Characterization of Alternaria blotch disease of apple in Himachal Pradesh, India: insights on morphology, pathogenicity, and molecular features.

BACKGROUND: Alternaria blotch disease in Himachal Pradesh, India, caused by Alternaria spp., adversely affects apple cultivars, resulting in reduced fruit size and quality accompanied by premature leaf fall. METHODS AND RESULTS: Sixteen Alternaria isolates from apple growing regions underwent comprehensive analysis including morphology, pathogenicity, and molecular characterization. Variations in conidiophore and conidia dimensions, shapes, and divisions were observed among isolates. Pathogenicity assays revealed differences in incubation periods, latent phases, and disease responses. Molecular characterization via nuclear ITS rDNA and RAPD analysis indicated 99-100% homology with Alternaria alternata, Alternaria mali, and other Alternaria spp., with a close phylogenetic relationship to Chinese isolates. Differentiation of isolates based on origin, cultural characteristics, and morphology was achieved using RAPD markers. CONCLUSIONS: The study identifies diverse genotypes and morphotypes of Alternaria contributing to apple blotch disease in Himachal Pradesh. These findings highlight the complexity of the pathogenic environment and hold significant implications for disease management in apple orchards.

Investigation on the presence of mycotoxins in seed hemp varieties.

In recent years, the cultivation of hemp (Cannabis sativa L.) in Europe has aroused interest among farmers for the potential market opportunities of its products; its cultivation has increased from 20,450 ha in 2015 to 33,020 ha in 2022. Thanks to the great versatility of this crop, there are opportunities in the food and nutraceutical fields (gluten free), cosmetics, energy and industrial sectors. As for several crops, hemp seeds may also be contaminated by fungal pathogens compromising its quality and safety. Considering the recent interest of consumers in using hemp for food purposes, in the present work, a small survey on mycotoxin contamination was carried out during 2018-2022 in hemp seed samples cultivated in Italy for food use. The results showed a limited occurrence of the most common regulated mycotoxins (aflatoxins [AFs], fumonisins [FBs], ochratoxin A [OTA], deoxynivalenol [DON] and zearalenone), but very high levels of alternariols, reaching a maximum value of 38510, 308, 226 and 288 ug/kg for tenuazonic acid [TeA], tentoxin [TEN], alternariol [AOH] and alternariol monoether, respectively. In the same period, an investigation carried out in an experimental field showed that fungal contamination and mycotoxin occurrence were influenced by different meteorological conditions and different varieties.

Fermentation of waste water from agar processing with Bacillus subtilis by metabolomic analysis.

Fungal infection has become a major threat to crop loss and affects food safety. The waste water from agar processing industries extraction has a number of active substances, which could be further transformed by microorganisms to synthesize antifungal active substances. In this study, Bacillus subtilis was used to ferment the waste water from agar processing industries extraction to analyze the antifungal activity of the fermentation broth on Alternaria alternata and Alternaria spp. Results showed that 25% of the fermentation broth was the most effective in inhibited A. alternata and Alternaria spp., with fungal inhibition rates of 99.9% and 96.1%, respectively, and a minimum inhibitory concentration (MIC) was 0.156 µg/mL. Metabolomic analysis showed that flavonoid polyphenols such as coniferyl aldehyde, glycycoumarin, glycitin, and procyanidin A1 may enhance the inhibitory activity against the two pathogenic fungal strains. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that polyphenols involved in the biosynthesis pathways of isoflavonoid and phenylpropanoid were upregulated after fermentation. The laser confocal microscopy analyses and cell conductivity showed that the cytoplasm of fungi treated with fermentation broth was destroyed. This study provides a research basis for the development of new natural antifungal agents and rational use of seaweed agar waste. KEY POINTS: • Bacillus subtilis fermented waste water has antifungal activity • Bacillus subtilis could transform active substances in waste water • Waste water is a potential raw material for producing antifungal agents.

Survey and toxigenic abilities of Aspergillus, Fusarium, and Alternaria fungi from wheat and paddy grains in Shanghai, China.

