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Journal of Fungi (Basel, Switzerland) Jul 2022Amplicon sequencing is a powerful tool for analyzing the fungal composition inside plants, whereas its application for the identification of etiology for plant diseases...
Amplicon sequencing is a powerful tool for analyzing the fungal composition inside plants, whereas its application for the identification of etiology for plant diseases remains undetermined. Here, we utilize this strategy to clarify the etiology responsible for tea leaf brown-black spot disease (LBSD), a noticeable disease infecting tea plants etiology that remains controversial. Based on the ITS-based amplicon sequencing analysis, species were identified as separate from spp. and sp., which are concluded as the etiological agents. This was further confirmed by the fungal isolation and their specific pathogenicity on diverse tea varieties. Based on the morphologies and phylogenetic analysis constructed with multi-loci (ITS, LSU, and ), two novel species-tentatively named and as reference to their host plants-were proposed and characterized. Here, we present an integrated approach of ITS-based amplicon sequencing in combination with fungal isolation and fulfillment of Koch's postulates for etiological identification of tea plant disease, revealing new etiology for LBSD. This contributes useful information for further etiological identification of plant disease based on amplicon sequencing, as well as understanding, prevention, and management of this economically important disease.
PubMed: 35893150
DOI: 10.3390/jof8080782 -
Journal of Fungi (Basel, Switzerland) Dec 2023In Colombia, plantings with the oil palm hybrid between × , known as O × G hybrid, have increased due to its tolerance to bud rot. Despite this, different degrees of...
In Colombia, plantings with the oil palm hybrid between × , known as O × G hybrid, have increased due to its tolerance to bud rot. Despite this, different degrees of foliar necrosis, chlorosis, and leaf blight have been reported in some cultivars; therefore, this work aimed to diagnose this problem. We visited plantation plots with palms exhibiting the mentioned symptoms and collected 21 samples of affected tissues in different disease states. The affected tissues were examined and seeded in a culture medium. Pathogenicity tests were performed and the isolates were characterized by culture and morphological and molecular features. , , , and 25 -like fungi were isolated from the foliar lesions. In the pathogenicity tests, the symptoms observed in the field were reproduced with MFTU01-1, MFTU12, and MFTU21 isolates, which were identified at the species level through a sequence analysis of three genes (, , and ) as with an identical level of 99% based on the results of BLAST and phylogenetic tree analyses. The remaining 22 -like non-pathogenic isolates were identified as species of and . The direct association of with the disease was confirmed via molecular detection in affected tissues in 15 of 21 samples collected for this evaluation. This is the first report of as the causal agent of foliar lesions in O × G hybrid oil palm in Colombia.
PubMed: 38248934
DOI: 10.3390/jof10010024 -
Frontiers in Microbiology 2022In the tobacco phyllosphere, some of the microbes may have detrimental effects on plant health, while many may be neutral or even beneficial. Some cannot be cultivated,...
In the tobacco phyllosphere, some of the microbes may have detrimental effects on plant health, while many may be neutral or even beneficial. Some cannot be cultivated, so culture-independent methods are needed to explore microbial diversity. In this study, both metagenetic analysis and traditional culture-dependent methods were used on asymptomatic healthy leaves and symptomatic diseased leaves of tobacco plants. In the culture-independent analysis, asymptomatic leaves had higher microbial diversity and richness than symptomatic leaves. Both asymptomatic and symptomatic leaves contained several potentially pathogenic bacterial and fungal genera. The putative bacterial pathogens, such as species of , , or , and putative fungal pathogens, such as species of , , , , , and , had a higher relative abundance in symptomatic leaves than asymptomatic leaves. FUNGuild analysis indicated that the foliar fungal community also included endophytes, saprotrophs, epiphytes, parasites, and endosymbionts. PICRUSt analysis showed that the dominant functions of the bacterial community in a symptomatic leaf were cellular processes and environmental information processing. In the other five foliar samples, the dominant functions of the bacterial community were genetic information processing, metabolism, and organismal systems. In the traditional culture-dependent method, 47 fungal strains were isolated from 60 symptomatic tobacco leaf fragments bearing leaf spots. Among them, 21 strains of (29%), (14%), (14%), (10%), (10%), (10%), (5%), (5%), and (5%) all fulfilled Koch's postulates and were found to cause disease on detached tobacco leaves in artificial inoculation tests. Symptoms on detached leaves caused by three strains of in artificial inoculation tests were similar to the original disease symptoms in the tobacco field. This study showed that the combined application of culture-dependent and independent methods could give comprehensive insights into microbial composition that each method alone did not reveal.
