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International Journal of Biometeorology Jun 2023Alternaria is a plant pathogen and human allergen. Alternaria alternata is one of the most abundant fungal spores in the air. The purpose of this study was to examine...
Using qPCR and microscopy to assess the impact of harvesting and weather conditions on the relationship between Alternaria alternata and Alternaria spp. spores in rural and urban atmospheres.
Alternaria is a plant pathogen and human allergen. Alternaria alternata is one of the most abundant fungal spores in the air. The purpose of this study was to examine whether Alternaria spp. spore concentrations can be used to predict the abundance and spatio-temporal pattern of A. alternata spores in the air. This was investigated by testing the hypothesis that A. alternata dominates airborne Alternaria spp. spores and varies spatio-temporally. Secondarily, we aimed at investigating the relationship between airborne Alternaria spp. spores and the DNA profile of A. alternata spores between two proximate (~ 7 km apart) sites. These were examined by sampling Alternaria spp. spores using Burkard 7-day and cyclone samplers for the period 2016-2018 at Worcester and Lakeside campuses of the University of Worcester, UK. Daily Alternaria spp. spores from the Burkard traps were identified using optical microscopy whilst A. alternata from the cyclone samples was detected and quantified using quantitative polymerase chain reaction (qPCR). The results showed that either A. alternata or other Alternaria species spores dominate the airborne Alternaria spore concentrations, generally depending on weather conditions. Furthermore, although Alternaria spp. spore concentrations were similar for the two proximate sites, A. alternata spore concentrations significantly varied for those sites and it is highly likely that the airborne samples contained large amounts of small fragments of A. alternata. Overall, the study shows that there is a higher abundance of airborne Alternaria allergen than reported by aerobiological networks and the majority is likely to be from spore and hyphal fragments.
Topics: Humans; Alternaria; Spores, Fungal; Microscopy; Air Microbiology; Weather; Allergens
PubMed: 37191729
DOI: 10.1007/s00484-023-02480-w -
Toxins Jul 2021The tomato is one of the most consumed agri-food products in Lebanon. Several fungal pathogens, including species, can infect tomato plants during the whole growing...
The tomato is one of the most consumed agri-food products in Lebanon. Several fungal pathogens, including species, can infect tomato plants during the whole growing cycle. infections cause severe production and economic losses in field and during storage. In addition, species represent a serious toxicological risk since they are able to produce a wide range of mycotoxins, associated with different toxic activities on human and animal health. Several species were detected on tomatoes, among which the most important are , , and . A set of 49 strains isolated from leaves and stems of diseased tomato plants were characterised by using a polyphasic approach. All strains were included in the recently defined phylogenetic section and grouped in three well-separated sub-clades, namely (24 out of 49), (12 out of 49), and morpho-species (12 out of 49). One strain showed high genetic similarity with an reference strain. Chemical analyses showed that most of the strains, cultured on rice, were able to produce alternariol (AOH), alternariol methyl ether (AME), altenuene (ALT) and tenuazonic acid (TA), with values up to 5634, 16,006, 5156, and 4507 mg kg, respectively. In addition, 66% of the strains were able to co-produce simultaneously the four mycotoxins investigated. The pathogenicity test carried out on 10 strains, representative of phylogenetic sub-clades, revealed that they were all pathogenic on tomato fruits. No significant difference among strains was observed, although and strains were slightly more aggressive than morpho-species strains. This paper reports new insights on mycotoxin profiles, genetic variability, and pathogenicity of species on tomatoes.
Topics: Alternaria; Fruit; Lebanon; Solanum lycopersicum; Mycotoxins; Phylogeny; Plant Diseases
PubMed: 34437384
DOI: 10.3390/toxins13080513 -
The Science of the Total Environment Apr 2022Fungal spores make up a significant proportion of organic matter within the air. Allergic sensitisation to fungi is associated with conditions including allergic fungal... (Review)
Review
Fungal spores make up a significant proportion of organic matter within the air. Allergic sensitisation to fungi is associated with conditions including allergic fungal airway disease. This systematic review analyses outdoor fungal spore seasonality across Europe and considers the implications for health. Seventy-four studies met the inclusion criteria, the majority of which (n = 64) were observational sampling studies published between 1978 and 2020. The most commonly reported genera were the known allergens Alternaria and Cladosporium, measured in 52 and 49 studies, respectively. Both displayed statistically significant increased season length in south-westerly (Mediterranean) versus north-easterly (Atlantic and Continental) regions. Although there was a trend for reduced peak or annual Alternaria and Cladosporium spore concentrations in more northernly locations, this was not statistically significant. Peak spore concentrations of Alternaria and Cladosporium exceeded clinical thresholds in nearly all locations, with median peak concentrations of 665 and 18,827 per m, respectively. Meteorological variables, predominantly temperature, precipitation and relative humidity, were the main factors associated with fungal seasonality. Land-use was identified as another important factor, particularly proximity to agricultural and coastal areas. While correlations of increased season length or decreased annual spore concentrations with increasing average temperatures were reported in multi-decade sampling studies, the number of such studies was too small to make any definitive conclusions. Further, up-to-date studies covering underrepresented geographical regions and fungal taxa (including the use of modern molecular techniques), and the impact of land-use and climate change will help address remaining knowledge gaps. Such knowledge will help to better understand fungal allergy, develop improved fungal spore calendars and forecasts with greater geographical coverage, and promote increased awareness and management strategies for those with allergic fungal disease.
