findings indicate that the mechanism of action by which UV-C enhances the biocontrol effect of W. anomalus against postharvest Alternaria rot includes the activation of defense-related response in potato tubers. The integration of biocontrol agents and physical treatments (e.g., UV-C) represents an effective, eco-friendly hurdle technology for managing postharvest rot in potato.

Illumina-Based Analysis Yields New Insights Into the Fungal Contamination Associated With the Processed Products of Crataegi Fructus.

Crataegi Fructus, a medicinal and edible herb in China, has been considered a popular dietary supplement globally. It is used for the treatment of dyspepsia and chronic heart failure according to the Chinese Pharmacopoeia (2020). However, fungal contamination in Crataegi Fructus affects its quality and safety, thus preventing its global promotion. In this study, we comprehensively studied the fungal community in processed products of Crataegi Fructus by high-throughput sequencing. A total of 21 Crataegi Fructus samples were collected from five provinces in China, and the samples were divided into five groups based on collection areas, as well as into three groups based on processing methods. We then targeted the internal transcribed spacer 2 sequence through the Illumina Miseq PE300 platform to investigate fungal composition and diversity. Results showed that all 21 samples were detected with fungal contamination, and Ascomycota was dominant at the phylum level. In the groups based on collection areas, Dothideomycetes, Pleosporaceae, and Alternaria were dominant at the class, family, and genus levels, respectively. In the groups based on processing methods, Dothideomycetes, Aspergillaceae, and Alternaria were the most abundant at the class, family, and genus levels, respectively. Differences in fungal communities between various groups were also observed. Furthermore, a total of 115 species were identified, among which seven were potential toxigenic, namely, Trichothecium roseum, Alternaria tenuissima, Aspergillus carbonarius, Penicillium brevicompactum, Aspergillus fumigatus, Rhizopus microspores, and Pichia fermentans. In conclusion, this study reveals great fungal richness and diversity of Crataegi Fructus, providing references for the prevention and control of fungal contamination of Crataegi Fructus in practical production.

First Report of Alternaria tenuissima Causing Leaf Black Spot on Pecan in China.

China is one of the largest markets for pecan (Carya illinoinensis) consumption in the world, and also, pecan production in China has been increased by years since 2008 (Zhang et al. 2015). From July to September in the year 2019 and 2020, leaf black spot was observed on several pecan cultivars including Pawnee, Burkett, Kiowa and Western schley in the germplasm in Liuhe county, Nanjing, Jiangsu Province, China. Disease incidence was approximately 40% in 2019 and 50% in 2020 respectively. Small, dark brown to black spots on leaves were observed initially, and spots expanded quickly into circular or irregular when spots coalesced. In severe cases, the disease can obviously weaken the tree vigor, ultimately leading to losses in yield. Disease symptoms were not observed on the fruits. To determine the causal agent of black leaf spot, symptomatic leaves were collected and cut into pieces (approximately 3 × 3 cm2), surface sterilized with 1% sodium hypochlorite for 2 min and 75% ethanol for 30 s and rinsed twice with sterile distilled ddH2O. Dried tissues were placed on potato dextrose agar (PDA) amended with rifampin (Solarbio, Beijing, China) at a final concentration of 100 µg/mL and incubated at 25°C for 7 days in darkness. Five colonies were obtained and purified by single spore culture for morphological characterization. Colonies were initially white, turned to dark olivaceous with white margin and moderate to abundant gray aerial hyphae. Conidiophores were linear, light brown in color and appeared as individuals or in clusters. Conidia were pale brown to brown, typically obclavate or obpyriform (8 - 49 µm× 3 - 18 µm), with one to five transverse septa and zero to three longitudinal septa (n=50). Conidia of all isolates produced no beaks or a short beak. Based on conidial morphological characteristics, isolates were tentatively identified as Alternaria tenuissima (Simmons 2007). To further confirm the five isolates, the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA), partial region of the histone 3 (H3) gene, translation elongation factor 1-α gene (TEF) and the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were amplified with PCR primer sets ITS1/ITS4 (White et al. 1990), H3-1a/H3-1b (Glass and Donaldson 1995), EF1-728F/EF1-986R (Carbone and Kohn 1999), and GDF1/GDR1 (Berbee et al. 1999) respectively. The sequences were deposited in GenBank (ITS, MN822659 to MN822661 and MZ182355 to MZ182356; histone 3, MN840997 to MN840999 and MZ202355 to MZ202356; TEF, MZ246595 to MZ246599; GAPDH, MZ246590 to MZ246594). BLAST analysis of the resulting sequences showed 99% to 100 % nucleotide identical to those of A. tenuissima isolates (KP278184 [ITS]; MH824352 [H3]; MN046379 [TEF]; MK683840 [GAPDH]). Therefore, based on morphological characteristics and DNA sequences data, the five isolates were identified as A. tenuissima. To determine the pathogenicity of the five isolates, 10 µL of 105 conidia /mL suspension from each isolate was placed to three intact young leaves (Pawnee) respectively. Leaves inoculated with ddH2O in the same manner served as the controls. Inoculated leaves were placed in a growth chamber at 28°C with 95% relatively humidity (RH). Black spot symptoms appeared on all inoculated leaves by 7 days post inoculation, A. tenuissima were re-isolated from the inoculated leaves with isolates and reconfirmed by morphological characteristics, thus fulfilling the Koch's postulates. The controls remained symptomless. Pathogenicity tests were conducted twice. To our knowledge, this is the first report of A. tenuissima causing black leaf spot on pecan in China. Although we have not found any fruit infection, we think the disease is also a potential threat to pecan fruits and production. If more reports of this pathogen are found on pecans, then it is necessary to study and develop effective control strategies.