A systematic study was carried out on 638 wheat and paddy grains (including fresh and stored samples) collected in 2021 from Shanghai, China, to identify the major mycobiota and their toxigenic abilities. A total of 349 fungi, namely, 252 Fusarium, 53 Aspergillus, and 44 Alternaria, were characterized by morphological and molecular identification. Fusarium and Aspergillus were more frequently isolated in paddy with Fusarium sambucinum species complex and Aspergillus section flavi as the predominant species, respectively. The genus Alternaria was the most frequently isolated fungal species in wheat. The toxin-producing potentials of the identified fungi were further evaluated in vitro. Deoxynevalenol (DON) was produced by 34.5% of Fusarium isolates and zearalenone (ZEN) was produced by 47.6% of them, and one isolate also processed the abilities for fumonisin B1 (FB1), B2 (FB2), and B3 (FB3) productions. Aflatoxin B1 (AFB1), B2 (AFB2), and G1 (AFG1) were only generated by Aspergillus section flavi, with the production rate of 65.5%, 27.6%, and 13.8%, respectively. Alternariol (AOH) was the most prevalent Alternaria toxin, which could be produced by 95.5% of the isolates, followed by alternariol monomethyl ether (AME) (72.7%), altenuene (ALT) (52.3%), tenuazonic acid (TeA) (45.5%), tentoxin (TEN) (29.5%), and altenusin (ALS) (4.5%). A combinational analysis of mycobiota and toxigenic ability allowed us to provide comprehensive information about the production mechanisms of mycotoxins in wheat and paddy in a specific geographic area, and will be helpful for developing efficient prevention and control programs.

The Diversity of Fungal Endophytes from Wild Grape Vitis amurensis Rupr.

Grapevine endophytic fungi have great potential for application in agriculture and represent an important source of various compounds with valuable biological activities. Wild grapevine is known to host a great number of rare and unidentified endophytes and may represent a rich repository of potential vineyard biocontrol agents. This investigation aimed to study the fungal endophytic community of wild grape Vitis amurensis Rupr. using a cultivation-dependent (fungi sowing) and a cultivation-independent (next-generation sequencing, NGS) approach. A comprehensive analysis of the endophytic fungal community in different organs of V. amurensis and under different environmental conditions has been performed. According to the NGS analysis, 12 taxa of class level were presented in different grapevine organs (stem, leaf, berry, seed). Among the 12 taxa, sequences of two fungal classes were the most represented: Dothideomycetes-60% and Tremellomycetes-33%. The top five taxa included Vishniacozyma, Aureobasidiaceae, Cladosporium, Septoria and Papiliotrema. The highest number of fungal isolates and sequences were detected in the grape leaves. The present data also revealed that lower temperatures and increased precipitation favored the number and diversity of endophytic fungi in the wild Amur grape. The number of fungi recovered from grape tissues in autumn was two times higher than in summer. Thus, this study is the first to describe and analyze the biodiversity of the endophytic fungal community in wild grapevine V. amurensis.

Importance of Meteorological Parameters and Airborne Conidia to Predict Risk of Alternaria on a Potato Crop Ambient Using Machine Learning Algorithms.

Secondary infections of early blight during potato crop season are conditioned by aerial inoculum. However, although aerobiological studies have focused on understanding the key factors that influence the spore concentration in the air, less work has been carried out to predict when critical concentrations of conidia occur. Therefore, the goals of this study were to understand the key weather variables that affect the hourly and daily conidia dispersal of Alternaria solani and A. alternata in a potato field, and to use these weather factors in different machine learning (ML) algorithms to predict the daily conidia levels. This study showed that conidia per hour in a day is influenced by the weather conditions that characterize the hour, but not the hour of the day. Specifically, the relative humidity and solar radiation were the most relevant weather parameters influencing the conidia concentration in the air and both in a linear model explained 98% of the variation of this concentration per hour. Moreover, the dew point temperature three days before was the weather variable with the strongest effect on conidia per day. An improved prediction of Alternaria conidia level was achieved via ML algorithms when the conidia of previous days is considered in the analysis. Among the ML algorithms applied, the CART model with an accuracy of 86% were the best to predict daily conidia level.

Breakthrough Acute Necrotizing Invasive Fungal Rhinosinusitis by Alternariaalternata in a Patient with Acute Lymphoblastic Leukemia on Anidulafungin Therapy and Case-Based Literature Review.