Topics: Air Microbiology; Alternaria; Environmental Monitoring; Europe; Seasons; Spores, Fungal
PubMed: 34800445
DOI: 10.1016/j.scitotenv.2021.151716 -
Toxins Nov 2022As a filamentous and spoilage fungus, spp. can not only infect processing tomatoes, but also produce a variety of mycotoxins which harm the health of human beings. To...
As a filamentous and spoilage fungus, spp. can not only infect processing tomatoes, but also produce a variety of mycotoxins which harm the health of human beings. To explore the production of toxins in processing tomatoes during growth and storage, four main toxins and four conjugated toxins were detected by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and ultra-performance liquid chromatography-ion mobility quadrupole time-of-flight mass spectrometry (UPLC-IMS QToF MS) in processing tomatoes on different days after being inoculated with . The results show that the content of toxins in an in vivo assay is higher than that under field conditions. Tenuazonic acid (TeA) is the predominant toxin detected in the field (205.86~41,389.19 μg/kg) and in vivo (7.64~526,986.37 μg/kg) experiments, and the second-most abundant toxin is alternariol (AOH). In addition, a small quantity of conjugated toxins, AOH-9-glucoside (AOH-9-Glc) and alternariol monomethyl ether-3-glucoside (AME-3-Glc), were screened in the in vivo experiment. This is the first time the potential of toxins produced in tomatoes during the harvest period has been studied in order to provide data for the prevention and control of toxins.
Topics: Humans; Chromatography, Liquid; Alternaria; Solanum lycopersicum; Food Contamination; Tandem Mass Spectrometry; Mycotoxins; Toxins, Biological; Lactones
PubMed: 36548724
DOI: 10.3390/toxins14120827 -
Pest Management Science Sep 2021Alternaria species are well-known aggressive pathogens that are widespread globally and warmer temperatures caused by climate change might increase their abundance more... (Review)
Review
Alternaria species are well-known aggressive pathogens that are widespread globally and warmer temperatures caused by climate change might increase their abundance more drastically. Early blight (EB) disease, caused mainly by Alternaria solani, and brown spot, caused by Alternaria alternata, are major concerns in potato, tomato and eggplant production. The development of EB is strongly linked to varieties, crop development stages, environmental factors, cultivation and field management. Several forecasting models for pesticide application to control EB were created in the last century and more recent scientific advances have included modern breeding technology to detect resistant genes and precision agriculture with hyperspectral sensors to pinpoint damage locations on plants. This paper presents an overview of the EB disease and provides an evaluation of recent scientific advances to control the disease. First of all, we describe the outline of this disease, encompassing biological cycles of the Alternaria genus, favorite climate and soil conditions as well as resistant plant species. Second, versatile management practices to minimize the effect of this pathogen at field level are discussed, covering their limitations and pitfalls. A better understanding of the underlying factors of this disease and the potential of novel research can contribute to implementing integrated pest management systems for an ecofriendly farming system. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Topics: Agriculture; Alternaria; Pest Control; Plant Breeding; Plant Diseases
PubMed: 33538396
DOI: 10.1002/ps.6320 -
Mycotoxin Research May 2023Fungi of the genus Alternaria are ubiquitous in the environment. Their mycotoxins can leach out of contaminated plants or crop debris into the soil entering the plant...
Fungi of the genus Alternaria are ubiquitous in the environment. Their mycotoxins can leach out of contaminated plants or crop debris into the soil entering the plant via the roots. We aim to evaluate the importance of this entry pathway and its contribution to the overall content of Alternaria toxins (ATs) in wheat plants to better understand the soil-plant-phytopathogen system. A hydroponic cultivation system was established and wheat plants were cultivated for up to two weeks under optimal climate conditions. One half of the plants was treated with a nutrient solution spiked with alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA), whereas the other half of the plants was cultivated without mycotoxins. Plants were harvested after 1 and 2 weeks and analyzed using a QuEChERS-based extraction and an in-house validated LC-MS/MS method for quantification of the ATs in roots, crowns, and leaves separately. ATs were taken up by the roots and transported throughout the plant up to the leaves after 1 as well as 2 weeks of cultivation with the roots showing the highest ATs levels followed by the crowns and the leaves. In addition, numerous AOH and AME conjugates like glucosides, malonyl glucosides, sulfates, and di/trihexosides were detected in different plant compartments and identified by high-resolution mass spectrometry. This is the first study demonstrating the uptake of ATs in vivo using a hydroponic system and whole wheat plants examining both the distribution of ATs within the plant compartments and the modification of ATs by the wheat plants.
