Publications by authors named "Maria Lodovica Gullino"

71 Publications

First report of causing root and crown rot on maize in Italy.

Plant Dis 2021 Jun 15. Epub 2021 Jun 15.

UNIVERSITA' DI TORINO, AGROINNOVA, VIA L. DA VINCI 44, GRUGLIASCO, Italy, 10095;

Maize (Zea mays L.) is a cereal crop of great economic importance in Italy; production is currently of 62,587,469 t, with an area that covers 628,801 ha, concentrated in northern Italy (ISTAT 2020). Fusarium species are associated with root and crown rot causing failures in crop establishment under high soil moisture. In 2019 maize seedlings collected in a farm located in San Zenone degli Ezzelini (VI, Italy) showed root and crown rot symptoms with browning of the stem tissues, wilting of the seedling, and collapsing due to the rotting tissues at the base of the stem. The incidence of diseased plants was approximately 15%. Seedlings were cleaned thoroughly from soil residues under tap water. Portions (about 3-5 mm) of tissue from roots and crowns of the diseased plants were cut and surface disinfected with a water solution of NaClO at 0.5% for 2 minutes and rinsed in sterile H20. The tissue fragments were plated on Potato Dextrose Agar (PDA) amended with 50 mg/l of streptomycin sulfate and incubated for 48-72 hours at 25oC. Over the 80 tissue fragments plated, 5% were identified as Fusarium verticillioides, 60% as Fusarium spp., 35% developed saprophytes. Fusarium spp. isolates that showed morphological characteristics not belonging to known pathogenic species on maize were selected and used for further investigation while species belonging to F. oxysporum were discarded. Single conidia of the Fusarium spp. colonies were cultured on PDA and Carnation Leaf Agar (CLA) for pathogenicity tests, morphological and molecular identification. The colonies showed white to pink, abundant, densely floccose to fluffy aerial mycelium. Colony reverse showed light violet pigmentation, in rings on PDA. On CLA the isolates produced slightly curved macronidia with 3 septa 28.1 - 65.5 µm long and 2.8-6.3 µm wide (n=50). Microconidia were cylindrical, aseptate, 4.5 -14.0 µm long and 1.5-3.9 µm wide (n=50). Spherical clamydospores were 8.8 ± 2.5 µm size (n=30), produced singly or in pairs on the mycelium, according to the description by Skovgaard et al. (2003) for F. commune. The identity of two single-conidia strains was confirmed by sequence comparison of the translation elongation factor-1α (tef-1α), and RNA polymerase II subunit (rpb2) gene fragments (O'Donnell et al. 2010). BLASTn searches of GenBank, and Fusarium-ID database, using the partial tef-1α (MW419921, MW419922) and rpb2 (MW419923, MW419924) sequences of representative isolate DB19lug07 and DB19lug20, revealed 99% identity for tef-1α and 100% identity to F. commune NRRL 28387(AF246832, AF250560). Pathogenicity tests were carried out by suspending conidia from a 10-days old culture on PDA in sterile H2O to 5×104 CFU/ml. Fifty seeds were immersed in 50 ml of the conidial suspension of each isolate for 24 hours and in sterile water (Koch et al. 2020). The seeds were drained, dried at room temperature, and sown in trays filled with a steamed mix of white peat and perlite, 80:20 v/v, and maintained at 25°C and RH of 80-85% for 14 days with 12 hours photoperiod. Seedlings were extracted from the substrate, washed under tap water, and observed for the presence of root and crown rots like the symptoms observed on the seedlings collected in the field. Control seedlings were healthy and F. commune was reisolated from the symptomatic ones and identified by resequencing of tef-1α gene. F. commune has been already reported on maize (Xi et al. 2019) and other plant species, like soybean (Ellis et al. 2013), sugarcane (Wang et al. 2018), potato (Osawa et al. 2020), indicating that some attention must be paid in crop rotation and residue management strategies. To our knowledge this is the first report of F. commune as a pathogen of maize in Italy. References Ellis M L et al. 2013. Plant Disease, 97, doi: 10.1094/PDIS-07-12-0644-PDN. ISTAT. 2020. http://dati.istat.it/Index.aspx?QueryId=33702. Accessed December 28, 2020. Koch, E. et al. 2020. Journal of Plant Diseases and Protection. 127, 883-893 doi: 10.1007/s41348-020-00350-w O'Donnell K et al. 2010. J. Clin. Microbiol. 48:3708. https://doi.org/10.1128/JCM.00989-10 Osawa H et al. 2020. Journal of General Plant Pathology, doi.org/10.1007/s10327-020-00969-5. Skovgaard K 2003. Mycologia, 95:4, 630-636, DOI: 10.1080/15572536.2004.11833067. Wang J et al. 2018. Plant Disease, 102, doi/10.1094/PDIS-07-17-1011-PDN Xi K et al. 2019. Plant Disease, 103, doi/10.1094/PDIS-09-18-1674-PDN.
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http://dx.doi.org/10.1094/PDIS-01-21-0075-PDNDOI Listing
June 2021

First Report of Brown Rot Caused by on Apple in Italy.