Alternaria spp. have emerged as opportunistic pathogens particularly in immunosuppressed patients. A case of a breakthrough acute invasive fungal rhinosinusitis (AIFRS), caused by Alternaria alternata, is reported in a patient with acute lymphoblastic leukemia (ALL) on anidulafungin therapy, who was successfully treated with liposomal amphotericin B and surgical intervention. To date, 20 cases of AIFRS due to Alternaria spp. have been described, 19 in the USA and 1 in Chile, making this case report the first case of AIFRS due to Alternaria in Europe. The patients had median (range) age 25 (2-56) years (65% female), almost all of them (19/20) with hematological diseases and severe neutropenia (8-41 days pre-infection). Amphotericin B was the most frequently used antifungal agent, either alone or in combination. In all of the cases, systemic antifungal therapy was combined with surgery. Despite stabilization or improvement of the AIFRS, mortality was 38% (5 days to 8 months post-surgical debridement) due to their underlying disease or other infections without sign of AIFRS at autopsy.

Atypical Mycosis in Psittacine Birds: A Retrospective Study.

A retrospective study was conducted on parrots submitted from necropsy to the Department of Veterinary Pathology, School of Biosciences and Veterinary, University of Camerino, Italy, from 2007 to 2018. From a total of 2,153 parrots examined at post-mortem, four cases were diagnosed with atypical mycosis and were considered for determination of the fungus species by PCR. A Fischer's lovebird (Agapornis fischeri), Peach-faced lovebirds (Agapornis roseicollis), and two Blue and Gold Macaws (Ara ararauna) from four different aviaries died after some days of lethargy and ruffled feathers. Records of gross necropsy and histopathological exams (H&E, PAS, and Grocott stain) were described and biomolecular analyses were carried out. No specific gross lesions were appreciated at necropsy, while histopathology evidenced a systemic mycosis in several organs, particularly in the lungs. In affected organs, broad and non-septate hyphae, suggestive of mycoses, were observed. Molecularly, Mucor racemosus (Fischer's lovebird) and M. circinelloides (Peach-faced lovebirds) were identified from formalin-fixed and paraffin-embedded (FFPE) lung and liver tissue. In addition, Alternaria alternata and Fusicladium spp. (respectively in male and female Blue and Gold macaws) were identified in FFPE tissue from several organs; whereas the role of Mucor spp. as true pathogens is well-demonstrated, and the behavior of A. alternata and Fusicladium spp. in macaws as opportunistic pathogens have been discussed. To our knowledge, this report is the first one reporting mucormycosis caused by M. racemosus and M. circinelloides in lovebirds, and A. alternata and Fusicladium spp. in macaws.

Biocontrol of Carrot Disease-Causing Pathogens Using Essential Oils.

Diseases caused by fungal pathogens such as Alternaria spp. damage the commercial appearance of carrots or cause foliage diseases, resulting in significant yield losses each year and are a source of pre- and postharvest rots. European commission encourages the reduction of chemical pesticides. Therefore, the potential of essential oils for alternative plant protection is increasingly discussed. Furthermore, essential oils naturally produced by aromatic plants are rich in secondary metabolites, which possess several biological activities, and their use could be a significant step in environmentally friendly food production. This study aimed to evaluate the Origanum vulgare subsp. vulgare and Origanum vulgare subsp. hirtum essential oils efficacy on Alternaria spp. growth inhibition. A Clevenger-type apparatus was used to extract the essential oils from the fresh material. The Alternaria spp. radial colony growth was evaluated under essential oils concentrations from 200 to 600 µL L-1. Each essential oil separately was mixed with a PDA medium and Alternaria spp. disk placed in the center of the Petri dishes. Plates were incubated at 25 °C in the dark and evaluated 1, 2, 3, and 7 days after inoculation. The results revealed little difference between the essential oils, and the most effective concentration was 600 µL L-1 of O. vulgare subsp. vulgare essential oil and 400 µL L-1 of O. vulgare subsp. hirtum. Our findings can help to control carrot disease-causing pathogens Alternaria spp., but further research is needed.

Prevalence of the Alternaria blight of cumin (Cuminum cyminum L.) in Bangladesh: Morphology, phylogeny and pathogenic variation of Alternaria spp.

