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Molecular Biology Reports Jan 2022A new species within the genus Alternaria was isolated from the leaf spot of Atractylodes ovata in the Mungyeong and Hwabuk-myeon districts of the Gyeongbuk province of...
BACKGROUND
A new species within the genus Alternaria was isolated from the leaf spot of Atractylodes ovata in the Mungyeong and Hwabuk-myeon districts of the Gyeongbuk province of Korea. The leaves showed disease symptoms such as circular or irregular leaf spots and brown to dark brown with gray spots at the center. The leaves also showed that concentric rings were surrounded with yellow halos.
METHODS AND RESULTS
Phylogenetic analysis was conducted using the sequence dataset of the internal transcribed spacer region and part of the glyceraldehyde-3-phosphate dehydrogenase. The RNA polymerase II second largest subunit, endopolygalacturonase, Alternaria major allergen gene, anonymous gene region, and translation elongation factor 1-alpha genes were used as well. Results showed that present fungal isolates were distinct from other species of the sect. Alternaria. Morphologically, the present isolates also differed from other members of the sect. Alternaria in their production of solitary conidia or conidial chains (two units) and conidial body features. Similarly, it exhibited moderate pathogenicity in the host plant.
CONCLUSIONS
This study described and illustrated A. koreana as a new species and the causal agent of the leaf-spot disease on A. ovata in Korea.
Topics: Alternaria; Atractylodes; DNA, Fungal; DNA, Intergenic; Fungal Proteins; Glyceraldehyde-3-Phosphate Dehydrogenases; Phylogeny; Plant Leaves; Republic of Korea
PubMed: 34739692
DOI: 10.1007/s11033-021-06887-9 -
Alternaria gansuense, a Plant Systematic Fungal Pathogen Producing Swainsonine in Vivo and in Vitro.Current Microbiology Jun 2023Astragalus adsurgens (A. adsurgens), which is considered a forage in China, grows widely in Eurasia and North America. However, Alternaria gansuense (A. gansuense)...
Astragalus adsurgens (A. adsurgens), which is considered a forage in China, grows widely in Eurasia and North America. However, Alternaria gansuense (A. gansuense) (synonym: Embellisia astragali) systematically infects A. adsurgens, producing swainsonine (SW), which poisons domesticated animals. In this study, we hypothesized that the A. gansuense SW-producing fungus is morphologically and molecularly related to the locoweed endophyte, Alternaria oxytropis (A. oxytropis), which systematically grows in host plants. Therefore, pure cultures of the fungi from diseased plants or endophytic interactions were collected from fields and assayed for SW via high-performance liquid chromatography linked to mass spectroscopy (HPLC-MS). The production of SW was also detected in A. adsurgens, A. oxytropis and diseased plants by assaying for the presence of the β-ketoacyl synthase (KS) gene, which is required for SW synthesis. Diseased A. adsurgens and pure cultures of A. gansuense have SW and the healthy-looking A. adsurgens plants also contained SW, probably because they were infected with A. gansuense. Therefore, A. adsurgens-infected A. gansuense are not safe for livestock consumption.
Topics: Animals; Swainsonine; Alternaria; Endophytes; China
PubMed: 37264252
DOI: 10.1007/s00284-023-03341-w -
FEMS Microbiology Reviews Jan 2013Host-selective toxins (HSTs) produced by fungal plant pathogens are generally low-molecular-weight secondary metabolites with a diverse range of structures that function... (Review)
Review
Host-selective toxins (HSTs) produced by fungal plant pathogens are generally low-molecular-weight secondary metabolites with a diverse range of structures that function as effectors controlling pathogenicity or virulence in certain plant-pathogen interactions. There are now seven known diseases caused by Alternaria alternata in which HSTs are responsible for fungal pathogenesis. The pathogens have been defined as pathotypes of A. alternata because of morphological similarity but pathological differences. Chemical structures of HSTs from six pathotypes have been determined. The role of A. alternata HSTs in pathogenesis has been studied extensively, and discovery of the release of HSTs from germinating conidia prior to penetration aids in understanding the early participation of HSTs to induce susceptibility of host cells by suppressing their defence reactions. Many attempts have been made to find the target sites of A. alternata HSTs, and four cellular components, plasma membrane, mitochondrion, chloroplast and a metabolically important enzyme, have been identified as the primary sites of each HST action, leading to elucidation of the molecular mechanisms of HST sensitivity in host plants. Studies of the molecular genetics of HST production have identified supernumerary chromosomes encoding HST gene clusters and have provided new insights into the evolution of A. alternata pathotypes.