Co-Application of Tetramycin and Chitosan in Controlling Leaf Spot Disease of Kiwifruit and Enhancing Its Resistance, Photosynthesis, Quality and Amino Acids.

Leaf spot disease caused by Lasiodiplodia theobromae and Alternaria tenuissima is a seriously fungal disease in kiwifruit production. In this study, the co-application of tetramycin and chitosan against leaf spot disease in kiwifruit and its effects on the disease resistance, photosynthesis, quality and amino acids of kiwifruit were investigated. The results show that tetramycin exhibited an excellent antifungal activity against L. theobromae and A. tenuissima with EC50 values of 2.37 and 0.16 mg kg−1. In the field, the foliar co-application of tetramycin and chitosan could effectively control leaf spot disease with control efficacy of 89.44% by spraying 0.3% tetramycin aqueous solutions (AS) 5000 time liquid + chitosan 100 time liquid, which was significantly (ANOVA, p < 0.01) higher than 79.80% of 0.3% tetramycin AS 5000 time liquid and 56.61% of chitosan 100 time liquid. Simultaneously, the co-application of tetramycin and chitosan was more effective than tetramycin or chitosan alone in enhancing the disease resistance and photosynthesis of kiwifruit leaves, as well as improving the quality and amino acids of kiwifruit fruits. This work highlights that chitosan is a practicable, cost-effective and eco-friendly adjuvant of tetramycin for controlling leaf spot disease of kiwifruit, enhancing resistance and photosynthesis of leaves and improving quality and amino acids of fruits.

Evaluation of Indoor and Outdoor Fungal Flora of Two Poultry Farms in Akungba-Akoko and Ayegunle-Akoko

Good quality of air in poultry farms is a prerequisite for healthy animals and farm workers. Air acts as a good dispersal medium for microbes and its quality is a reflection of the environment. The focus of this study is was evaluate indoor and outdoor fungal flora of two poultry farms (Akungba-Akoko and Ayegunle-Akoko) and to determine effect of some antifungal agents on all isolates. Identity of each fungus was determined by comparing the morphology and microscopic characteristics of each fungus with those in compendium of soil fungi. Air flora sampling was performed both inside and outside premises of farms, and an open-air method was used. Antifungal activity was performed using two antifungal drugs (ketoconazole and nystatin). A total of twenty-three (23) fungal species were obtained belonging to fourteen (14) genera; Aspergillus, Penicillium, Eurotium, Monascus, Alternaria, Cryptococcus, Curvularia, Chrysonilia, Microsporum, Cunninghamella, Bipolaris, Acremonium, Fusarium and Trichoderma. Genera such as Curvularia, Chrysonilia, Cunninghamella and Cryptococcus were not inhibited by antifungal drugs used across all concentrations, while nystatin inhibited 74% of these fungi using concentration of 5 mg/ml with 25 mm being highest zone of inhibition. Ketoconazole’s highest zones of inhibition were found with Alternaria tenuissima (26 mm), Trichoderma harzianum (25 mm) and Aspergillus acidus (25 mm). The study revealed presence of some toxicogenic fungi in poultry environments. Therefore, this study recommends preventive measures like provision of adequate ventilation system, regular cleaning of poultry farms, use of clean equipment, and use of antifungal drugs such as ketoconazole and nystatin (to be used at low concentration) to inhibit and control infections in poultry farms.