PubMed: 35572673
DOI: 10.3389/fmicb.2022.843389 -
TheScientificWorldJournal 2022This study was conducted to isolate and identify the endophytic fungi from the bark and leaves of the plant and investigate the pharmacological activities of endophytic...
This study was conducted to isolate and identify the endophytic fungi from the bark and leaves of the plant and investigate the pharmacological activities of endophytic fungi along with plant parts. After isolation, endophytic fungi were identified based on morphological characteristics and molecular identification. Antimicrobial, antioxidant, and cytotoxic activities were studied by a disc diffusion method, free radical scavenging DPPH assay, and brine shrimp lethality bioassay, respectively. A total of eight endophytic fungi were isolated and identified up to the genus level based on morphological characteristics and confirmed by molecular identification techniques. Among the eight isolates, three isolates were identified as sp. (SCBE-2, SCBE-7, and SCLE-9), while the rest of the isolates belonged to sp. (SCBE-1), sp. (SCBE-3), sp. (SCBE-4), sp. (SCLE-7), and sp. (SCLE-8). The presence of flavonoids, anthraquinones, coumarins, and isocoumarins was assumed by the preliminary screening of the fungal and plant extracts by a thin-layer chromatographic technique under UV light. Fungal extracts of sp. sp. were found sensitive to all test bacteria, but only extracts from the leaf and bark showed significant antifungal activity along with their antimicrobial activity. sp. The fungal extract showed the highest free radical scavenging activity (2.43 g/mL) near that of ascorbic acid (2.42 g/mL). Some fungal extracts showed cytotoxic activity that, in general, suggests their probable abundance of biological metabolites. This is the first approach to investigate the endophytic fungi of Linn. in Bangladesh, to find the pharmacological potential of endophytes, and to explore novel compounds from those endophytes.
Topics: Syzygium; Fungi; Endophytes; Anti-Infective Agents; Free Radicals
PubMed: 36393829
DOI: 10.1155/2022/9529665 -
Current Medical Mycology Sep 2023Onychomycosis caused by dematiaceous fungi is rarely reported and the identification is also quite tricky due to poor sporulation. Recent emergence of dematiaceous fungi...
BACKGROUND AND PURPOSE
Onychomycosis caused by dematiaceous fungi is rarely reported and the identification is also quite tricky due to poor sporulation. Recent emergence of dematiaceous fungi as a major cause of onychomycosis is a matter of concern in the field of mycology. Therefore, this study aimed to understand the dematiaceous fungi as a possible cause of onychomycosis, especially among agricultural workers. In addition, the evaluation of the antifungal susceptibility patterns led to the idea of an accurate drug that will help to treat and prevent antifungal resistance.
MATERIALS AND METHODS
The standard procedure was followed for direct microscopic examination and fungi isolation. Furthermore, antifungal susceptibility testing was conducted in accordance with the Clinical and Laboratory Standards Institute M-38-A2 protocol.
RESULTS
Both potassium hydroxide and fungal positivity were found in 275 out of 356 suspected cases, 52%, 4.3%, 28.7%, and 14.9% of which were non-dermatophytic molds (NDMs), yeast, dermatophytes, and sterile hyphae, respectively. Among NDMs (52%, n=143), 45.5% (n=65) were hyaline hyphomycetes and 54.5% (n=78) were dematiaceous hyphomycetes. Among dematiaceous fungi, spp. and spp. were the commonly isolated ones. Additionally, azoles, amphotericin-B, and anidulafungin showed excellent antifungal activity against tested isolates.