Cumin (Cuminum cyminum L.) is an important spice crop worldwide and its production is hampered by the infection of Alternaria blight. Cultivation of cumin in Bangladesh is very limited due to the lack of appropriate germplasm and adequate scientific information regarding the prevalence of Alternaria blight. Field trials were conducted with four advanced lines of cumin viz. CN026, CN028, CN031 and CN038 in five agro-ecological zones (AEZ) to know the adaptation possibility of these lines against the incidence and severity of Alternaria blight of cumin in Bangladesh. Among all lines, CN026 was found as the best in germination capacity and other yield parameters in all locations. The incidence and severity of the disease was observed as high as 98% and 88%, respectively, however, out of the five locations, the incidence and severity of the disease was the lowest in Bogura for the line CN026. In an attempt to identify the causal organism of the Alternaria blight of cumin by using molecular tools, a total of twenty three isolates were collected from the plants showing Alternaria blight symptoms from different AEZ in Bangladesh. Based on the molecular analysis, the isolates were identified as Alternaria alternata, A. burnsii, A. gaisen and A. tenuissima. A. alternata was the most prevalent species followed by A. tenuissima. The isolates of the identified species were found to have genetic, morphological and pathogenic variation. An isolate of A. alternata was observed as the most virulent among the isolates. This is the first report of A. alternata causing Alternaria blight disease of cumin in Bangladesh. The findings of this experiment will help in selecting suitable cumin germplasm and designing proper management strategies against Alternaria blight of cumin in Bangladesh.

Characterization of Fungi Associated with Olive Fruit Rot and Olive Oil Degradation in Crete, Southern Greece.

In November 2019, a severe outbreak of fruit rot was observed in olive orchards in Crete, southern Greece. Symptoms appeared primarily on fruits and stalks, resembling those caused by anthracnose. Typical symptoms were fruit rot, shrinkage, and mummification, associated commonly with stalk discoloration and fruit drop. Disease incidence was estimated at up to 100% in some cases, and an unprecedented increase in olive oil acidity reaching up to 8% (percentage of oleic acid) in severely affected olive groves was recorded. Thirty-two olive groves were then surveyed, and samples of fruit, stalk, leaf, and shoot were collected. Visual, stereoscopic, and microscopic observations revealed several fungi belonging to the genera Alternaria, Botryosphaeria, Capnodium, Colletotrichum, Fusarium, and Pseudocercospora. Fungal infection in fruits was commonly associated with concomitant infestation by the olive fruit fly Bactrocera oleae along with increased air temperature and relative humidity conditions that prevailed in October and November 2019. Twenty representative fungal strains isolated from symptomatic fruits and stalks were characterized by morphological, physiological, and molecular analyses. By internal transcribed spacer regions of ribosomal DNA region and translation elongation factor 1-α gene sequencing analysis, these isolates were identified as Alternaria spp., A. infectoria, Botryosphaeria dothidea, Colletotrichum boninense sensu lato, Fusarium lateritium, F. solani species complex and Stemphylium amaranthi. Pathogenicity tests on punctured fruits revealed that all isolates were pathogenic; however, F. solani isolates along with B. dothidea were the most virulent, and wounds were necessary for efficient fungal infection. Moreover, as few as 10 spores of F. solani were sufficient to cause significant infection in punctured fruits. F. solani was also capable of infecting olive fruits in the presence of B. oleae, with no additional wounding, in artificial inoculation experiments. Moreover, it was capable of colonizing and affecting olive blossoms. Further analyses of olive oil extracted from fruits artificially inoculated with F. solani indicated a significant increase in oil acidity, K232, K270, and peroxide value, whereas total phenol content was significantly decreased. To the best of our knowledge, this is the first report of F. solani associated with olive fruit rot and olive oil degradation worldwide.

Morphological and Molecular Characterization of Alternaria spp. Isolated from European Pears.

In a recent survey of post-harvest rot pathogens in European pear in Southern Oregon, Alternaria spp. were frequently isolated from orchard samples of pear flowers and fruits. Morphological differences were observed within the isolated cultures. A preliminary NCBI BLAST search analysis using sequences of the ATPase locus across 94 isolates of Alternaria spp. obtained from pear fruit rots revealed three major Alternaria sections: sect. Alternata, sect. Infectoriae, and sect. Ulocladioides. Thirteen isolates were selected based on their genetic and morphological diversity across three Alternaria sections and were subjected to multilocus phylogenetic analysis using sequences from plasma membrane ATPase, calmodulin, and Alt a1 loci. Within sect. Alternata, four Alternaria arborescens isolates and one A. destruens isolate were identified; within sections Infectoriae and Ulocladioides, one A. rosae isolate and two A. botrytis isolates were identified, respectively. The remaining five isolates could not be identified based on the available sequences for the three loci used in this study. In addition to the phylogenetic analysis, pathogenicity assays revealed differential responses to these isolates on four pear cultivars: Anjou, Bartlett, Comice, and Bosc. Inoculation of isolates within Alternaria sect. Alternata resulted in fruit lesions across all cultivars, with Bosc pear being significantly susceptible (P < 0.0001). Isolates within Alternaria sect. Ulocladioides caused rots on Anjou and Bosc pears, while isolates within Alternaria sect. Infectoriae developed rots on Bosc pear only. This study suggests that there is differential susceptibility of pear cultivars to Alternaria rots, and the severity of post-harvest rot depends on the type of Alternaria spp. and cultivar predominant in a region.