Identification and Pathogenicity of Fungi Associated with Leaf Spot of Muskmelon in Eastern Shandong Province, China.

Leaf spot is a serious disease in the growth and development of muskmelon, which can affect its quality and yield. Over the past years, Malianzhuang Muskmelon Base, the main muskmelon producing area in Shandong Province, China, has been seriously affected by leaf spot. Since 2018, symptomatic leaves were collected from 11 production areas of this base to determine the pathogens of muskmelon foliar diseases. Two-hundred fungal strains were isolated and 10 genera and 17 species were identified based on morphological characteristics and multilocus phylogenetic analysis (ITS, GADPH, RPB2, HIS3, EF-1α, and LSU). The most frequently isolated species from each sampling area was Alternaria tenuissima with 77 strains, followed by A. alternata. Pathogenicity experiments showed that A. alternata, A. tenuissima, Fusarium neocosmosporiellum (formerly Neocosmospora vasinfecta), F. acuminatum, Exserohilum rostratum, Bipolaris sorokiniana, and Stagonosporopsis cucurbitacearum (formerly Didymella bryoniae) could cause symptoms highly similar to those of infected leaves observed under natural conditions in the field. Therefore, these fungal isolates are considered to be the primary pathogens causing muskmelon leaf spot, and A. tenuissima and A. alternata were the most common and virulent pathogens in this study. In addition, this is the first study of F. neocosmosporiellum, F. acuminatum, E. rostratum, and B. sorokiniana as pathogens associated to muskmelon leaf spot in China as well as the world.

Isolation of Fungi From Oil-contaminated Soil from Maysan Province, Southern Iraq

Maysan province is one of the most important oil-producing provinces in Iraq, therefore, soil contamination as a result of extraction and processing of the oil is one of the most important environmental problems for the soil and the living organisms present in it. Twenty-seven of fungal species were isolated and identified from soil contaminated with crude oil. Among them, 24 species (88.8%.) belonged to Ascomycota (anamorphs stages) and three (11.2%) Zygomycota. A total of 235 isolates were recovered from sites of study. Aspergillus showed a high number of species (6) and 78 isolates, followed by Alternaria (4 species, 64 isolates). Aspergillus niger has the highest occurrence and frequency values (42.5% and 21.70% respectively) and 51 isolates, and Alternaria alternate (39.16%, 20% and 47 isolates), followed by Rhizopus oryzae with a frequency and occurrence of 17.5% and 8.93% respectively and 21 isolates, on other hand, 8 species revealed the lowest occurrence and frequency reaching 0.83%, 0.42 respectively. Eight species were isolated described as new records from Iraq, which are Alternaria tenuissima, Bibolaris australiensis, Curvularia lunata, Nigrospora oryzae, Rhizopus oryzae, Stachybotrys chartrum, Syncephalastrum racemosum and Ulocladium botrytis. The biodiversity of fungi isolated from oil-contaminated soil was compared with previous studies. Brief descriptions of the new recorded fungi were given.

Chitosan Sensitivity of Fungi Isolated from Mango (Mangifera indica L.) with Anthracnose.

