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Leaf blotch caused by Alternaria spp. is a common disease in apple-producing regions. The disease is usually associated with one phylogenetic species and one species complex, Alternaria alternata and the Alternaria arborescens species complex ( A. arborescens SC), respectively. Both taxa may include the Alternaria 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 AMT in the case of the apple pathotype). Since 2016, leaf blotch and premature tree defoliation attributed to Alternaria spp. have been observed in apple-producing regions of central and south-eastern France. Our study aimed to identify the Alternaria 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 A. arborescens SC or A. alternata . 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 Alternaria 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 A. arborescens SC and A. alternata . 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 Alternaria apple pathotype and the taxonomic assignment of Alternaria isolates involved in Alternaria leaf blotch are discussed.

The tomato is one of the most consumed agri-food products in Lebanon. Several fungal pathogens, including Alternaria species, can infect tomato plants during the whole growing cycle. Alternaria infections cause severe production and economic losses in field and during storage. In addition, Alternaria 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 Alternaria species were detected on tomatoes, among which the most important are A. solani, A. alternata, and A. arborescens. A set of 49 Alternaria 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 Alternaria section and grouped in three well-separated sub-clades, namely A. alternata (24 out of 49), A. arborescens (12 out of 49), and A. mali morpho-species (12 out of 49). One strain showed high genetic similarity with an A.limoniasperae reference strain. Chemical analyses showed that most of the Alternaria 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−1, respectively. In addition, 66% of the strains were able to co-produce simultaneously the four mycotoxins investigated. The pathogenicity test carried out on 10 Alternaria strains, representative of phylogenetic sub-clades, revealed that they were all pathogenic on tomato fruits. No significant difference among strains was observed, although A. alternata and A. arborescens strains were slightly more aggressive than A. mali morpho-species strains. This paper reports new insights on mycotoxin profiles, genetic variability, and pathogenicity of Alternaria species on tomatoes.

As the Human Microbiome Project (HMP) progresses, the relationship between microbes and human health has been receiving increasing attention. A growing number of reports support the correlation between cancer and microbes. However, most studies have focused on bacteria, rather than fungal communities. In this study, we studied the alteration in lung mycobiome in patients with non-small-cell lung cancer (NSCLC) using metagenomic sequencing and qPCR. The higher fungal diversity and more complex network were observed in the patients with NSCLC. In addition, Alternaria arborescens was found as the most relevant fungus to NSCLC, and the enrichment of it in cancerous tissue was also detected. This study proposes that the changes in fungal communities may be closely related to lung cancer, and provides insights into further exploration the relationship between lung cancer and fungi.

Fungal leaf spot pathogens of cucurbits cause significant yield losses. They cause extensive leaf necroses and defoliation, reducing host photosynthesis. They increase risks of fruit sunscald, and can cause substantial crop damage. Alternaria cucumerina has been recognized as the causal agent of leaf spot disease of cucurbits, and recent studies have identified other Alternaria species, and other emerging pathogens such as Curvularia. This study characterized 25 isolates obtained from infected watermelon and cucumber leaves from Hungary, Spain, and Kosovo. Morphological characterization and molecular analyses using TEF1-α, HIS3, and ITS gene regions identified Alternaria alternata and A. arborescens, and for the first time on this host, the genus Curvularia. Detached leaf assays of ten isolates on 73 watermelon accessions showed variation in isolate pathogenicity. The tested Curvularia isolate was the most aggressive, followed by the A. arborescens  and A. alternata isolates, although A. alternata was the most frequently identified  species. These results highlight the potential for emerging fungal pathogens causing cucurbit leaf spot, such as Curvularia sp., and show that these fungi can cause damage on economically important plants. This study also showed differing resistance within the watermelon collection, indicating potential for the plant introduction (PI) accessions as sources of resistance breeding.