Topics: Chromatography, Liquid; Alternaria; Triticum; Hydroponics; Food Contamination; Tandem Mass Spectrometry; Mycotoxins; Lactones; Soil
PubMed: 36929507
DOI: 10.1007/s12550-023-00477-3 -
MBio Jun 2022Contamination of food and feed with toxin-producing fungi is a major threat in agriculture and for human health. The filamentous fungus Alternaria alternata is one of...
Contamination of food and feed with toxin-producing fungi is a major threat in agriculture and for human health. The filamentous fungus Alternaria alternata is one of the most widespread postharvest contaminants and a weak plant pathogen. It produces a large variety of secondary metabolites with alternariol and its derivatives as characteristic mycotoxin. Other important phyto- and mycotoxins are perylene quinones (PQs), some of which have anticancer properties. Here, we discovered that the PQ altertoxin (ATX) biosynthesis shares most enzymes with the 1,8-dihydroxynaphthalene (1,8-DHN) melanin pathway. However, melanin was formed in aerial hyphae and spores, and ATXs were synthesized in substrate hyphae. This spatial separation is achieved through the promiscuity of a polyketide synthase, presumably producing a pentaketide (T4HN), a hexaketide (AT4HN), and a heptaketide (YWA1) as products. T4HN directly enters the altertoxin and DHN melanin pathway, whereas AT4HN and YWA1 can be converted only in aerial hyphae, which probably leads to a higher T4HN concentration, favoring 1,8-DHN melanin formation. Whereas the production of ATXs was strictly dependent on the CmrA transcription factor, melanin could still be produced in the absence of CmrA to some extent. This suggests that different cues regulate melanin and toxin formation. Since DHN melanin is produced by many fungi, PQs or related compounds may be produced in many more fungi than so far assumed. Mycotoxins are a major threat for human health. Food safety control relies on the identification of the toxins or the detection of the expression of the respective genes. The latter method, however, relies on the knowledge of the biosynthetic pathway and the key genes. Alternaria alternata is a major food contaminant and produces many different mycotoxins with altertoxins and other perylene quinones as prominent examples. Here, we discovered that the biosynthetic pathway for altertoxins shares most of the enzymes with the dihydroxynaphthalene (DHN) melanin pathway. Because the DHN melanin pathway is widespread among fungi, the production of mycotoxins of the perylene quinone class could be more widespread than so far anticipated.
Topics: Alternaria; Humans; Melanins; Mycotoxins; Perylene; Quinones
PubMed: 35475649
DOI: 10.1128/mbio.00219-22 -
Biomedica : Revista Del Instituto... Aug 2023Fungal genera Alternaria and Fusarium include human and plant pathogenic species. Several antifungals have been used for their control, but excessive use has contributed...
In vitro and Quantitative and Structure Activity Relationship (QSAR) evaluation of the antifungal activity of terpenoid constituents of essential oils against Alternaria alternata and Fusarium oxysporum.
INTRODUCTION
Fungal genera Alternaria and Fusarium include human and plant pathogenic species. Several antifungals have been used for their control, but excessive use has contributed to resistance development in pathogens. An alternative to searching for and developing new antifungal agents is using essential oils and their main components, which have biological activities of interest in medicine and food production.
OBJECTIVE
To evaluate in vitro and in silico the antifungal activities of terpenoids against Alternaria alternata and Fusarium oxysporum.
MATERIALS AND METHODS
The minimum inhibitory concentration and minimum fungicidal concentration values of 27 constituents of essential oils used against Alternaria alternata and Fusarium oxysporum were evaluated in vitro. In addition, using genetic algorithms, quantitative models of the structure-activity relationship were used to identify the structural and physicochemical properties related to antifungal activity.
RESULTS
The evaluated compounds proved to be effective antifungals. Thymol was the most active with a minimum inhibitory concentration of 91.6 ± 28.8 μg/ml for A. alternata and F. oxysporum. Quantitative structure-activity relationship models revealed the octanolwater cleavage ratio as the molecular property, and the phenols as the main functional group contributing to antifungal activity.
CONCLUSION
Terpenoids exhibit relevant antifungal activities that should be incorporated into the study of medicinal chemistry. Inclusion of in silico assays in the in vitro evaluation is a valuable tool in the search for and rational design of terpene derivatives as new potential antifungal agents.