In Mexico, the mango crop is affected by anthracnose caused by Colletotrichum species. In the search for environmentally friendly fungicides, chitosan has shown antifungal activity. Therefore, fungal isolates were obtained from plant tissue with anthracnose symptoms from the state of Guerrero in Mexico and identified with the ITS and β-Tub2 genetic markers. Isolates of the Colletotrichum gloeosporioides complex were again identified with the markers ITS, Act, β-Tub2, GADPH, CHS-1, CaM, and ApMat. Commercial chitosan (Aldrich, lot # STBF3282V) was characterized, and its antifungal activity was evaluated on the radial growth of the fungal isolates. The isolated anthracnose-causing species were C. chrysophilum, C. fructicola, C. siamense, and C. musae. Other fungi found were Alternaria sp., Alternaria tenuissima, Fusarium sp., Pestalotiopsis sp., Curvularia lunata, Diaporthe pseudomangiferae, and Epicoccum nigrum. Chitosan showed 78% deacetylation degree and a molecular weight of 32 kDa. Most of the Colletotrichum species and the other identified fungi were susceptible to 1 g L−1 chitosan. However, two C. fructicola isolates were less susceptible to chitosan. Although chitosan has antifungal activity, the interactions between species of the Colletotrichum gloeosporioides complex and their effect on chitosan susceptibility should be studied based on genomic changes with molecular evidence.

Alternaria spp. Associated with Leaf Blight of Maize in Heilongjiang Province, China.

Maize (Zea mays L.) is a major economic crop worldwide. Maize can be infected by Alternaria species causing leaf blight that can result in significant economic losses. In this study, 168 Alternaria isolates recovered from symptomatic maize leaves were identified based on morphological characteristics, pathogenicity, and multilocus sequence analyses of the genes glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the internal transcribed spacer of ribosomal DNA (rDNA ITS), the RNA polymerase II second largest subunit (RPB2), and histone3 (HIS3). Maize isolates grouped to four Alternaria species including Alternaria tenuissima, A. alternata, A. burnsii, and Alternaria sp. Notably, A. tenuissima (71.4%) was the most prevalent of the four isolated species, followed by A. alternata (21.5%), Alternaria sp. (4.1%), and A. burnsii (3.0%). Pathogenicity tests showed that all four Alternaria species could produce elliptic to nearly round, or strip, lesions on leaves of maize, gray-white to dry white in the lesion centers and reddish-brown at the edges. The average disease incidence (58.47%) and average disease index (63.55) of maize leaves inoculated with A. alternata were significantly higher than levels resulting from A. tenuissima (55.28% and 58.49), Alternaria sp. (55.34% and 58.75), and A. burnsii (56% and 55). Haplotype analyses indicated that there were 14 haplotypes of A. tenuissima and five haplotypes of A. alternata in Heilongjiang Province and suggested the occurrence of a population expansion. Results of the study showed that Alternaria species associated with maize leaf blight in Heilongjiang Province are more diverse than those that have been previously reported. This is the first report globally of A. tenuissima, A. burnsii, and an unclassified Alternaria species as causal agents of leaf blight on maize.

Complete genome sequence of a novel partitivirus infecting the phytopathogenic fungus Alternaria tenuissima.

In the present study, a novel double-stranded RNA (dsRNA) mycovirus designated as "Alternaria tenuissima partitivirus 2" (AttPV2), was isolated from Alternaria tenuissima strain BJ-SY-1, a phytopathogenic fungus causing muskmelon leaf blight in Beijing municipality of China. The genome of AttPV2 comprises two dsRNA segments. The larger segment is 1829 bp in length and has a single open reading frame (ORF), potentially encoding a 65.8-kDa RNA-dependent RNA polymerase (RdRp), and the smaller segment is 1681 bp in length and also contains a single ORF, encoding a putative coat protein (CP) with a molecular mass of 56.0 kDa. BLASTp analysis revealed that the RdRp and CP encoded by the two ORFs of AttPV2 have the highest sequence identity, 85.9% and 75.0%, respectively, to their counterparts in Colletotrichum eremochloae partitivirus 1 (CePV1). Phylogenetic analysis based on RdRp sequences showed that AttPV2 clustered most closely with CePV1, a member of the proposed genus "Epsilonpartitivirus" in the family Partitiviridae. Hence, we propose that AttPV2 is a new epsilonpartitivirus from A. tenuissima. To the best of our knowledge, this is the first report of an epsilonpartitivirus infecting A. tenuissima.