CONCLUSION
Dematiaceous fungi are now becoming a potential cause of onychomycosis. A more detailed study is needed on the identification of these emerging isolates and the mode of action of antifungal drugs for a better treatment strategy.
PubMed: 38361959
DOI: 10.22034/cmm.2023.345077.1428 -
Journal of Fungi (Basel, Switzerland) Nov 2022Pepper leaf spot is a common disease of . When it is serious, it directly affects the growth of , making the plant unable to blossom and bear fruit, which seriously...
Pepper leaf spot is a common disease of . When it is serious, it directly affects the growth of , making the plant unable to blossom and bear fruit, which seriously restricts the development of the industry. Therefore, the pathogenic mechanism of leaf spots should be explored to provide a basis for a comprehensive understanding of the disease. Using liquid chromatography-mass spectrometry (LC-MS) technology combined with the data-dependent acquisition, the full spectrum analysis of pathogen mycelium samples was carried out. Partial least squares discriminant analysis (PLS-DA) was used to reveal the differences in metabolic patterns among different groups. Hierarchical clustering analysis (HCA) and PLS-DA were used to reveal the relationship between samples and metabolites, which reflected the metabolomics changes of in the logarithmic growth phase of mycelia, the stable growth phase of mycelia, the massive spore stage, the induction culture conditions of PDA and leaves, and the possible pathogenic substances were selected for pathogenicity detection. PLS-DA had a strong predictive ability, indicating a clear analysis trend between different groups. The results of the metabolomics analysis showed that the differential metabolites of pathogenic bacteria were abundant at different stages and under different medium conditions, and the content of metabolites changed significantly. There were 3922 differential metabolites in nine groups under positive and negative ion modes, including lipids and lipid molecules, organic acids and their derivatives, organic heterocyclic compounds, organic oxygen compounds, carbohydrate polyketides, nucleosides, nucleotides, and analogs. The results of the pathogenicity test showed that the leaves treated with 3,5-dimethoxy benzoic acid, -(5-adenosy)-l-homocysteine, 2-(1-indol-3-yl) acetic acid, l-glutamic acid, and 2-(2-acetyl-3,5-dihydroxy phenyl) acetic acid showed different degrees of yellowish-brown lesions. This indicated that these substances may be related to the pathogenicity of , and the incidence was more serious when treated with 3,5-dimethoxybenzoic acid and -(5-adenosy)- l -homocysteine. This study provides a basis for further analysis of differential metabolites and provides a theoretical reference for the prevention and treatment of leaf spot.
PubMed: 36422029
DOI: 10.3390/jof8111208 -
PloS One 2021The eye is host to myriad bacterial, fungal, and viral organisms that likely influence ocular surface physiology in normal and diseased states. The ocular surface...