Plant Dis 2021 Jun 7. Epub 2021 Jun 7.

University of Torino, DISAFA - Dept. Agricultural, Forestry and Food Sciences, Largo Braccini 2, Grugliasco, TO, Italy, 10095.

Brown rot is a common apple disease in Italy, caused by Monilinia fructicola, M. laxa and M. fructigena (Martini et al. 2013). In September 2020, in a 'Jeromine' apple orchard under integrated pest management located in Scarnafigi (44°39'N, 7°33'E, north-western of Italy), fruits (8.6%) showing brown to blackish firm lesions (6.0 to 8.0 cm diameter) were observed. In some fruits, rots were covered by yellowish stromata. Two isolates (MPI1; MPI2) were obtained from two symptomatic apples and cultured on potato dextrose agar (PDA) for 7 days at 25°C in 12-h light/12-h dark regime. A white-to-greyish mycelium with slightly undulate margins and irregular, black stromata developed on PDA after 12 days incubation. Conidia, observed in branched monilioid chains, (Suppl. Fig. 1) were one-celled, globose, limoniform, hyaline, 38 to 58 μm (mean: 48) × 20 to 44 μm (mean: 33). Based on morphology, the isolates were tentatively identified as Monilinia polystroma (G.C.M. Leeuwen) Kohn. A polymerase chain reaction with primers ITS1 and ITS4 was performed on internal transcribed spacer (ITS) region 1 and 2 and 5.8S gene. The sequenced amplicons (435 bp - 445 bp; GenBank Accession No. MW600854; MW600855) showed 100% identity to the reference isolate of M. polystroma (HQ846944) and to other isolates from apples (AM937114; JX315717) and plum (GU067539). The ITS region of M. polystroma had five nucleotides to distinguish it from the closest species M. fructigena (Zhu et al. 2016; MH862738) (Suppl. Fig. 2). The pathogenicity of both isolates was tested on mature 'Jeromine' apples (10.1% total soluble solids). Three replicates of six apples per isolate were surface disinfected with 1% NaClO. A mycelial plug (5 mm) from colony grown on PDA was inserted using a cork borer into a hole (6 mm) in each fruit (Vasić et al. 2016). Apples inoculated with sterile PDA plugs were used as control. Fruits were placed at 22 ± 1 °C, 85% relative humidity and 12 h light/12 h dark regime. Lesion size was measured after 3, 6 and 9 days of incubation. All inoculated fruits developed typical brown rot symptoms 6 days after inoculation and yellowish stromata appeared on the surface; control fruit remained healthy (Suppl. Fig. 3). The virulence of both isolates was statistically similar (Suppl. Table 1). M. polystroma was reisolated from all inoculated fruits and confirmed by molecular methods. This is the first report of M. polystroma on apple in Italy. M. polystroma was previously reported on apple in Hungary (Petróczy et al. 2009), on apricot in Switzerland (Hilber-Bodmer et al. 2012), on peach and pear in Italy (Martini et al. 2014; 2015), on plum in China (Zhu et al. 2016), and on apple in Serbia (Vasić et al. 2018). The emergence of this pathogen for pome and stone fruit production in Europe stimulates to study its biology and epidemiology, and its fitness and management, as compared to the other endemic Monilinia species.
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http://dx.doi.org/10.1094/PDIS-03-21-0548-PDNDOI Listing
June 2021

Genetic Diversity and Pathogenicity of Species Associated with Symptomatic Citrus Plants in Europe.

Plants (Basel) 2021 Mar 5;10(3). Epub 2021 Mar 5.

Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.

This study represents the first survey studying the occurrence, genetic diversity, and pathogenicity of Botryosphaeriaceae species associated with symptomatic citrus species in citrus-production areas in five European countries. Based on morphological features and phylogenetic analyses of internal transcribed spacer (ITS) of nuclear ribosomal DNA (nrDNA), translation elongation factor 1-alpha () and β-tubulin () genes, nine species were identified as belonging to the genera , , and . Isolates of and were the most frequently detected, while had the widest distribution, occurring in four of the five countries sampled. Representative isolates of the nine Botryosphaeriaceae species used in the pathogenicity tests caused similar symptoms to those observed in nature. Isolates assayed were all re-isolated, thereby fulfilling Koch's postulates. Isolates of and are recorded for the first time on citrus and all species found in our study, except , are reported for the first time on citrus in Europe.
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http://dx.doi.org/10.3390/plants10030492DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7999779PMC
March 2021

Characterization of Species Associated with Heart Rot of Pomegranate Fruit.

J Fungi (Basel) 2021 Feb 27;7(3). Epub 2021 Feb 27.

Department of Agriculture, Food and Environment, University of Catania, 95123 Catania, Italy.

This study was aimed at identifying species associated with heart rot disease of pomegranate fruit in southern Italy and characterizing their mycotoxigenic profile. A total of 42 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 , while isolates of morphotype 6, all from Sicily, clustered within the species complex. In particular, isolates of morphotype 1, the most numerous, clustered with the ex-type isolate of , proving to belong to . . No difference in pathogenicity on pomegranate fruits was found between isolates of and and among 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.
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http://dx.doi.org/10.3390/jof7030172DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7997272PMC
February 2021

Monitoring and Surveillance of Aerial Mycobiota of Rice Paddy through DNA Metabarcoding and qPCR.