Topics: Alternaria; Biological Evolution; Chromosomes, Fungal; Host Specificity; Models, Biological; Multigene Family; Mycotoxins; Plant Diseases; Plants; Spores, Fungal; Virulence
PubMed: 22846083
DOI: 10.1111/j.1574-6976.2012.00350.x -
Journal of Natural Products Mar 2023Altersteroids A-D (-), four new 9,11-secosteroid-derived γ-lactones, were isolated from cultures of the ascomycete fungus sp. Their structures were elucidated...
Altersteroids A-D (-), four new 9,11-secosteroid-derived γ-lactones, were isolated from cultures of the ascomycete fungus sp. Their structures were elucidated primarily by NMR experiments. The absolute configuration of was established by X-ray crystallographic analysis of its di--nitrobenzenesulfonate using Cu Kα radiation, whereas those for - were assigned by quantum-chemical calculations. Compounds - incorporate a γ-lactone moiety fused to the steroid D ring at C-13/C-14. Compound showed moderate cytotoxicity toward four tumor cell lines and induced an apoptotic process in A549 cells. Notably, compound showed equipotent activity against the cisplatin-sensitive MB49 and -resistant MB49 CisR cells, with an IC value of 12.7 μM.
Topics: Alternaria; Lactones; Molecular Structure; Ascomycota; Cell Line, Tumor; Secosteroids
PubMed: 36693727
DOI: 10.1021/acs.jnatprod.2c00975 -
International Archives of Allergy and... 2011Eosinophils are multifunctional leukocytes implicated in the pathogenesis of allergic diseases. An association between eosinophilic inflammation and infection or... (Review)
Review
Eosinophils are multifunctional leukocytes implicated in the pathogenesis of allergic diseases. An association between eosinophilic inflammation and infection or colonization by fungi has also been long recognized. However, the mechanisms underlying how eosinophils are activated and how they release proinflammatory and immunomodulatory mediators such as major basic protein (MBP) and eosinophil-derived neurotoxin remain largely unknown. We used a fungus, i.e. Alternaria, as a model microbe relevant to human asthma and chronic rhinosinusitis (CRS) to investigate the molecular mechanisms involved in the immune recognition of ubiquitous environmental allergens. Human eosinophils are activated by live Alternaria alternata organisms, release their granule proteins, and kill the fungi. Eosinophils, but not neutrophils, respond to secreted products from A. alternata. We found that eosinophils are equipped with innate cellular activation machinery that responds to an extracellular aspartate protease secreted by Alternaria. Aspartate protease activation of protease-activated receptor (PAR)-2 probably involves a novel mechanism different from that for serine protease activation of PAR-2. Thus, human eosinophils may recognize certain danger signals or virulence factors produced by fungi and provoke inflammatory responses against these organisms. Dysregulation of such an innate immune mechanism may be involved in the pathophysiology of certain human inflammatory diseases, including asthma and CRS.
Topics: Alternaria; Aspartic Acid Proteases; Eosinophils; Humans; Immunity, Innate; Receptor, PAR-2
PubMed: 21646807
DOI: 10.1159/000327498 -
Mycopathologia Sep 2005Here we report a case of cutaneous alternariosis in a 74-year-old man treated by corticotherapy for myasthenia, and presenting with papular, crusted lesions on the left... (Review)
Review
Here we report a case of cutaneous alternariosis in a 74-year-old man treated by corticotherapy for myasthenia, and presenting with papular, crusted lesions on the left elbow and the right knee. Histological examination of the biopsy specimens showed fungal hyphae associated with round-shaped cells which were highly suggestive of alternariosis. Mycological culture allowed the isolation of a dematiaceous fungus which was identified as a member of the Alternaria infectoria species-group. This was confirmed by PCR amplification and sequencing of the internal transcribed spacer domain of the gene encoding nuclear ribosomal DNA and of the mitochondrial small subunit ribosomal DNA domain. The fungus was therefore referred to the Scientific Institute of Public Health where it was identified as Alternaria infectoria, on the basis of its very small 1 or 2-celled conidia often arranged in long chains and presenting with very long secondary conidiophores. Corticotherapy was stopped and a local antifungal treatment with ketoconazole was initiated, allowing the stabilisation of the cutaneous lesions within 2 months.
