-
PloS One 2016Alternaria brown spot is one of the most important diseases of tangerines and their hybrids worldwide. Recently, outbreaks in Mediterranean areas related to susceptible...
Alternaria brown spot is one of the most important diseases of tangerines and their hybrids worldwide. Recently, outbreaks in Mediterranean areas related to susceptible cultivars, refocused attention on the disease. Twenty representatives were selected from a collection of 180 isolates of Alternaria spp. from citrus leaves and fruit. They were characterized along with reference strains of Alternaria spp. Micro- and macroscopic characteristics separated most Alternaria isolates into six morphotypes referable to A. alternata (5) and A. arborescens (1). Phylogenetic analyses, based on endopolygalacturonase (endopg) and internal transcribed spacer (ITS), confirmed this finding. Moreover, a five-gene phylogeny including two anonymous genomics regions (OPA 1-3 and OPA 2-1), and the beta-tubulin gene (ß-tub), produced a further clustering of A. alternata into three clades. This analysis suggested the existence of intra-species molecular variability. Investigated isolates showed different levels of virulence on leaves and fruit. In particular, the pathogenicity on fruit seemed to be correlated with the tissue of isolation and the clade. The toxigenic behavior of Alternaria isolates was also investigated, with tenuazonic acid (TeA) being the most abundant mycotoxin (0.2-20 mg/L). Isolates also synthesized the mycotoxins alternariol (AOH), its derivate alternariol monomethyl ether (AME), and altenuene (ALT), although to a lesser extent. AME production significantly varied among the six morphotypes. The expression of pksJ/pksH, biosynthetic genes of AOH/AME, was not correlated with actual toxin production, but it was significantly different between the two genotypes and among the four clades. Finally, ten isolates proved to express the biosynthetic genes of ACTT1 phytotoxin, and thus to be included in the Alternaria pathotype tangerine. A significant correlation between pathogenicity on leaves and ACTT1 gene expression was recorded. The latter was significantly dependent on geographical origin. The widespread occurrence of Alternaria spp. on citrus fruit and their ability to produce mycotoxins might represent a serious concern for producers and consumers.
Topics: Alternaria; Citrus; Mediterranean Region; Plant Diseases
PubMed: 27636202
DOI: 10.1371/journal.pone.0163255 -
FEMS Microbiology Letters May 2021Swainsonine, an indolizidine alkaloid, is a promising anti-tumorigenic compound. Biological production of swainsonine was prospective, but the low swainsonine yield of...
Swainsonine, an indolizidine alkaloid, is a promising anti-tumorigenic compound. Biological production of swainsonine was prospective, but the low swainsonine yield of wild type Alternaria oxytropis limited its production on a large scale. In present work, a stable A. oxytropis mutant UO1 with swanisonine yield of 14.84% higher than the wild-type strain was successfully obtained after heavy-ion irradiation. The A. oxytropis mutant UO1 and original wild-type strain were futher evaluated for SW concentrations under different factors. Results showed that the optimum culture temperature was 25°C. The optimum initial medium pH was 6.5 and the optimum inoculum size was 2 mL per 200 mL. Addition of the biosynthetic precursor L-pipecolic acids and L-lysine appropriately could increase the SW synthesis. These findings provided a theoretical basis and scientific data for the industrial production of swainsonine.
Topics: Alternaria; Culture Media; Heavy Ions; Industrial Microbiology; Mutagenesis; Swainsonine
PubMed: 33942869
DOI: 10.1093/femsle/fnab047 -
Plant Disease Mar 2022
Topics: Alternaria; Capsicum; Pakistan; Plant Diseases
PubMed: 34260285
DOI: 10.1094/PDIS-12-20-2706-PDN -
Plant Disease Jan 2021Watermelon is an economically important crop in China and is commonly affected by -like leaf blight that can result in significant economic losses. In this study, 830...