J Fungi (Basel) 2020 Dec 17;6(4). Epub 2020 Dec 17.

School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.

The airborne mycobiota has been understudied in comparison with the mycobiota present in other agricultural environments. Traditional, culture-based methods allow the study of a small fraction of the organisms present in the atmosphere, thus missing important information. In this study, the aerial mycobiota in a rice paddy has been examined during the cropping season (from June to September 2016) using qPCRs for two important rice pathogens ( and ) and by using DNA metabarcoding of the fungal ITS region. The metabarcoding results demonstrated a higher alpha diversity (Shannon-Wiener diversity index H' and total number of observed species) at the beginning of the trial (June), suggesting a higher level of community complexity, compared with the end of the season. The main taxa identified by HTS analysis showed a shift in their relative abundance that drove the cluster separation as a function of time and temperature. The most abundant OTUs corresponded to genera such as , , or . Changes in the mycobiota composition were clearly dependent on the average air temperature with a potential impact on disease development in rice. In parallel, oligotyping analysis was performed to obtain a sub-OTU identification which revealed the presence of several oligotypes of and with relative abundance changing during monitoring.
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http://dx.doi.org/10.3390/jof6040372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7766667PMC
December 2020

Biological and molecular interplay between two viruses and powdery and downy mildews in two grapevine cultivars.

Hortic Res 2020 Nov 1;7(1):188. Epub 2020 Nov 1.

Institute for Sustainable Plant Protection, National Research Council (IPSP-CNR), Strada delle Cacce 73, 10135, Torino, Italy.

Grapevine may be affected simultaneously by several pathogens whose complex interplay is largely unknown. We studied the effects of infection by two grapevine viruses on powdery mildew and downy mildew development and the molecular modifications induced in grapevines by their multiple interactions. Grapevine fanleaf virus (GFLV) and grapevine rupestris stem pitting-associated virus (GRSPaV) were transmitted by in vitro-grafting to Vitis vinifera cv Nebbiolo and Chardonnay virus-free plantlets regenerated by somatic embryogenesis. Grapevines were then artificially inoculated in the greenhouse with either Plasmopara viticola or Erysiphe necator spores. GFLV-infected plants showed a reduction in severity of the diseases caused by powdery and downy mildews in comparison to virus-free plants. GFLV induced the overexpression of stilbene synthase genes, pathogenesis-related proteins, and influenced the genes involved in carbohydrate metabolism in grapevine. These transcriptional changes suggest improved innate plant immunity, which makes the GFLV-infected grapevines less susceptible to other biotic attacks. This, however, cannot be extrapolated to GRSPaV as it was unable to promote protection against the fungal/oomycete pathogens. In these multiple interactions, the grapevine genotype seemed to have a crucial role: in 'Nebbiolo', the virus-induced molecular changes were different from those observed in 'Chardonnay', suggesting that different metabolic pathways may be involved in protection against fungal/oomycete pathogens. These results indicate that complex interactions do exist between grapevine and its different pathogens and represent the first study on a topic that still is largely unexplored.
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http://dx.doi.org/10.1038/s41438-020-00413-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603506PMC
November 2020

Development of PCR, LAMP and qPCR Assays for the Detection of Aflatoxigenic Strains of and in Hazelnut.

Toxins (Basel) 2020 11 30;12(12). Epub 2020 Nov 30.

Centre of Competence for the Innovation in the Agro-environmental Sector-AGROINNOVA, University of Turin, via Paolo Braccini 2, I-10095 Grugliasco, Italy.

and are two species able to produce aflatoxins in foodstuffs, and in particular in hazelnuts, at harvest and during postharvest phase. As not all the strains of these species are aflatoxin producers, it is necessary to develop techniques that can detect aflatoxigenic from not aflatoxigenic strains. Two assays, a LAMP (loop-mediated isothermal amplification) and a real time PCR with TaqMan probe were designed and validated in terms of specificity, sensitivity, reproducibility, and repeatability. The capability of the strains to produce aflatoxins was measured in vitro and both assays showed to be specific for the aflatoxigenic strains of and . The limit of detection of the LAMP assay was 100-999 picograms of DNA, while the qPCR detected 160 femtograms of DNA in hazelnuts. Both techniques were validated using artificially inoculated hazelnuts and naturally infected hazelnuts. The qPCR was able to detect as few as eight cells of aflatoxigenic in naturally infected hazelnut. The combination of the LAMP assay, which can be performed in less than an hour, as screening method, with the high sensitivity of the qPCR, as confirmation assay, is able to detect aflatoxigenic strains already in field, helping to preserve the food safety of hazelnuts.
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http://dx.doi.org/10.3390/toxins12120757DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7761073PMC
November 2020

The Molecular Priming of Defense Responses is Differently Regulated in Grapevine Genotypes Following Elicitor Application against Powdery Mildew.