The eye is host to myriad bacterial, fungal, and viral organisms that likely influence ocular surface physiology in normal and diseased states. The ocular surface mycobiota of horses has not yet been described using NGS techniques. This study aimed to characterize the ocular surface fungal microbiota (mycobiota) in healthy horses in 2 environmental conditions (stalled versus pasture). Conjunctival swabs of both eyes were obtained from 7 adult stallions stabled in an open-air pavilion and 5 adult mares living on pasture. Genomic DNA was extracted from ocular surface swabs and sequenced using primers that target the Internal Transcribed Spacer 1 (ITS1) region of the fungal genome on an Illumina platform. Sequences were processed using Quantitative Insights Into Molecular Ecology (QIIME 2.0) and taxonomy assigned with the Findley et al. 2013 ITS1 database. The most abundant genera identified were Leptosphaerulina (22.7%), unclassified Pleosporaceae (17.3%), Cladosporium (16.2%), Alternaria (9.8%), unclassified Pleosporales (4.4%), unclassified Montagnulaceae (2.9%), Fusarium (2.5%), and Pestalotiopsis (1.4%). Fungal community composition (Jaccard, R = 0.460, p = 0.001) and structure (Bray-Curtis, R = 0.811, p = 0.001) were significantly different between pastured mares and stabled stallions. The ocular surface of pastured mares had significantly increased fungal species richness and diversity compared to stabled stallions (Shannon p = 0.0224, Chao1 p = 0.0118, Observed OTUs p = 0.0241). Relative abundances of Aspergillus (p = 0.005) and Alternaria spp. (p = 0.002) were significantly increased in the mycobiota of pastured mares. This is the first report to describe the mycobiota of the equine ocular surface. Environmental factors such as housing influence the composition, structure, and richness of the equine ocular surface mycobiota.
Topics: Alternaria; Animals; Aspergillus; Cladosporium; Eye; Female; Fusarium; Horses; Male; Pestalotiopsis
PubMed: 33539431
DOI: 10.1371/journal.pone.0246537 -
Plant Disease Jun 2023(Burkill) F. H. Chen ex C. Y. Wu & K.M. Feng is a Chinese herbal medicinal plant for treating diseases of the central nervous system and cardiovascular system, widely...
(Burkill) F. H. Chen ex C. Y. Wu & K.M. Feng is a Chinese herbal medicinal plant for treating diseases of the central nervous system and cardiovascular system, widely used as a medicine and health-care product. In May 2022, leaf blight disease was found on leaves of 1-year-old in the plantings (27.904°N, 112.918°E) of Xiangtan City (Hunan) with an area of 10 m. Over 400 plants were investigated, up to 25% of the plants were symptomatic. From the margin of the leaf, the initial symptoms of water-soaked chlorosis and following dry yellow with slight shrinkage appeared. Later, leaf shrinkage became serious and chlorosis enlarged gradually, leading to leaf death and abscission. To identify the causal agent, 20 leaf lesions (4 mm) collected from 20 individual 1-year-old plants were sterilized with 75% ethanol for 10 s, 5% NaOCl for 10 s, rinsed in sterilized water three times, placed on potato dextrose agar (PDA) with lactic acid (0.125%) for inhibition the growth of bacteria, and incubated at 28°C for 7 days (Fang, 1998). Five isolates were obtained from 20 leaf lesions of different plants with the isolation rate of 25% and purified by single sporing, which have similar colony and conidia morphology characteristics. One isolate PB2-a was selected randomly for further identification. Colonies of PB2-a on PDA were white with cottony mycelium, developing concentric circles (top view) or light yellow (back view). Conidia (23.1 ± 2.1 × 5.7 ± 0.8 µm, n=30)were fusiform, straight or slightly curved and contained conic basal cell, three light brown median cells and hyaline conic apical cell with appendages. The rDNA internal transcribed spacer (ITS), the translation elongation factor 1-alpha (), and the β-tubulin (TUB2) genes were amplified from genomic DNA of PB2-a using primers ITS4/ITS5 (White et al. 1990), EF1-526F/EF1-1567R (Maharachchikumbura et al. 2012), and Bt2a/Bt2b (Glass and Donaldson, 1995; O'Donnell and Cigelnik, 1997), respectively. BLAST search of sequenced ITS (OP615100), (OP681464) and TUB2 (OP681465) exhibited > 99% identity with the type strain of OP068 (JQ845947, JQ845946 and JQ845945). Phylogenetic tree of the concatenated sequences was constructed based on the maximum-likelihood method using MEGA-X. Isolate PB2-a was identified as based on morphological and molecular data (Maharachchikumbura et al. 2011; Qi et al. 2022). PB2-a was tested for pathogenicity three times to confirm Koch's postulates. Twenty healthy leaves on 20 1-year-old plants were punctured with sterile needles and inoculated with 50 µl of conidial suspension (1×10 conidia/ml). The controls were inoculated with sterile water. All plants were placed in a greenhouse at 25°C under 80% relative humidity. After 7 days, all inoculated leaves developed leaf blight symptoms identical to those described above, whereas the control plants kept healthy. were reisolated from infected leaves, and identical to those of the originals based on the colony characteristics and the sequenced data of ITS, and TUB2. was reported as a pathogen of leaf blight on (Xu et al. 2022). To our knowledge, this is the first report of causing leaf blight on in Hunan, China. Leaf blight is one of the destructive diseases in production, identification of the pathogen will be useful to develop effective disease management and protect , a medical plant with economic value.