Watermelon is an economically important crop in China and is commonly affected by -like leaf blight that can result in significant economic losses. In this study, 830 isolates, recovered from symptomatic watermelon leaves, were identified based on morphological traits, pathogenicity, and multilocus sequence analyses of glyceraldehyde-3-phosphate dehydrogenase (), histone 3 (), the internal transcribed spacer of ribosomal DNA (rDNA ITS), and the RNA polymerase II second largest subunit (). Watermelon isolates grouped to five species and one unclassified species. They were , , , , , and sp. Notably, was the most prevalent (73.5%) of the six isolated species, followed by (25.0%), (1.1%), sp. (0.2%), (0.1%), and (0.1%). Pathogenicity tests demonstrated that all six species could produce brown necrotic lesions on detached leaves of watermelon. The average disease incidence (75.1%) and average disease index (60.8) of watermelon resulting from inoculation of leaves with were significantly higher than levels resulting from (52.9% and 37.2) and (47.5% and 30.8). Inoculation with sp. resulted in a disease incidence (70.0%) and disease index (51.5), which were lower than those of . The disease incidence and disease index in watermelon leaves inoculated with the one isolate of and the one isolate of present in the inoculated leaves were 28.9% and 16.4, and 48.9% and 31.4, respectively. Results of the study indicate that species associated with watermelon leaf blight in China are more diverse than that has been previously reported. This is the first report globally of , , and an unclassified species as causal agents of leaf blight on watermelon.
Topics: Alternaria; China; Citrullus; Multilocus Sequence Typing; Phylogeny
PubMed: 33170772
DOI: 10.1094/PDIS-01-20-0130-RE -
Chemistry & Biodiversity Dec 2015The microbial transformation of 14-anhydrodigoxigenin (1) by Alternaria alternata CGMCC 3.577 led to the production of seven new metabolites, 2-8. Their structures were...
The microbial transformation of 14-anhydrodigoxigenin (1) by Alternaria alternata CGMCC 3.577 led to the production of seven new metabolites, 2-8. Their structures were determined by extensive spectroscopic (CD, IR, 1D- and 2D-NMR, and HR-ESI-MS) data analyses. The reactions in the bioprocess exhibited diversity, including specific oxidation, hydroxylation, reduction, epoxidation, and dehydration. In addition, a hypothetical biocatalytic pathway is proposed.
Topics: Activation, Metabolic; Alternaria; Digoxigenin; Hydroxylation; Magnetic Resonance Spectroscopy; Molecular Structure
PubMed: 26663840
DOI: 10.1002/cbdv.201500024 -
International Journal of Food... Mar 2018Twenty-four Alternaria strains were isolated from barley grain samples. These strains were screened for the production of mycotoxins on rice medium using thin layer...
Twenty-four Alternaria strains were isolated from barley grain samples. These strains were screened for the production of mycotoxins on rice medium using thin layer chromatography. All 24 strains produced at least one of the five mycotoxins (ALT, AOH, ATX-I, AME, and TeA). Three representative strains, namely EML-BLDF1-4, EML-BLDF1-14, and EML-BLDF1-18, were further analyzed using a new LC-MS/MS-based mycotoxin quantification method. This method was used to detect and quantify Alternaria mycotoxins. We used positive ion electrospray mass spectrometry with multiple reaction mode (MRM) for the simultaneous quantification of various Alternaria mycotoxins produced by these strains. Five Alternaria toxins (ALT, ATX-I, AOH, AME, and TeA) were detected and quantified. Sample preparation included methanol extraction, concentration, and injection into LC-MS/MS. Limit of detection ranged from 0.13 to 4μg/mL and limit of quantification ranged from 0.25 to 8μg/mL.
Topics: Alternaria; Chromatography, Liquid; Chromatography, Thin Layer; Edible Grain; Food Contamination; Hordeum; Lactones; Mycotoxins; Republic of Korea; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry
PubMed: 29328967
DOI: 10.1016/j.ijfoodmicro.2018.01.003 -
Journal of Asian Natural Products... Jun 2023Alternarialone A (), one new curvularin derivative, and two known compounds ( and ) were isolated from the crude extract of the mangrove-derived fungus . Their...
Alternarialone A (), one new curvularin derivative, and two known compounds ( and ) were isolated from the crude extract of the mangrove-derived fungus . Their structures were elucidated by comprehensive spectroscopic analyses, including MS and NMR spectroscopic data. The absolute configuration of was assigned by C NMR calculations and a comparison of electronic circular dichroism (ECD) spectra. All compounds were evaluated for their antibacterial activities against . Compounds and showed antibacterial activities against G27 with MIC values of 8 and 16 µg/ml, respectively, while compound also displayed antibacterial activity against BHKS159 with the MIC value of 16 µg/ml.
Topics: Alternaria; Zearalenone; Anti-Bacterial Agents; Microbial Sensitivity Tests; Molecular Structure
PubMed: 36048769
DOI: 10.1080/10286020.2022.2117168 -
BMC Plant Biology Sep 2022Alternaria solani is a typical necrotrophic pathogen that can cause severe early blight on Solanaceae crops and cause ring disease on plant leaves. Phytopathogens...