Int J Mol Sci 2020 Sep 15;21(18). Epub 2020 Sep 15.

Institute for Sustainable Plant Protection, National Research Council (IPSP-CNR), Strada delle Cacce 73, 10135 Torino, Italy.

Molecular changes associated with response to powdery mildew (PM) caused by have been largely explored in cultivars, but little is known on transcriptional and metabolic modifications following application of resistance elicitors against this disease. In this study, the whole transcriptome sequencing, and hormone and metabolite analyses were combined to dissect long-term defense mechanisms induced by molecular reprogramming events in PM-infected 'Moscato' and 'Nebbiolo' leaves treated with three resistance inducers: acibenzolar-S-methyl, potassium phosphonate, and laminarin. Although all compounds were effective in counteracting the disease, acibenzolar-S-methyl caused the most intense transcriptional modifications in both cultivars. These involved a strong down-regulation of photosynthesis and energy metabolism and changes in carbohydrate accumulation and partitioning that most likely shifted the plant growth-defense trade-off towards the establishment of disease resistance processes. It was also shown that genotype-associated metabolic signals significantly affected the cultivar defense machinery. Indeed, 'Nebbiolo' and 'Moscato' built up different defense strategies, often enhanced by the application of a specific elicitor, which resulted in either reinforcement of early defense mechanisms (e.g., epicuticular wax deposition and overexpression of pathogenesis-related genes in 'Nebbiolo'), or accumulation of endogenous hormones and antimicrobial compounds (e.g., high content of abscisic acid, jasmonic acid, and viniferin in 'Moscato').
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http://dx.doi.org/10.3390/ijms21186776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7555711PMC
September 2020

Development of a Sensitive TaqMan qPCR Assay for Detection and Quantification of in Apple Leaves and Fruit and in Air Samples.

Plant Dis 2020 Nov 9;104(11):2851-2859. Epub 2020 Sep 9.

Department of Agricultural, Forestry and Food Sciences (DiSAFA), University of Torino, via Paolo Braccini 2, 10095, Grugliasco, Italy.

A TaqMan quantitative PCR (qPCR) assay based on the translation elongation factor 1-α gene was developed for the quantification of in leaves and fruits of × and in spore trap samples. The designed primers and hydrolysis probe amplified a specific 86-bp fragment for . The specificity of the assay was tested using 35 strains of and 20 different fungal species, including common pathogens of apple and other species of . The limit of detection was 20 fg, which is lower than a single genome of . The selectivity of the assay was tested using DNA from three cultivars of × , and no influence on pathogen amplification was found. The assay was also validated for repeatability and reproducibility. With this assay, it was possible to detect and quantify in four cultivars (Ambrosia, Florina, Golden Delicious, and Mondial Gala) in both symptomatic and asymptomatic leaves and in symptomatic Golden Delicious apple fruit stored for 2 months. Furthermore, the assay was successfully tested on spore trap samples originating from apple orchards. The quantification of the molecular assay when compared with the estimated number of cells, using an optical microscope, showed a correlation coefficient of 0.8186. The developed technique could be used to detect in asymptomatic samples without any cross-reaction with other fungal species. Furthermore, to improve the efficacy of disease management with a timely application of fungicides, this assay could be used for the analysis of spore trap samples by using an implemented extraction method.
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http://dx.doi.org/10.1094/PDIS-10-19-2160-REDOI Listing
November 2020

A Compost Treatment Acts as a Suppressive Agent in Pathosystem by Modifying the Rhizosphere Microbiota.

Front Plant Sci 2020 24;11:885. Epub 2020 Jun 24.

AGROINNOVA - Centre of Competence for the Innovation in the Agro-Environmental Sector, University of Turin, Turin, Italy.

Leonian (PHC) is a filamentous pathogen oomycete that causes root, fruit, foliar and crown rot over a wide host range, including the economically and nutritionally important summer squash ( var. L.) crop. PHC chemical control strategies are difficult to adopt, due to the limited number of registered chemicals that are permitted and the scalar harvest system. For these reasons, other strategies, such as the use of waste-based composts that can act as suppressive agents against several soilborne pathogens, have been studied intensively. It is well known that compost's microbiota plays an important role to confer its suppressive ability. In this study, four different composts were analyzed with both 16S rRNA gene and 18S rRNA gene real-time PCR amplification and with 26S gene amplicon-based sequencing; the total abundance of the bacterial and fungal communities was found to be higher compared to literature, thus confirming that the four composts were a good inoculum source for agricultural applications. The core mycobiota was mainly composed of 31 genera; nevertheless, it was possible to observe a clear predominance of the same few taxa in all the composts. The four composts were then tested, at different concentrations (1-10-20% v/v), to establish their ability to confer suppressiveness to the (PHC) - pathosystem in controlled greenhouse pot trials. A total of 12 compost mixtures were considered, and of these, one (-enriched compost at 10% v/v) was able to statistically reduce the disease incidence caused by PHC (by 50% compared to the untreated control). Hence, the microbiota composition of the most effective compost treatment was investigated and compared with untreated and chemical (metalaxyl) controls. Mycobiota sequencing showed genera differences between the three treatments, with relative abundances of several fungal genera that were significantly different among the samples. Moreover, PCA analyses clustered the compost treatment differently from the chemical and the untreated controls. These findings suggest that suppressive activity of a compost is strictly influenced by its microbiota and the applied dosage, but the ability to induce a shaping in the rhizosphere microbial composition is also required.
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http://dx.doi.org/10.3389/fpls.2020.00885DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327441PMC
June 2020

Alternaria Leaf Spot Caused by Species: An Emerging Problem on Ornamental Plants in Italy.