Topics: Adult; Aged; Alternaria; DNA, Mitochondrial; DNA, Ribosomal Spacer; Dermatomycoses; Female; Humans; Knee; Male; Middle Aged; Molecular Sequence Data; RNA, Ribosomal, 5.8S; Sequence Analysis, DNA
PubMed: 16170606
DOI: 10.1007/s11046-005-5259-5 -
Eukaryotic Cell Apr 2015Alternaria species are mainly saprophytic fungi, but some are plant pathogens. Seven pathotypes of Alternaria alternata use secondary metabolites of host-specific toxins... (Review)
Review
Alternaria species are mainly saprophytic fungi, but some are plant pathogens. Seven pathotypes of Alternaria alternata use secondary metabolites of host-specific toxins as pathogenicity factors. These toxins kill host cells prior to colonization. Genes associated with toxin synthesis reside on conditionally dispensable chromosomes, supporting the notion that pathogenicity might have been acquired several times by A. alternata. Alternaria brassicicola, however, seems to employ a different mechanism. Evidence on the use of host-specific toxins as pathogenicity factors remains tenuous, even after a diligent search aided by full-genome sequencing and efficient reverse-genetics approaches. Similarly, no individual genes encoding lipases or cell wall-degrading enzymes have been identified as strong virulence factors, although these enzymes have been considered important for fungal pathogenesis. This review describes our current understanding of toxins, lipases, and cell wall-degrading enzymes and their roles in the pathogenesis of A. brassicicola compared to those of other pathogenic fungi. It also describes a set of genes that affect pathogenesis in A. brassicicola. They are involved in various cellular functions that are likely important in most organisms and probably indirectly associated with pathogenesis. Deletion or disruption of these genes results in weakly virulent strains that appear to be sensitive to the defense mechanisms of host plants. Finally, this review discusses the implications of a recent discovery of three important transcription factors associated with pathogenesis and the putative downstream genes that they regulate.
Topics: Alternaria; Arabidopsis; Fungal Proteins; Gene Expression Regulation, Fungal; Mycotoxins; Plant Cells; Plant Diseases; Reverse Genetics; Transcription Factors; Virulence Factors
PubMed: 25681268
DOI: 10.1128/EC.00226-14 -
BMC Microbiology Feb 2019The indolizidine alkaloid-swainsonine is produced by an endophytic fungus Alternaria oxytropis, which was isolated from locoweeds. Swainsonine has many biological...
BACKGROUND
The indolizidine alkaloid-swainsonine is produced by an endophytic fungus Alternaria oxytropis, which was isolated from locoweeds. Swainsonine has many biological activities such as anti-tumorigenic, anti-viral and bacteriostatic. However, the full complement of metabolites produced by Alternaria oxytropis is not known. This study is a chemical analysis of Alternaria oxytropis metabolites, which not only unravels the potential compounds from the fermentation broth but also in which solvent are they extracted, facilitating industrial application.
RESULTS
Alternaria oxytropis isolated from Oxytropis gansuensis was cultured in Czapek's medium for 30d to collect the fermentation broth. The fermentation broth is treated with methanol and then evaporated to dryness to obtain a concentrate of the fermentation broth. The concentrate is added with water for the subsequent fractional extraction with petroleum ether, chloroform, ethyl acetate and n-butanol. Different fractions of the extract were eluted by wet packing and dry loading. The obtained eluate was combined by TLC to detect the same fraction, and then characterized by GC-MS and LC-MS. The results of GC-MS showed that 105 different compounds existed in the petroleum ether, chloroform, and ethyl acetate phases of Alternaria oxytropis fermentation broth. Moreover, the results of LC-MS indicated that the fermentation broth of Alternaria oxytropis contained five alkaloids, 2-hydroxy-indolizidine, retronecine, lentiginosine, swainsonine and swainsonine N-oxide.