The effect of barley infected with xylanase‐producing filamentous fungi on premature yeast flocculation

Premature yeast flocculation (PYF) is a sporadic problem in brewery fermentations that results in the incomplete utilisation of fermentable sugars. This work tests the hypothesis that barley or malt infected by xylanase-producing filamentous fungi contributes to premature yeast flocculation. Ten different fungi and yeasts were isolated and identified from malt and barley husk. These were inoculated onto barley husk and xylanase activity, arabinoxylan and the PYF value determined. The results from the fungal strains - Aureobasidium pullulans, Aspergillus flavus, Fusarium graminearum, and Alternaria tenuissima – indicated involvement in PYF. Small-scale malting and brewing was used to evaluate the PYF activity of fungal infected barley. The results showed that xylanase activity and arabinoxylan content were significantly (p < 0.05) related to PYF activity. With the exception of F. graminearum, xylanase activity was detected in the three other fungal isolates. The xylanases reduced the minimum concentration of arabinoxylan required for the induction of PYF. A small-scale brewing assay showed that xylanase secreted by the four filamentous fungi played a role in PYF. This research will contribute to the development of effective control strategies to prevent PYF factors in malt. © 2022 The Institute of Brewing & Distilling.

First Report of Alternaria tenuissima Causing Brown Spot Disease of Angelica dahurica in China.

Angelica dahurica (Fisch. ex Hoffm.) is an abundantly cultivated Chinese herbal medicine plant in China with about 4000 hectares grown, the annual production is up to 24,000 tons. The medicinal part of A. dahurica is its root, and mainly function for treat cold, headache, toothache, rhinitis, diabetes, etc. Besides, A. dahurica is also used as a spice in Asia. In September 2018, brown spot was observed on the leaves of A. dahurica in fields of Anguo City, Hebei Province, China. In the field investigated, the incidence of brown spot disease reached 15%. The infected leaves showed brown spots surrounded with pale yellow edge, resulting in withered of the whole leaf. It seriously endangers the growth of A. dahurica, reducing the yield and quality of medicinal materials, even leading to the death of plants. We isolated the pathogen from 10 leaves with same lesions, the small square leaf pieces of approximately 3 to 5 mm were obtained with the sterile scissors from the junction of infected and healthy tissues, sterilized with sodium hypochlorite (10%) for 1 min followed by washing in sterile water for 3 times, then incubated on potato dextrose agar (PDA) plates at 25°C for 4 days. The culture was transferred to new PDA plates and was cultivated in dark at 25°C for 10 days. A total of 3 species of fungi were isolated, and only one fungus species has been found to be able to cause the original pathological characteristics of A. dahurica leaves through the back-grafting experiment. The mycelium was black and began to sporulate after 8 days on PDA media by single spore separation. Multiple spores joined together to form spores chain. The spores were spindle-shaped, yellow to yellow brown, and size ranged from 45 to 55 × 15 to 20 µm (n=50), with zero to three longitudinal septa and one to five transverse septa. For pathogenicity tests, the spore suspension (3.5×105 spores/mL) were inoculated to healthy plants grown in experimental field, the test was repeated four times, and 10 leaves were inoculated in each repetition, and the sterile water was inoculated as the blank control. Inoculated leaves were covered with transparent plastic bags for 24 h to keep humidity. Nine days later, it was found that there were lesions on the leaves inoculated with the pathogen, and the traits were the same as those in the field, while the controls are healthy. The fungus was consistently isolated from the inoculated leaves. The similar isolates were re-isolated from the inoculated and infected leaves and identified as Alternaria tenuissima by DNA sequencing, fulfilling Koch's postulates. Fungal genomic DNA was extracted from 7-day-old culture. PCR amplifications were performed using primers ITS1 / ITS4 and TEFF / TEFR respectively (Takahashi et al. 2006, Du 2008). The nucleotide sequence of PCR products, which have been deposited in Genebank under the accession numbers MN153514 and MN735428, showed 99.8%-100% identity with the corresponding sequences of A. tenuissima (MW194297 and MK415954). In order to further identify the pathogen species, we constructed a phylogenetic tree by combining TEF sequence and ITS sequence to distinguish the relationship between the pathogen and other minor species in the genus Alternaria, the isolate was clustered in the Alternaria clade. Therefore, the pathogen was identified as A. tenuissima based on the morphological characteristics and molecular identification. To our knowledge, this is the first report of A. tenuissima causing leaf spot on A. dahurica in China.