Plant Dis 2020 Aug 25;104(8):2275-2287. Epub 2020 Jun 25.

AGROINNOVA - Centre of Competence for the Innovation in the Agro-environmental Sector, Università di Torino, 10095 Grugliasco (TO), Italy.

Serious outbreaks of Alternaria leaf spot and plant decay have recently been recorded on several ornamental plants in the Biella Province (Northern Italy). Twenty-two fungal isolates were obtained from infected plant tissues from 13 ornamental hosts. All the isolates were identified morphologically as small-spored species. Multilocus sequence typing, carried out by means of ITS, , , , , and OPA10-2, assigned 19 isolates as , two isolates as belonging to the species complex, and one isolate as an unknown sp. Haplotype analyses of ornamental and reference isolates from 12 countries identified 14 OPA10-2 and 11 haplotypes showing a relatively high haplotype diversity. A lack of host specialization or geographic distribution was observed. The host range of the studied isolates expanded in cross-pathogenicity assays, and more aggressiveness was frequently observed on the experimental plants than on the host plants from which the fungal isolates were originally isolated. High disease severity, population expansion, intraspecies diversity, and increased range of experimental hosts were seen in the emergence of Alternaria disease on ornamentals. More epidemiological and molecular studies should be performed to better understand these diseases, taking into consideration factors such as seed transmission and ongoing climate changes.
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http://dx.doi.org/10.1094/PDIS-02-20-0399-REDOI Listing
August 2020

Impact of Chemical and Alternative Fungicides Applied to Grapevine cv Nebbiolo on Microbial Ecology and Chemical-Physical Grape Characteristics at Harvest.

Front Plant Sci 2020 29;11:700. Epub 2020 May 29.

Department of Agricultural, Forest and Food Sciences, University of Turin, Grugliasco, Italy.

Viticulture is a cropping system in which treatment against fungal diseases (in particular powdery and downy mildews) can be extremely frequent. Accordingly, a reduction in antimicrobial treatments and the application of environmentally-friendly compounds are becoming increasingly important for a more sustainable viticulture. In addition to their effect against pathogens, the impact of these products on the quality of the grapes is very important for the oenological industries, but unfortunately at present few data are available. We evaluated the effect of the application of biocontrol products and resistance inducers in the vineyard on the mechanical properties, microbial ecology, technological and phenolic maturity of "Nebbiolo" grapes at harvest. The yield and vigor of vines were not influenced by the treatments, nor were the production of primary and secondary metabolites. However, the active ingredients influenced the mechanical properties of the skin (hardness and thickness). A significant hardening of the skin was detected when laminarin and chito-oligosaccharides were used, and sulfur induced a thickening of the skin with potential consequences for wine quality. Furthermore, the yeast community present on grape berries was influenced by the treatments. The abundance of , the dominant species on the grape berry, changed in response to the compounds used. In addition, sp. was reduced in some treatments with a potentially positive effect on the quality and the safety of the grapes. This study provides an overview of the effect of biocontrol products and resistance inducers on microbial ecology and "Nebbiolo" grape quality, contributing to the establishment of more sustainable and effective defense strategies in viticulture.
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http://dx.doi.org/10.3389/fpls.2020.00700DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7272676PMC
May 2020

Characterization of Population Associated with Black Spot of Sweet Basil () in Northern Italy.

Plants (Basel) 2020 May 22;9(5). Epub 2020 May 22.

Agroinnova-Centre of Competence for the Innovation in the Agro-Environmental Sector, University of Turin, 10095 Turin, Italy.

Black spot is a major foliar disease of sweet basil () present in a typical cultivation area of northern Italy, including the Liguria and southern Piedmont regions, where this aromatic herb is an economically important crop. In this study, 15 isolates obtained from sweet basil plants with symptoms of black spot sampled in this area were characterized morphologically and by nuclear DNA analysis using internal transcribed spacers (ITS) and intervening 5.8S nrDNA as well as part of the β-tubulin gene (TUB2) regions as barcode markers. Analysis revealed all but one isolate belonged to the recently described species of the species complex. Only one isolate was identified as (). In pathogenicity tests on sweet basil, both and isolates incited typical symptoms of black spot, showing that although prevails in this basil production area, it is not the sole causal agent of black spot in northern Italy. While no other hosts of are known worldwide, the close related species has a broad host range, suggesting a speciation process of within this species complex driven by adaptation to the host.
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http://dx.doi.org/10.3390/plants9050654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7285085PMC
May 2020

HPLC-MS/MS Method for the Detection of Selected Toxic Metabolites Produced by spp. in Nuts.