PubMed: 37294156
DOI: 10.1094/PDIS-04-23-0681-PDN -
Pathogens (Basel, Switzerland) Nov 2023The main pathogens affecting the carob () tree in the Mediterranean basin are described in this overview. The most widespread diseases periodically occurring in carob... (Review)
Review
The main pathogens affecting the carob () tree in the Mediterranean basin are described in this overview. The most widespread diseases periodically occurring in carob orchards are powdery mildew () and cercospora leaf spot (). The causal agents of "black leaf spots" (e.g., , and spp.) are responsible for symptoms similar to those previously mentioned for foliar diseases, but are reported in carob orchards at a negligible frequency. Likewise, canker and branch diebacks caused by fungal species belonging to Botryosphaeriaceae are almost never recorded. Among the rots of wood tissues that may compromise old carob specimens, "brown cubical rot" caused by is the most widespread and recurrent issue; this pathogen is also well-known for producing edible fruit bodies that are appreciated for pharmaceutical and industrial purposes. On the other hand, "white rots" caused by and species are less common and reported for the first time in this review. Gall-like protuberances on twigs of uncertain aetiology or tumors on branches associated with are described, although these symptoms are seldom detected, as they are also observed for necrotic leaf spots caused by pv. . A worldwide list of pathogens not yet recorded but at high risk of potential introduction in Italian carob-producing areas is also provided. Finally, concerns related to new phytopathogenic fungi vectored by the invasive ambrosia beetle are addressed. All the described pathogens could become limiting factors for carob production in the near future, because they could be favored by high-density orchards, the increasing global network of trade exchanges, and the high frequency at which extreme events related to climate change occur globally. Thus, symptoms and signs, causal agents, epidemiology, and, whenever applicable, recommendations for disease prevention and management are provided in this review.
PubMed: 38003821
DOI: 10.3390/pathogens12111357 -
Journal of Fungi (Basel, Switzerland) Dec 2021Melanins are the common fungal pigment, which contribute to stress resistance and pathogenesis. However, few studies have explored the regulation mechanism of its...
Melanins are the common fungal pigment, which contribute to stress resistance and pathogenesis. However, few studies have explored the regulation mechanism of its synthesis in filamentous fungi. In this study, we identified two transcription factors, Pmr1 and Pmr2, in the filamentous fungus . Computational and phylogenetic analyses revealed that Pmr1 and Pmr2 were located in the gene cluster for melanin biosynthesis. The targeted deletion mutant strain displayed defects in biosynthesis of conidia pigment and morphological integrity. The deletion of resulted in reduced conidia pigment, but the mycelial morphology had little change. Moreover, produced decreased conidia. RT-qPCR data revealed that expression levels of genes in the melanin biosynthesis gene cluster were downregulated from the loss of Pmr1 and Pmr2. Interestingly, the yield of secondary metabolites in the mutant strains and increased, comparing with the wild type, and additionally, Pmr1 played a larger regulatory role in secondary metabolism. Taken together, our results revealed the crucial roles of the transcription factors Pmr1 and Pmr2 in melanin synthesis, asexual development and secondary metabolism in the filamentous fungus .
PubMed: 35049978
DOI: 10.3390/jof8010038