This study was aimed at identifying Alternaria species associated with heart rot disease of pomegranate fruit in southern Italy and characterizing their mycotoxigenic profile. A total of 42 Alternaria isolates were characterized. They were obtained from pomegranate fruits with symptoms of heart rot sampled in Apulia and Sicily and grouped into six distinct morphotypes based on macro- and microscopic features. According to multigene phylogenetic analysis, including internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and a SCAR marker (OPA10-2), 38 isolates of morphotypes 1 to 5 were identified as Alternaria alternata, while isolates of morphotype 6, all from Sicily, clustered within the Alternaria arborescens species complex. In particular, isolates of morphotype 1, the most numerous, clustered with the ex-type isolate of A. alternata, proving to belong to A. alternata. No difference in pathogenicity on pomegranate fruits was found between isolates of A. alternata and A. arborescens and among A. alternata isolates of different morphotypes. The toxigenic profile of isolates varied greatly: in vitro, all 42 isolates produced tenuazonic acid and most of them other mycotoxins, including alternariol, alternariol monomethyl ether, altenuene and tentoxin.

Core rot is a major contributor to postharvest losses in apples worldwide. Pathogens most commonly associated with the disease are Alternaria spp. and Penicillium spp. Although both genera show specific morphological characteristics, they can be difficult to identify to species level. In this study, Alternaria spp. (49) and Penicillium spp. isolates (97), associated with pre- and post-harvest apple core rot-symptoms and isolates from potential inoculum sources were identified using molecular methods. Initially, dry core rot causing Alternaria spp. were identified morphologically in an average of 70% of infected fruit pre-harvest and 32% postharvest. Furthermore, 78% of mouldy core rot causing pathogens were identified as Alternaria spp. preharvest and 40% postharvest. Wet core rot was associated with Penicillium spp. in 64% of cases preharvest and 36% postharvest. Species identity of a selection of samples was confirmed using the endopolygalacturonase (endo-PG) gene, the ITS region, and the anonymous genomic regions (OPA1–3, 2–1), which resulted in the identification of A. alternata, A. arborescens, A. dumosa, A. eureka and A. tenuissima. Penicillium species were identified through ITS sequencing and partial beta-tubulin polymerase chain reaction – random fragment length polymorphisms (PCR-RFLP) for the samples collected from wet core rot symptoms. Phylogenetic analyses separated the Alternaria spp. into five clades, including three separate clades for A. alternata, A. tenuissima and A. arborescens, respectively. This is the first report of A. eureka and P. polonicum as potential core rot pathogens. Phylogenetic analysis identified Penicillium ramulosum and P. expansum as the most commonly occurring species associated with WCR symptoms.

In this study, we carried out large-scale leaf spot symptom observation on vineyards in the Krasnodar Krai of Russia and determined their distribution. The incidence and severity of leaf spot were higher on the Euro-American grapevine hybrids (Bianka, Levokumskij, Avgustin, Moldova, Pervenets Magaracha, Dunavski lazur). A total of 433 isolates that belonged to the genus Alternaria were isolated from samples with leaf spot. Pathogenicity testing confirmed the ability of the representative isolates to cause necrosis on the grapevine. The isolates of Alternaria sp. were typed by the loci of internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (gapdh), Alternaria allergen a1 (Alt a1), β-tubulin (tub), and translation elongation factor (tef1). Isolates from grapevine causing leaf spot were shown to cluster with isolates of Alternaria. alternata (Fr.) Keissl. and Alternaria. arborescens E.G. Simmons species complex. Of the fungicides tested to inhibit Alternaria growth, the most effective were mixtures, such as pyrimethanil and fluopyram, cyprodinil and fludioxonil, and those that included difenoconazole. The results of the study expand our knowledge of the biodiversity of Alternaria sp. fungi and can be used to limit the spread of Alternaria leaf spot of the grapevine.