Toxins (Basel) 2020 05 8;12(5). Epub 2020 May 8.

Centre of Competence for the Innovation in the agro-environmental Sector (AGROINNOVA), University of Torino, Largo P. Braccini 2, 10095 Grugliasco (TO), Italy.

spp. are emerging as producers of mycotoxins and other toxic metabolites in nuts. A HPLC-MS/MS method was developed to detect 19 metabolites produced by spp. on chestnuts, hazelnuts, walnuts and almonds. Two extraction methods were developed, one for chestnuts and one for the other three nuts. The recovery, LOD, LOQ and matrix effect were determined for each analyte and matrix. Correlation coefficients were always >99.99%. In walnuts, a strong signal suppression was observed for most analytes and patulin could not be detected. Six strains: , , , , and , isolated from chestnuts, were inoculated on four nuts. Chestnuts favored the production of the largest number of toxic metabolites. The method was used for the analysis of 41 commercial samples: 71% showed to be contaminated by -toxins. Cyclopenin and cyclopenol were the most frequently detected metabolites, with an incidence of 32% and 68%, respectively. Due to the risk of contamination of nuts with toxins, future studies and legislation should consider a larger number of mycotoxins.
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http://dx.doi.org/10.3390/toxins12050307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7290882PMC
May 2020

Effect of Drying Temperatures and Exposure Times on Aspergillus flavus Growth and Aflatoxin Production on Artificially Inoculated Hazelnuts.

J Food Prot 2020 Jul;83(7):1241-1247

AGROINNOVA-Centre of Competence for the Innovation in the Agroenvironmental Sector, Largo Paolo Braccini 2, 10095 Grugliasco, Italy (ORCID: https://orcid.org/0000-0001-5207-9345 [D.S.]).

Abstract: Aspergillus flavus may colonize hazelnuts and produce aflatoxins in the field and during storage. The main purpose of this study was to investigate the influence of drying temperature and exposure times on the viability of A. flavus and its ability to produce aflatoxins during the drying process and storage. Hazelnuts were inoculated with A. flavus and dried at different temperatures to reach 6% moisture content and a water activity (aw) of 0.71, a commercial requirement to avoid fungal development and aflatoxin contamination. Hazelnuts were dried at 30, 35, 40, 45, and 50°C and subsequently stored at 25°C for 14 days. After drying at 30, 35, and 40°C, increased amounts of A. flavus were evident, with the highest concentration occurring after drying at 35°C ([6.1 ± 2.4] × 106A. flavus CFU/g). At these temperatures, aflatoxins were detected only at 30 and 35°C. Aflatoxins, however, were present at higher levels after drying at 30°C, with concentrations of 1.93 ± 0.77 μg/g for aflatoxin B1 (AFB1) and 0.11 ± 0.04 μg/g for aflatoxin B2 (AFB2). After 14 days of storage, the highest A. flavus concentration and the highest levels of mycotoxins were detected in samples treated at 35°C ([8.2 ± 2.1] × 107A. flavus CFU/g and 9.30 ± 1.58 μg/g and 0.89 ± 0.08 μg/g for AFB1 and AFB2, respectively). In hazelnuts dried at 45 or 50°C, no aflatoxins were found either after drying or storage, and a reduction of A. flavus viable conidia was observed, suggesting that a shorter and warmer drying is essential to guarantee nut safety. The lowest temperature that guarantees the lack of aflatoxins should be selected to maintain the organoleptic quality of hazelnuts. Therefore, 45°C should be the recommended drying temperature to limit A. flavus growth and aflatoxin contamination on hazelnuts.

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http://dx.doi.org/10.4315/JFP-20-061DOI Listing
July 2020

Grapevine Phyllosphere Community Analysis in Response to Elicitor Application against Powdery Mildew.

Microorganisms 2019 Dec 7;7(12). Epub 2019 Dec 7.

Research Centre for Viticulture and Enology, Council for Agricultural Research and Economics (CREA-VE), Via XXVIII Aprile 26, 31015 Conegliano, Italy.

The reduction of antimicrobial treatments and mainly the application of environmentally friendly compounds, such as resistance elicitors, is an impelling challenge to undertake more sustainable agriculture. We performed this research to study the effectiveness of non-conventional compounds in reducing leaf fungal attack and to investigate whether they influence the grape phyllosphere. Pathogenicity tests were conducted on potted "Nebbiolo" and "Moscato" cultivars infected with the powdery mildew agent () and treated with three elicitors. Differences in the foliar microbial community were then evaluated by community-level physiological profiling by using Biolog EcoPlates, high throughput sequencing of the Internal Transcribed Spacer (ITS) region, and RNA sequencing for the viral community. In both cultivars, all products were effective as they significantly reduced pathogen development. EcoPlate analysis and ITS sequencing showed that the microbial communities were not influenced by the alternative compound application, confirming their specific activity as plant defense elicitors. Nevertheless, "Moscato" plants were less susceptible to the disease and presented different phyllosphere composition, resulting in a richer viral community, when compared with the "Nebbiolo" plants. The observed effect on microbial communities pointed to the existence of distinct genotype-specific defense mechanisms independently of the elicitor application.
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http://dx.doi.org/10.3390/microorganisms7120662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6956034PMC
December 2019

Expression and role of CYP505A1 in pathogenicity of Fusarium oxysporum f. sp. lactucae.