Co-occurrence of mycotoxins, aflatoxin biosynthetic precursors, and Aspergillus metabolites in garlic (Allium sativum L) marketed in Zaria, Nigeria.

Multi-mycotoxin analysis of 72 samples of garlic bulbs sold in Zaria markets was carried out using a liquid chromatography-mass spectrometry (LC-MS/MS) method. The results indicated the presence of seven major mycotoxins, including aflatoxin B1 (AFB1), ochratoxin A (OTA), and the fumonisins B1, B2, B3, B4, and B6, at different levels of contamination. AFB1 and OTA were detected in 1 of the 72 samples (1.4%) with median concentrations of 5.48 and 12.3 µg/kg, respectively. FB1 and FB2 were detected in 77% and 100% of the analysed samples, with median concentrations of 401 µg/kg and 491 µg/kg, respectively. The observed levels of AFB1, OTA, FB1, and FB2 were above the EU maximum limit in herbal products. Sterigmatocystin (STC), an AFB1 biosynthetic precursor, was present in all tested samples. The contamination level of mycotoxins and Aspergillus metabolites of marketed garlic in the study area is of public health concern.

Fungal endophyte diversity in table grapes.

Plant fungal endophytes are diverse microbial sources that reside inside plants. Grapes (Vitis vinifera) are rich in polyphenols that have beneficial health effects, and recent research has shown that fungal endophytes in grapes may contribute to the production of these polyphenols and may serve as biocontrol agents. In this study, we determined the fungal microbial endophyte diversity in North American table grapes found at a Winnipeg, Manitoba, market. The amplicon internal transcribed spacer (ITS) metagenomics approach was used to profile the fungal communities of the fruit endophyte microbiome of three table grape types. The data supported endophyte diversity in different table grapes, including possible bioactive, saprophytic, and pathogenic fungi. Culturable endophytes were isolated and identified by morphology and ITS amplicon sequencing. The majority of the isolated culturable strains included Alternaria spp. and Cladosporium spp. The results provided evidence of the existence of diverse fungal endophytes isolated and identified from the fruit of the table grapes. These fungal endophytes may have potential in agricultural, industrial, and pharmaceutical applications.

A novel nano-sulphur and essential oil-based room freshener

Introducción: Alternaria spp y Candida spp. son hongos patógenos de ambientes interiores como la casa, la oficina, el aula, etc., causan enfermedades como asma crónica e infecciones sistémicas en individuos inmunodeprimidos a través de la secreción de diversas sustancias tóxicas. Los ambientadores a base de productos químicos disponibles comercialmente que se utilizan para controlar la carga de hongos en el ambiente interior no son beneficiosos para la salud humana. Objetivo: proporcionar una alternativa viable en forma de enfoque basado en nanopartículas para el manejo de hongos transmitidos por el aire. Metodología: aislamiento, identificación microscópica y bioquímica de hongos de interior; Síntesis de nanopartículas de azufre (SNP) mediadas por Azadirachta indica, su detección y caracterización; y evaluación in vitro de SNP contra hongos aislados presentes en el ambiente interior. Resultado: Los hongos aislados se identificaron como especies de Alternaria spp y Candida spp. Los SNP mostraron máximos de absorbancia a 291 nm. El análisis NTA mostró un tamaño medio de 188,4 nm y un potencial zeta de -4,94 mV, lo que representa una síntesis de SNP estables. El patrón XRD confirmó la naturaleza cristalina cúbica centrada en la cara de los SNP. El espectro FTIR representó la presencia de compuestos polihidroxilo, nitrilo, ceto, aromáticos y carboxílicos que estabilizaron los SNP. Los ensayos antifúngicos demostraron la actividad significativa de los SNP formulados y del ambientador infundido con aceite de eucalipto. Conclusión: Los SNP mediados por A. indica se pueden aplicar en la formulación y fabricación de un ambientador ecológico para el manejo de hongos patógenos de interior como Alternaria spp y Candida spp.

