Background: Cysteinyl leukotrienes (CysLTs) contribute to asthma pathogenesis, in part through cysteinyl leukotriene receptor 1 (CysLT1R). Recently discovered lineage-negative type 2 innate lymphoid ...cells (ILC2s) potently produce IL-5 and IL-13. Objectives: We hypothesized that lung ILC2s might be activated by leukotrienes through CysLT1R. Methods: ILC2s (Thy1.2 super(+) lineage-negative lymphocytes) and CysLT1R were detected in the lungs of wild-type, signal transducer and activator of transcription 6-deficient (STAT6 super(-/-)), and recombination-activating gene 2-deficient (RAG2 super(-/-)) mice by means of flow cytometry. T sub(H)2 cytokine levels were measured in purified lung ILC2s stimulated with leukotriene D sub(4) (LTD sub(4)) in the presence or absence of the CysLT1R antagonist montelukast. Calcium influx was measured by using Fluo-4 intensity. Intranasal leukotriene C sub(4), D sub(4), and E sub(4) were administered to naive mice, and levels of ILC2 IL-5 production were determined. Finally, LTD sub(4) was coadministered with Alternaria species repetitively to RAG2 super(-/-) mice (with ILC2s) and IL-7 receptor-deficient mice (lack ILC2s), and total ILC2 numbers, proliferation (Ki-67 super(+)), and bronchoalveolar lavage fluid eosinophil numbers were measured. Results: CysLT1R was expressed on lung ILC2s from wild-type, RAG2 super(-/-), and STAT6 super(-/-) naive and Alternaria species-challenged mice. In vitro LTD sub(4) induced ILC2s to rapidly generate high levels of IL-5 and IL-13 within 6 hours of stimulation. Interestingly, LTD sub(4), but not IL-33, induced high levels of IL-4 by ILC2s. LTD sub(4) administered in vivo rapidly induced ILC2 IL-5 production that was significantly reduced by montelukast before treatment. Finally, LTD sub(4) potentiated Alternaria species-induced eosinophilia, as well as ILC2 accumulation and proliferation. Conclusions: We present novel data that CysLT1R is expressed on ILC2s and LTD sub(4) potently induces CysLT1R-dependent ILC2 production of IL-4, IL-5, and IL-13. Additionally, LTD sub(4) potentiates Alternaria species-induced eosinophilia and ILC2 proliferation and accumulation.
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.
AIMS: To identify the taxonomic differences between phytopathogenic small‐spored Alternaria strains isolated from wheat kernels in Germany and Russia by a polyphasic approach. METHODS AND RESULTS: ...Ninety‐five Alternaria (A.) strains were characterized by their colony colour, their three‐dimensional sporulation patterns, mycotoxin production and phylogenetic relationships based on sequence variation in translation elongation factor 1‐α (TEF1‐α). The examination of toxin profiles and the phylogenetic features via TEF1‐α resulted in two distinct clusters, in each case containing Alternaria infectoria isolates (92 and 96% respectively) in the first and the Alternaria alternata, Alternaria arborescens and Alternaria tenuissima isolates (77 and 79% respectively) in the other combined cluster. The production of Alternariol, Altertoxin and Altenuene has not been reported previously in the A. infectoria species group. The isolates from Germany and Russia differ slightly in species composition and mycotoxin production capacity. CONCLUSIONS: We identified that the A. infectoria species group can be differentiated from the A. alternata, A. arborescens and A. tenuissima species group by colour, low mycotoxin production and by the sequence variation in TEF1‐α gene. SIGNIFICANCE AND IMPACT OF THE STUDY: These results allow a reliable toxic risk assessment when detecting different Alternaria fungi on cereals.
Leaf blotch caused by
spp. is a common disease in apple-producing regions. The disease is usually associated with one phylogenetic species and one species complex,
and the
species complex (
SC), ...respectively. Both taxa may include the
apple pathotype, a quarantine or regulated pathogen in several countries. The apple pathotype is characterized by the production of a host-selective toxin (HST) which is involved in pathogenicity towards the apple. A cluster of genes located on conditionally dispensable chromosomes (CDCs) is involved in the production of this HST (namely
in the case of the apple pathotype). Since 2016, leaf blotch and premature tree defoliation attributed to
spp. have been observed in apple-producing regions of central and south-eastern France. Our study aimed to identify the
species involved in apple tree defoliation and assess the presence of the apple pathotype in French orchards. From 2016 to 2018, 166 isolates were collected and identified by multi-locus sequence typing (MLST). This analysis revealed that all these French isolates belonged to either the
SC or
. Specific PCR detection targeting three genes located on the CDC did not indicate the presence of the apple pathotype in France. Pathogenicity was assessed under laboratory conditions on detached leaves of Golden Delicious and Gala apple cultivars for a representative subset of 28
isolates. All the tested isolates were pathogenic on detached leaves of cultivars Golden Delicious and Gala, but no differences were observed between the pathogenicity levels of
SC and
. However, the results of our pathogenicity test suggest that cultivar Golden Delicious is more susceptible than Gala to Alternaria leaf blotch. Implications in the detection of the
apple pathotype and the taxonomic assignment of
isolates involved in Alternaria leaf blotch are discussed.