Biochim Biophys Acta Proteins Proteom 2020 01 3;1868(1):140268. Epub 2019 Sep 3.

Department of Life Sciences and Systems Biology, University of Torino, Torino, Italy. Electronic address:

Background: Cytochrome P450 enzymes (CYPs) are monooxygenases present in every domain of life. In fungi CYPs are involved in virulence. Fusarium wilt of lettuce, caused by F. oxysporum f. sp. lactucae, is the most serious disease of lettuce. F. oxysporum f.sp. lactucae MSA35 is an antagonistic fungus. Pathogenic formae specialis of F. oxysporum possess a CYP belonging to the new family CYP505. This enzyme hydroxylates saturated fatty acids that play a role in plant defence.

Methods: Molecular tools were adopted to search for cyp505 gene in MSA35 genome. cyp505 gene expression analysis in pathogenic and antagonistic Fusarium was performed. The enzyme was expressed in its recombinant form and used for catalytic reactions with fatty acids, the products of which were characterized by mass spectrometry analysis.

Results: A novel MSA35 self-sufficient CYP505 is differentially expressed in antagonistic and pathogenic F. oxysporum. Its expression is induced by the host plant lettuce in both pathogenesis and antagonism during the early phase of the interaction, while it is silenced during the late phase only in antagonistic Fusarium. Mass-spectrometry investigations proved that CYP505A1 mono-hydroxylates lauric, palmitic and stearic acids.

Conclusions: The ability of CYP505A1 to oxidize fatty acids present in the cortical cell membranes together with its differential expression in its Fusarium antagonistic form point out to the possibility that this enzyme is associated with Fusarium pathogenicity in lettuce.

General Significance: The CYP505 clan is present in pathogenic fungal phyla, making CYP505A1 enzyme a putative candidate as a new target for the development of novel antifungal molecules.
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http://dx.doi.org/10.1016/j.bbapap.2019.140268DOI Listing
January 2020

Aspergillus fumigatus population dynamics and sensitivity to demethylation inhibitor fungicides in whole-crop corn, high moisture corn and wet grain corn silages.

Pest Manag Sci 2020 Feb 30;76(2):685-694. Epub 2019 Aug 30.

AGROINNOVA - Centre of Competence for the Innovation in the Agro-environmental Sector, Università di Torino, Grugliasco, Italy.

Background: Aspergillus fumigatus, the causal agent of aspergillosis in humans, is commonly present as a saprophyte in various organic substrates, such as spoiled silages. Aspergillosis is generally combated with demethylation inhibitor (DMI) fungicides, but the recent appearance of resistant medical and environmental strains made current treatment strategies less reliable. The goal of this study was to determine the evolution of A. fumigatus populations during the ensiling process of whole-crop corn, high moisture corn and wet grain corn, and to monitor the sensitivity of isolates from treated and untreated fields to one medical and one agricultural DMI fungicide.

Results: A. fumigatus was isolated from fresh forage at harvest at rather low concentrations (10  cfu g ). The low frequency lingered during the silage process (at 60 and 160 days), whereas it significantly increased during air exposure (at 7 and 14 days of air exposure). Field treatment of corn with a mixture of prothioconazole and tebuconazole did not affect the sensitivity of A. fumigatus isolates. One of 29 isolates from the untreated plot was resistant to voriconazole. A unique amino acid substitution (E427K) was detected in the cyp51A gene of 10 of 12 sequenced isolates, but was not associated with DMI resistance.

Conclusion: A. fumigatus significantly increased during aerobic deterioration of ensilaged corn after silo opening, compared with the low presence in fresh corn and during ensiling. Field treatment of corn with DMI fungicides did not affect the sensitivity of A. fumigatus isolates collected from fresh and ensiled corn. © 2019 Society of Chemical Industry.
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http://dx.doi.org/10.1002/ps.5566DOI Listing
February 2020

Ready-to-Eat Salad Crops: A Plant Pathogen's Heaven.

Plant Dis 2019 Sep 25;103(9):2153-2170. Epub 2019 Jul 25.

Centre of Competence for the Agro-Environmental Sector (AGROINNOVA), University of Torino. Largo Paolo Braccini 2, 10095 Grugliasco, Italy.

The ready-to-eat salad sector, also called fresh-cut or bagged salads, is a fast-growing segment of the fresh-food industry. The dynamism and specialization of this sector, together with the lack of adequate crop rotation, the globalization of the seed market, and climate change, are the main causes of the development of many new diseases that cause severe production losses. Newly detected diseases of the most important crops grown (lettuce, wild and cultivated rocket, lamb's lettuce, chicory, endive, basil, spinach, and Swiss chard) are critically discussed. The management of these diseases represents a formidable challenge, since few fungicides are registered on these minor-use crops. An interesting feature of the ready-to-eat salad sector is that most crops are grown under protection, often in soilless systems, which provide an environment helpful to the implementation of innovative control methods. Current trends in disease management are discussed, with special focus on the most sustainable practices.
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http://dx.doi.org/10.1094/PDIS-03-19-0472-FEDOI Listing
September 2019

Rapid Detection of and on Peach and Nectarine using Loop-Mediated Isothermal Amplification.