Topics: Humans; Quantitative Structure-Activity Relationship; Antifungal Agents; Alternaria; Fusarium; Oils, Volatile; Terpenes
PubMed: 37721910
DOI: 10.7705/biomedica.6883 -
Brazilian Journal of Microbiology :... 2013The objectives of this study were to evaluate the ability to produce alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by A. alternata and...
The objectives of this study were to evaluate the ability to produce alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by A. alternata and A. infectoria strains recovered from wheat kernels obtained from one of the main production area in Argentina; to confirm using AFLPs molecular markers the identify of the isolates up to species level, and to evaluate the intra and inter-specific genetic diversity of these two Alternaria species. Among all the Alternaria strains tested (254), 84% of them were able to produce mycotoxins. The most frequent profile of toxin production found was the co-production of AOH and AME in both species tested. TA was only produced by strains of A. alternata. Amplified fragment polymorphism (AFLPs) analysis was applied to a set of 89 isolates of Alternaria spp (40 were A. infectoria and 49 were A. alternata) in order to confirm the morphological identification. The results showed that AFLPs are powerful diagnostic tool for differentiating between A. alternata and A. infectoria. Indeed, in the current study the outgroup strains, A. tenuissima was consistently classified. Characteristic polymorphic bands separated these two species regardless of the primer combination used. Related to intraspecific variability, A. alternata and A. infectoria isolates evaluated seemed to form and homogeneous group with a high degree of similarity among the isolates within each species. However, there was more scoreable polymorphism within A. alternata than within A. infectoria isolates. There was a concordance between morphological identification and separation up to species level using molecular markers. Clear polymorphism both within and between species showed that AFLP can be used to asses genetic variation in A. alternata and A. infectoria. The most important finding of the present study was the report on AOH and AME production by A. infectoria strains isolated from wheat kernels in Argentina on a semisynthetic media for the first time. Also, specific bands for A. alternata and A. infectoria have been identified; these may be useful for the design of specific PCR primers in order to differentiate these species and to detect them in cereals.
Topics: Alternaria; Amplified Fragment Length Polymorphism Analysis; Argentina; Genetic Variation; Molecular Typing; Mycological Typing Techniques; Mycotoxins; Triticum
PubMed: 24294236
DOI: 10.1590/S1517-83822013000200017 -
Microbiological Research Mar 2022The ability to cope with environmental abiotic stress and biotic stress is crucial for the survival of plants and microorganisms, which enable them to occupy multiple...
The ability to cope with environmental abiotic stress and biotic stress is crucial for the survival of plants and microorganisms, which enable them to occupy multiple niches in the environment. Previous studies have shown that transcription factors play crucial roles in regulating various biological processes including multiple stress tolerance and response in eukaryotes. This work identified multiple critical transcription factor genes, metabolic pathways and gene ontology (GO) terms related to abiotic stress response were broadly activated by analyzing the transcriptome of phytopathogenic fungus Alternaria alternata under metal ions stresses, oxidative stress, salt stresses, and host-pathogen interaction. We investigated the biological functions and regulatory roles of the bZIP transcriptional factor (TF) genes in the phytopathogenic fungus A.alternata by analyzing targeted gene disrupted mutants. Morphological analysis provides evidence that the bZIP transcription factors (Gcn4, MeaB, Atf1, the ER stress regulator Hac1, and the all development altered-1 gene Ada1) are required for morphogenesis as the colony morphology of these gene deletion mutants was significantly different from that of the wild-type. In addition, bZIPs are involved in the resistance to multiple stresses such as oxidative stress (Ada1, Yap1, MetR) and virulence (Hac1, MetR, Yap1, Ada1) at varying degrees. Transcriptome data demonstrated that the inactivation of bZIPs (Hac1, Atf1, Ada1 and Yap1) significantly affected many genes in multiple critical metabolism pathways and gene ontology (GO) terms. Moreover,the ΔHac1 mutants displayed reduced aerial hypha and are hypersensitivity to endoplasmic reticulum disruptors such as tunicamycin and dithiothreitol. Transcriptome analysis showed that inactivation of Hac1 significantly affected the proteasome process and its downstream unfolded protein binding, indicating that Hac1 participates in the endoplasmic reticulum stress response through the conserved unfolded protein response. Taken together, our findings reveal that bZIP transcription factors function as key regulators of fungal morphogenesis, abiotic stress response and pathogenesis, and expand our understanding of how microbial pathogens utilize these genes to deal with environmental stresses and achieve successful infection in the host plant.
Topics: Alternaria; Basic-Leucine Zipper Transcription Factors; Fungal Proteins; Stress, Physiological
PubMed: 34953292
DOI: 10.1016/j.micres.2021.126915