Black rot is limiting the production of sweet cherries in Italy. Dark brown to black patches and sunken lesions on fruits are the most common symptoms of Alternaria black rot on sweet cherry fruits. We isolated 180 Alternaria spp. from symptomatic cherry fruits ‘Kordia’, ‘Ferrovia’, and ‘Regina’ harvested in Northern Italy, over three years, from 2020 to 2022. The aim was to identify and characterize a selection of forty isolates of Alternaria spp. based on morphology, pathogenicity, and combined analysis of rpb2, Alt-a1, endoPG and OPA10-2. The colonies were dark greyish in the center with white margins. Ellipsoidal or ovoid shaped conidia ranging from 19.8 to 21.7 μm in length were observed under a microscope. Based on the concatenated session of four gene regions, thirty-three out of forty isolates were identified as A. arborescens species complex (AASC), and seven as A. alternata. Pathogenicity was evaluated on healthy ‘Regina’ sweet cherry fruits. All the tested strains were pathogenic on their host. This study represents the first characterization of Alternaria spp. associated with black rot of cherries in Italy and, to the best of our knowledge, it is also the first report of AASC as an agent of black rot of sweet cherries in Italy.

This study succeeded in the isolation of potent laccase endophytic fungus producer Alternaria arborescens MK629314 from medicinal plants collected from Wadi Abu Matir, Saint- Catherine-Protectorate, South Sinai-Egypt. Full physiochemical and thermodynamic characterization for A. arborescens MK629314 laccase was investigated showing the highest activity at a temperature of 50 °C and pH 5. The kinetics constants, Km (Michael's constant) and Vmax (maximum velocity) were determined to be 4 mM and 133.33 U.ml−1, respectively. Also, the thermodynamics Ea (activation energy) and Ed (activation energy of denaturation) were determined to be 15.13 and 48.85 kJ.mol−1, respectively. Thermal denaturation parameters as Kd (denaturation rate constant), T1/2 (half-life), D-values (decimal reduction time), ΔH° (enthalpy), ΔG° (Gibbs free energy), and ΔS° (entropy) were determined. The pretreatment of olive mill wastewater (OMWW) 10 and 20% with A.arborescens MK629314 caused, the maximum polyphenols removal of 63.06 and 27.29%, respectively. A.arborescens MK629314 of 50% acetone fraction succeeded in saccharification of five agricultural wastes with the highest reducing sugar recovery from cantaloupe peel which was improved by central composite design to be 240.90 mg.ml−1. A. arborescens MK629314 and its produced laccase proved to be a biological sufficient tool for the detoxification of wastewater from the olive oil industry and delignification of wastes from agriculture.Phylogenetic relationship of potent endophytic fungi for laccase production with related fungal strains based on internal transcribed spacer sequences from NCBI GenBank.

Fungal pathogens cause surface contamination and potential premature fruit spoilage of bambinella, a fruit endemic to the Maltese islands, leading to the loss of fruit during the postharvest phase. The objective of this study was to isolate, quantify, and characterize fungal contaminants of the small Maltese June Pear and describe their growth kinetics. In total, 284 fungicide-free fruits were collected over three consecutive summers (2014, 2015, 2016). The isolated fungi were identified by using forward and reverse colonial morphology. Species identification was determined using PCR-based methods. The number of CFU per square centimeter of bambinella outer skin was calculated. Mycelium diameter growth rate studies of the isolates were also carried out at seven different temperatures, ranging from 5 to 358C. Fungi isolated from bambinella included Cladosporium ramotenellum, Alternaria arborescens, Penicillium lanosum, Penicillium expansum, and Aspergillus sydowii, listed from the most abundant to the least abundant. The Rosso model was fitted to the growth kinetic data and showed that the optimal temperatures for growth of all five fungi were in the range of 20 to 228C, whereas growth was slower at temperatures below 108C and above 308C. As observed in the diameter studies, the order of highest to lowest germination rate was found to be P. expansum, A. sydowii, P. lanosum, C. ramotenellum, and A. arborescens. Germination studies showed that the highest germination rate was observed for P. lanosum, followed by A. arborescens, C. ramotenellum, P. expansum, and A. sydowii, in descending order. The highest germination lag time was observed for A. arborescens, followed by C. ramotenellum, P. expansum, P. lanosum, and A. sydowii, in ascending order.