CONCLUSIONS
In addition to swainsonine and swainsonine N-oxide, 2-hydroxy-indolizidine, retronecine and lentiginosine were identified as the secondary metabolites of Alternaria oxytropis. Other compounds were also detected including 5,6-dihydroergosterol, eburicol, lanosterol, and L-phenylalanyl-L-proline lactam, which have potential applications as drugs.
Topics: Alkaloids; Alternaria; Astragalus Plant; Chromatography, Liquid; Culture Media; Fermentation; Gas Chromatography-Mass Spectrometry; Industrial Microbiology; Metabolic Networks and Pathways; Tandem Mass Spectrometry
PubMed: 30744547
DOI: 10.1186/s12866-019-1408-8 -
Plant Disease Apr 2021The fungal genus consists of highly diverse species. They can be isolated readily from soil, water, and many plants, and even from animals and humans. is a...
The fungal genus consists of highly diverse species. They can be isolated readily from soil, water, and many plants, and even from animals and humans. is a small-spored species of section . It has been reported as a pathogen, an endophyte, and a saprophyte, and can also be found in indoor air. It causes cumin blight, a destructive disease on cumin (), and also causes other serious diseases, such as pumpkin seed rot, date palm leaf spot, wheat leaf spot, and gray spot of . In this study, we sequenced and assembled the first genome of isolate CBS 107.38. The draft genome can be used as a reference for the further study of related pathogens and comparative genomics of species.
Topics: Alternaria; Apiaceae; Cuminum; Genomics
PubMed: 32990522
DOI: 10.1094/PDIS-02-20-0224-A -
International Journal of Food... Mar 2019Black point is one of the most important wheat disease and its incidence is increasing worldwide due to climate change too. Among the fungal genera that can cause black...
Black point is one of the most important wheat disease and its incidence is increasing worldwide due to climate change too. Among the fungal genera that can cause black point, Alternaria is one of the predominant genus, often associated with mycotoxin contamination. The correct identification is the baseline for prevention and control of the disease. Taxonomy of the genus Alternaria is not completely clear yet, since its species can be differentiated for few morphological traits and, in some cases, also molecular phylogeny is not very effective in establishing species boundaries. In this study, one-hundred sixty-four strains, isolated from wheat kernels affected by black point sampled worldwide, were analyzed in order to assess their identity. Sequences of elongation factor, β-tubulin, glyceraldehyde-3-phosphate dehydrogenase and allergen alt-a1 genes were used to identify the variability of this population and their phylogenetic relationships. Isolates were grouped in two main clades: the Alternaria section, including A. alternata, A. tenuissima and A. arborescens species, and the Infectoriae section, that includes the two species A. infectoria and A. triticina. Comparison of isolates according with their area of isolation did not show a correlation between phylogeny and geographic origin. Indeed, the isolates grouped on the base of only their phylogenetic relationship. Due to the data arisen by our study, we strongly recommend a multilocus sequence approach to define Alternaria species, based on common genes and procedures to be unanimously shared by scientific community dealing with Alternaria genus. Moreover, we suggest that A. alternata, A. tenuissima, A. turkisafria and A. limoniasperae species would be merged in the defined species A. alternata. Finally we recommend to consider a taxonomic re-evaluation of the Infectoriae section that, for the morphology, sexuality, genetic and mycotoxin profile of the species included, could be defined as different fungal genus from Alternaria.
Topics: Alternaria; DNA, Fungal; Multilocus Sequence Typing; Mycotoxins; Phenotype; Phylogeny; Phylogeography; Plant Diseases; Sequence Alignment; Sequence Analysis, DNA; Triticum
PubMed: 30634069
DOI: 10.1016/j.ijfoodmicro.2019.01.001