Introduction: Alternaria spp. and Candida spp. are the main fungal pathogen of indoor environment like house, office, classroom, etc. These may cause various diseases and infections like systemic infections, or chronic asthma in immunocompromised individuals through secretion of various toxic substances. Chemical-based commercially available room fresheners used to control the fungal load of indoor environment are not beneficial to human health. Objective: was to provide viable alternative in the form of nanoparticle-based approach for the management of air-borne fungi. Methodology: The present study primarily focuses on the isolation, microscopic and biochemical identification of indoor fungi; Azadirachta indica-mediated sulphur nanoparticles (SNPs) synthesis, their detection and characterization; and in vitro assessment of SNPs against isolated fungi present in indoor environment. Result: The isolated fungi were identified as Alternaria spp and Candida spp. The SNPs showed absorbance maxima at 291 nm. NTA analysis showed average size of 188.4 nm, and zeta potential of -4.94 mV which represented synthesis of stable SNPs. XRD pattern confirmed the face centered cubic, crystalline nature of SNPs. FTIR spectrum depicted the presence of polyhydroxyl, nitrile, keto, aromatic and carboxylic compounds which stabilized the SNPs. The antifungal assays demonstrated the significant activity of the formulated SNPs and eucalyptus oil infused air freshener. Conclusion: It can be concluded that A. indica-mediated SNPs can be applied in the formulation and manufacture of an ecofriendly air freshener for the management of indoor fungal pathogens like Alternaria spp. and Candida spp.

Cytotoxic secondary metabolites from the vulnerable conifer Cephalotaxus oliveri and its associated endophytic fungus Alternaria alternate Y-4-2.

Rare and endangered plants (REPs) and their associated endophytes survived in unique habitats are promising sources for natural product-derived drug discovery. In this study, six new (cephaloverines A-F, 1-6, resp.) and 16 known (11-26) cephalotaxine-type alkaloids, together with three new (oliverbiflavones A-C, 7-9, resp.) and 11 known (27-37) biflavonoids were isolated and characterized from the twigs and leaves of Cephalotaxus oliveri, an endangered plant endemic to China. Meanwhile, a preliminary investigation on the secondary metabolites from a selected fungal endophyte (i.e., Alternaria alternate Y-4-2) associated with the title plant led to the isolation of 21 structurally distinct polyketides including one new dimeric xanthone (10). The new structures (1-10) with the absolute configurations were determined by detailed spectroscopic analyses, electronic circular dichroism (ECD) or Na2MoO4-induced ECD, the modified Mosher's method, and some chemical transformations. Compounds 1-4 are the first representatives of naturally occurring N-oxides of cephalotaxine esters, while compounds 7-9 have a special structural feature of having a C-methylated biflavonoid skeleton. The Cephalotaxus alkaloids with ester side-chains at C-3 (1-6, 13-22, and 26) and four biflavonoids (27-29 and 34) were found to show pronounced cytotoxicities against a small panel of human cancer cell lines (A549, NCI-H460, HL60, NCI-H929, and RPMI-8226), with IC50 values mainly ranging from 0.003 to 9.34 µM. The most potent compound, deoxyharringtonine (16), generally exhibited IC50 values less than 10 nM. The structure-activity relationship (SAR) of the aforementioned Cephalotaxus alkaloids was briefly discussed.

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Methanol, ethyl acetate, and water were used to extract the continuous cropping soils of Panax notoginseng, with the solution/soil ratios of 3:1, 6:1, and 9:1. We investigated the effects of those soil extracts on the growth and population of root-rot pathogens of P. notoginseng. Results showed that the methanol, ethyl acetate and water extracts all promoted mycelial growth of Fusarium oxysporum and Fusarium solani after 72 h of plate culture. The response indices of methanol and ethyl acetate extracts on the growth of F. oxysporum were 14.0%-19.8% and 16.2%-20.2%, being higher than that of water extract (8.9%-14.2%), but without significant difference between diffe-rent extraction ratios. However, methanol extract inhibited the mycelial growth of Alternaria spp. The inhibitory effect was highest at the extraction ratio of 3:1, reaching -33.2% to -38.5%. Ethyl acetate and water extracts did not affect the mycelial growth of Alternaria spp. After four weeks of soil culture, methanol, ethyl acetate and water extracts all increased the F. oxysporum populations. The positive effect of water extract was higher than that of methanol (1.68×104-6.73×104 copies·g-1 dry soil) and ethyl acetate (1.77×104-3.72×104 copies·g-1 dry soil) extracts, being 3.49×106-9.56×106 copies·g-1 dry soil. This increment was weakened along with the increase of extraction ratio. Both water extract and methanol extract with low extraction ratio could increase the F. solani populations, while there were no significant effects of methanol, ethyl acetate and water extracts on the population of Alternaria spp. Therefore, the extracts from continuous P. notoginseng cropping soil showed allopathically promoting effects on the growth and population of root-rot pathogens, F. oxysporum and F. solani, which may be one of the reasons for the occurrence of root rot and other soil-borne diseases in replanted P. notoginseng gardens.