Evolution of the spontaneous sourdoughs microbiota prepared with organic or conventional whole wheat flours from South Brazil

The purpose of this study was to compare the composition and stability of bacteria and fungi communities during the propagation of sourdoughs prepared with organic or conventional whole wheat (Triticum aestivum) flours from South Brazil. Sourdoughs were prepared and samples were collected during different fermentation times (0 to 216 h). Total DNA of sourdough samples were extracted and the 16S rRNA gene and Internal Transcribed Spacer region were sequenced by MiSeq-Illumina. A total of 43 and 56 OTUs were identified and defined as core taxa in the bacterial and fungal communities, respectively. The analysis revealed increases in the relative abundances of the lactic acid (Pediococcus pentosaceus, Weissella hellenica and Limosilactobacillus pontis) and acetic acid bacteria (Gluconobacter frateurii and Acetobacter tropicalis) during the sourdough propagation. The filaments fungi, Alternaria tenuissima, Fusarium culmorum, Fusarium petersiae and Microdochium seminicola remained more stable in organic than conventional during propagation cycles. After 216 h of fermentation, both sourdoughs were dominated by acid- and salt-tolerant yeast Issatchenkia orientalis (syn Pichia kudriavzevii, and Candida glycerinogenes). In conclusion, there were no significant differences in microbial communities among the sourdough samples. This study revealed that both flours contain autochthonous LAB, AAB, and yeasts with biotechnological applications in sourdough bread-making.

Linear Growth of Representatives of Wheat Seeds Mycobiota

Seed-born fungi of wheat interact with the plant at various stages of its development and with each other. With the highest growth rate, they should be isolated because of competition. The purpose of this study was to compare the growth of colonies on a nutrient medium for the gradation of fungal genera and species from wheat seeds according to aggressiveness. These data helped concluding on the effectiveness of mycoexpertise of winter wheat seeds. Potatoglucose agar (PGA) was used for the analysis of the fungal complex. Seven-day fungal cultures were sown in the centre of Petri dishes. Linear growth of fungal colonies on PGA with gentamicin was determined. The specific features of the development of 12 representatives of seeds mycobiota from the Northeast of Ukraine of the 2017-2019 harvest were investigated. The dominance of Alternaria sp. and a slight release of Fusarium sp. were established by analysis of the fungal complex. The first comparison of the linear growth of Fusarium graminearum, F. poae, and Alternaria tenuissima in 2017 showed that Fusarium colonies grow faster on nutrient medium. In 2018, the growth characteristics of A. arborescens, which quickly became dominant in wheat seeds mycoflora, and the littlecommon Trichothecium roseum were studied in detail. By comparing the growth of fast-growing F. graminearum with the common Aureobasidium pullulans and the aggressive Nigrospora oryzae, the fastest development of the third and the slowest of the second species was established. F. poae filled the Petri dish on day 6, Penicillium – on day 22. In 2019, in the first experiment comparing F. poae, F. sporotrichioides, and A. avenicola, the second species had the worst growth rates. It became the second fastest growing colony in the study of the growth of seven species in the second experiment. Isolates of N. oryzae in 2018 were more aggressive than in 2019. Specific features of colony growth on PGA did not affect the effectiveness of the analysis of mycobiota of winter wheat seeds. N. oryzae had the highest radial speed under the general dominance of Alternaria sp. Fusarium sp. (F. poae, F. sporotrichioides, F. verticillioides, and F. graminearum) and B. sorokiniana developed rapidly. A. arborescens and A. avenicola grew at the same level as A. pullulans. Penicillium and T. roseum lagged behind other fungi in speed and filled Petri dishes for the longest time. A. tenuissima had the lowest radial growth rate