BACKGROUND
Alternaria solani is a typical necrotrophic pathogen that can cause severe early blight on Solanaceae crops and cause ring disease on plant leaves. Phytopathogens produce secretory effectors that regulate the host immune response and promote pathogenic infection. Effector proteins, as specialized secretions of host-infecting pathogens, play important roles in disrupting host defense systems. At present, the role of the effector secreted by A. solani during infection remains unclear. We report the identification and characterization of AsCEP112, an effector required for A. solani virulence.
RESULT
The AsCEP112 gene was screened from the transcriptome and genome of A. solani on the basis of typical effector signatures. Fluorescence quantification and transient expression analysis showed that the expression level of AsCEP112 continued to increase during infection. The protein localized to the cell membrane of Nicotiana benthamiana and regulated senescence-related genes, resulting in the chlorosis of N. benthamiana and tomato leaves. Moreover, comparative analysis of AsCEP112 mutant obtained by homologous recombination with wild-type and revertant strains indicated that AsCEP112 gene played an active role in regulating melanin formation and penetration in the pathogen. Deletion of AsCEP112 also reduced the pathogenicity of HWC-168.
CONCLUSION
Our findings demonstrate that AsCEP112 was an important effector protein that targeted host cell membranes. AsCEP112 regulateed host senescence-related genes to control host leaf senescence and chlorosis, and contribute to pathogen virulence.
Topics: Alternaria; Anemia, Hypochromic; Melanins; Plant Diseases
PubMed: 36171557
DOI: 10.1186/s12870-022-03845-w -
Methods in Molecular Biology (Clifton,... 2017Real-time polymerase chain reaction (PCR) is a molecular biology technique based on the detection of the fluorescence produced by a reporter molecule, which increases as...
Real-time polymerase chain reaction (PCR) is a molecular biology technique based on the detection of the fluorescence produced by a reporter molecule, which increases as the reaction proceeds proportionally to the accumulation of the PCR product within each amplification cycle. The fluorescent reporter molecules include dyes that bind to the double-stranded DNA (i.e., SYBR Green) or sequence-specific probes (i.e., Molecular Beacons or TaqMan Probes). Real-time PCR provides a tool for accurate and sensitive quantification of target fungal DNA. Here, we describe a TaqMan real-time PCR method for specific detection and quantification of Alternaria spp. The method uses Alternaria-specific primers and probe, targeting the internal transcribed spacer regions ITS1 and ITS2 of the rRNA gene, and a positive amplification control based on 18S rRNA gene.
Topics: Alternaria; Conserved Sequence; DNA, Intergenic; Evolution, Molecular; Genes, Fungal; Real-Time Polymerase Chain Reaction
PubMed: 27924533
DOI: 10.1007/978-1-4939-6707-0_6 -
Toxins Apr 2020Black point is a fungal disease of wheat, mainly associated with mycotoxigenic species. Affected wheat kernels are characterized by dark brown discolouration of the...
Black point is a fungal disease of wheat, mainly associated with mycotoxigenic species. Affected wheat kernels are characterized by dark brown discolouration of the embryo region and reduction of grain quality. Potential risk is the possible accumulation of mycotoxins, alternariol (AOH), alternariol-monomethyl ether (AME), tenuazonic acid (TA), and altenuene (ALT), provided by haemato-toxic, genotoxic, and mutagenic activities. One hundred and twenty durum wheat samples belonging to 30 different genotypes grown in Bologna and Modena areas, in Italy, showing black point symptoms, were analyzed for species and their mycotoxin contamination. Alternariol was selected as an indicator of the capability of the species to produce mycotoxin in vivo in field conditions. The data showed that species occurred in 118 out of 120 wheat kernels samples, with the incidence of infected kernels ranging between 1% and 26%. Moreover, AOH was detected by using a HPLC with a diode array detector (LC-DAD) in 98 out of 120 samples with values ranging between 24 and 262 µg Kg. Ninety-two representative strains, previously identified morphologically, were identified at species/section level using gene sequencing, and therefore were analyzed for their mycotoxin profiles. Eighty-four strains, phylogenetically grouped in the section, produced AOH, AME, and TA with values up to 8064, 14,341, and 3683 µg g, respectively, analyzed by using a LC-DAD. On the other hand, eight strains, included in Section, showed a very low or no capability to produce mycotoxins.
Topics: Alternaria; Edible Grain; Environmental Monitoring; Food Contamination; Italy; Mycotoxins; Phylogeny; Plant Diseases; Triticum
PubMed: 32340279
DOI: 10.3390/toxins12040275