In this paper, thermal (8-13 µm) and hyperspectral imaging in visible and near infrared (VNIR) and short wavelength infrared (SWIR) ranges were used to elaborate a method of early detection of biotic ...stresses caused by fungal species belonging to the genus Alternaria that were host (Alternaria alternata, Alternaria brassicae, and Alternaria brassicicola) and non-host (Alternaria dauci) pathogens to oilseed rape (Brassica napus L.). The measurements of disease severity for chosen dates after inoculation were compared to temperature distributions on infected leaves and to averaged reflectance characteristics. Statistical analysis revealed that leaf temperature distributions on particular days after inoculation and respective spectral characteristics, especially in the SWIR range (1000-2500 nm), significantly differed for the leaves inoculated with A. dauci from the other species of Alternaria as well as from leaves of non-treated plants. The significant differences in leaf temperature of the studied Alternaria species were observed in various stages of infection development. The classification experiments were performed on the hyperspectral data of the leaf surfaces to distinguish days after inoculation and Alternaria species. The second-derivative transformation of the spectral data together with back-propagation neural networks (BNNs) appeared to be the best combination for classification of days after inoculation (prediction accuracy 90.5%) and Alternaria species (prediction accuracy 80.5%).
Abstract
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. alternataHSTs 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. alternataHSTs, 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.
We report the biosynthetic pathways of cyanobacterial toxins and describe the evolutionary scenarios that have led to the emergence, diversification and loss of such gene clusters.
Alternaria is one of the important allergenic fungal spores having special role in childhood asthma. Aerodynamic particle of <10 mu m diameter (PM sub(10)) and ozone exacerbate respiratory conditions ...including asthma. There is no documentation determining the role of airborne concentration of Alternaria conidia, pollutants like PM sub(10) and ozone and weather on school-age (5-18 years) children causing life-threatening episodes requiring emergency hospitalization for asthma in the megacity of Kolkata, Eastern India. We examined the relationship of daily hospitalization for asthma in school-age children and daily concentration of outdoor Alternaria conidia, ozone, PM sub(10) and weather parameters in the atmosphere of Kolkata during 2010 using nonparametric generalized additive model (GAM). After a baseline survey (2008-2009), asthma hospitalization data for school-age children (based on case history and symptom-medication) were collected from two important city hospitals near study area in 2010. Daily Alternaria concentration was recorded using Burkard volumetric sampler. Its allergenic potential was confirmed by skin reactivity. Ozone and PM sub(10) concentration data were collected from West Bengal Pollution Control Board. The daily time series analyses of data were performed using GAM. There are two peak seasons of asthma hospitalization, one in spring-early summer (end of March to mid April) and other in autumn (mid September-October). In GAM analyses, Alternaria conidia, ozone and PM sub(10) were found to be significant both in spline and LOcal regrESSion smoothing method. Airborne Alternaria conidia, ozone and PM sub(10) in the city of Kolkata are found to have effect on school-age children with asthma and appear responsible for severe attacks leading to hospitalization.
Alternaria species have the ability to produce a variety of secondary metabolite, which plays important roles in food safety. Argentina is the second largest exporter of fresh and processed food ...products to Europe, however, few studies on Alternaria mycotoxins and other bioactive secondary metabolites have been carried out on Argentinean cereals, fruit and vegetables. Knowing the full chemical potential and the distribution of Alternaria spp. on crops, it is necessary to establish a toxicological risk assessment for food products for human consumption. In the present study, 87 Alternaria strains from different substrates (tomato, wheat, blueberries and walnuts) were characterized according to morphology and metabolite production. Aggressive dereplication (accurate mass, isotopic patterns and lists of all described compounds from Alternaria) was used for high-throughput evaluation of the chemical potential. Four strains belonged to the Alternaria infectoria sp.-grp., 6 to the Alternaria arborescens sp.-grp., 6 showed a sporulation pattern similar to that of “M” according to Simmons, 1 to that of Alternaria vaccinii, and the remaining 70 constituted a diverse group belonging to morphological groups “G” and “H”. The cluster analysis yielded 16 almost identical dendrograms and grouped the Alternaria strains into four clusters and 11 singletons and outlier groups. The chemical analysis showed that AOH and AME were the most common metabolites produced, followed by TEN, ALXs and TeA. The A. infectoria sp.-grp. had no metabolites in common with the rest of the strains. Several secondary metabolites isolated from large-spored Alternaria species or other fungal genera were detected, such as dehydrocurvularin, pyrenochaetic acid and alternarienonic acid. The strains isolated from tomato produced lower amounts of metabolites than strains from blueberries, walnut and wheat, although individual strains from tomato produced the highest amount of some metabolites. The A. infectoria sp.-grp. was unique to cereals, whereas strains classified as belonging to the A. arborescens sp.-grp or having sporulation pattern “M” were only isolated from tomatoes. Otherwise, no clear association between substrate and identity could be found. The analyses in the study show that at least 75% of the Argentinean strains are able to produce potential mycotoxins.
•87 Alternaria strains from Argentinean foods were morphologically characterized.•Aggressive dereplication was used to evaluate the strains' chemical potential.•75% of the Argentinean Alternaria strains are able to produce potential mycotoxins.
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