Fullerol C60(OH)24 Nanoparticles Affect Secondary Metabolite Profile of Important Foodborne Mycotoxigenic Fungi In Vitro.

Despite the efforts to control mycotoxin contamination worldwide, extensive contamination has been reported to occur in food and feed. The contamination is even more intense due to climate changes and different stressors. This study examined the impact of fullerol C60(OH)24 nanoparticles (FNP) (at 0, 1, 10, 100, and 1000 ng mL-1) on the secondary metabolite profile of the most relevant foodborne mycotoxigenic fungi from genera Aspergillus, Fusarium, Alternaria and Penicillium, during growth in vitro. Fungi were grown in liquid RPMI 1640 media for 72 h at 29 °C, and metabolites were investigated by the LC-MS/MS dilute and shoot multimycotoxin method. Exposure to FNP showed great potential in decreasing the concentrations of 35 secondary metabolites; the decreases were dependent on FNP concentration and fungal genus. These results are a relevant guide for future examination of fungi-FNP interactions in environmental conditions. The aim is to establish the exact mechanism of FNP action and determine the impact such interactions have on food and feed safety.

Enzymatic Synthesis of Modified Alternaria Mycotoxins Using a Whole-Cell Biotransformation System.

Reference standards for Alternaria mycotoxins are rarely available, especially the modified mycotoxins alternariol-3-glucoside (AOH-3-G), alternariol-9-glucoside (AOH-9-G), and alternariol monomethylether-3-glucoside (AME-3-G). To obtain these three glucosides as analytical standards for method development and method validation, alternariol and alternariol monomethylether were enzymatically glycosylated in a whole-cell biotransformation system using a glycosyltransferase from strawberry (Fragaria x ananassa), namely UGT71A44, expressed in Escherichia coli (E. coli). The formed glucosides were isolated, purified, and structurally characterized. The exact amount of the isolated compounds was determined using high-performance liquid chromatography with UV-detection (HPLC-UV) and quantitative nuclear resonance spectroscopy (qNMR). This method has proved to be highly effective with biotransformation rates of 58% for AOH-3-G, 5% for AOH-9-G, and 24% for AME-3-G.

Comparative genomics of Alternaria species provides insights into the pathogenic lifestyle of Alternaria brassicae - a pathogen of the Brassicaceae family.

BACKGROUND: Alternaria brassicae, a necrotrophic pathogen, causes Alternaria Leaf Spot, one of the economically important diseases of Brassica crops. Many other Alternaria spp. such as A. brassicicola and A. alternata are known to cause secondary infections in the A. brassicae-infected Brassicas. The genome architecture, pathogenicity factors, and determinants of host-specificity of A. brassicae are unknown. In this study, we annotated and characterised the recently announced genome assembly of A. brassicae and compared it with other Alternaria spp. to gain insights into its pathogenic lifestyle. RESULTS: We also sequenced the genomes of two A. alternata isolates that were co-infecting B. juncea using Nanopore MinION sequencing for additional comparative analyses within the Alternaria genus. Genome alignments within the Alternaria spp. revealed high levels of synteny between most chromosomes with some intrachromosomal rearrangements. We show for the first time that the genome of A. brassicae, a large-spored Alternaria species, contains a dispensable chromosome. We identified 460 A. brassicae-specific genes, which included many secreted proteins and effectors. Furthermore, we have identified the gene clusters responsible for the production of Destruxin-B, a known pathogenicity factor of A. brassicae. CONCLUSION: The study provides a perspective into the unique and shared repertoire of genes within the Alternaria genus and identifies genes that could be contributing to the pathogenic lifestyle of A. brassicae.