Plant Dis 2019 Sep 12;103(9):2305-2314. Epub 2019 Jul 12.

Centre of Competence for the Innovation in the Agro-environmental Sector-AGROINNOVA, University of Turin, via Paolo Braccini 2, I-10095 Grugliasco, TO, Italy.

and are two causal agents of brown rot, one of the most important diseases in stone fruit. Two species cause blight on blossoms and twigs and brown rot on fruit in pre- and postharvest. Both species are distributed worldwide in North and South America, Australia, and Japan. In Europe, is endemic, while was introduced in 2001 and it is now widespread in several countries. Currently, both species coexist in European stone fruit orchards. spp. overwinter in cankers and mummified fruit. Mummy monitoring during winter permits growers to understand which species of will be prevalent in an orchard during the following season, permitting planning of an appropriate crop protection. Traditionally, the identification has been carried out using morphological features and even with polymerase chain reaction (PCR)-based assays that requires time and well-equipped laboratories. In this study, two isothermal-based methods were designed to identify these pathogens in a faster way than using traditional methods. The loop-mediated amplification (LAMP) assays were validated on some isolates of spp. coming from the mummy monitoring according to the international European and Mediterranean Plant Protection Organization standard (PM7/98), taking into account specificity, sensitivity, repeatability, and reproducibility. The sensitivity of both assays was checked by monitoring (at different time points) two nectarine varieties artificially inoculated and stored at two different temperatures. The reliability of both LAMP assays against the quantification of the inoculum was compared with previously published quantitative PCR assays. Both LAMP methods were able to detect a low number of cells. These LAMP methods could be a useful tool for monitoring brown rot causal agents in the field and during postharvest.
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http://dx.doi.org/10.1094/PDIS-01-19-0035-REDOI Listing
September 2019

Priming xylem for stress recovery depends on coordinated activity of sugar metabolic pathways and changes in xylem sap pH.

Plant Cell Environ 2019 06 8;42(6):1775-1787. Epub 2019 Mar 8.

Department of Agriculture, Forest and Food Sciences (DISAFA), University of Turin, Grugliasco, Italy.

Some plant species are capable of significant reduction of xylem embolism during recovery from drought despite stem water potential remains negative. However, the functional biology underlying this process is elusive. We subjected poplar trees to drought stress followed by a period of recovery. Water potential, hydraulic conductivity, gas exchange, xylem sap pH, and carbohydrate content in sap and woody stems were monitored in combination with an analysis of carbohydrate metabolism, enzyme activity, and expression of genes involved in sugar metabolic and transport pathways. Drought resulted in an alteration of differential partitioning between starch and soluble sugars. Upon stress, an increase in the starch degradation rate and the overexpression of sugar symporter genes promoted the efflux of disaccharides (mostly maltose and sucrose) to the apoplast. In turn, the efflux activity of the sugar-proton cotransporters caused a drop in xylem pH. The newly acidic environment induced the activity of apoplastic invertases leading to the accumulation of monosaccharides in the apoplast, thus providing the main osmoticum necessary for recovery. During drought and recovery, a complex network of coordinated molecular and biochemical signals was activated at the interface between xylem and parenchyma cells that appeared to prime the xylem for hydraulic recovery.
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http://dx.doi.org/10.1111/pce.13533DOI Listing
June 2019

Development of Loop-Mediated Isothermal Amplification Assays for the Detection of Seedborne Fungal Pathogens Fusarium fujikuroi and Magnaporthe oryzae in Rice Seed.

Plant Dis 2018 Aug 30;102(8):1549-1558. Epub 2018 May 30.

FERA, and IAFRI, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom.

Bakanae disease (caused by Fusarium fujikuroi) and rice blast (caused by Magnaporthe oryzae) are two of the most important seedborne pathogens of rice. The detection of both pathogens in rice seed is necessary to maintain high quality standards and avoid production losses. Currently, blotter tests are used followed by morphological identification of the developing pathogens to provide an incidence of infection in seed lots. Two loop-mediated isothermal amplification assays were developed with primers designed to target the elongation factor 1-α sequence of F. fujikuroi and the calmodulin sequence of M. oryzae. The specificity, sensitivity, selectivity, repeatability, and reproducibility for each assay was assessed in line with the international validation standard published by the European and Mediterranean Plant Protection Organization (PM7/98). The results showed a limit of detection of 100 to 999 fg of DNA of F. fujikuroi and 10 to 99 pg of M. oryzae DNA. When combined with a commercial DNA extraction kit, the assays were demonstrated to be effective for use in detection of the pathogens in commercial batches of infected rice seed of different cultivars, giving results equivalent to the blotter method, thus demonstrating the reliability of the method for the surveillance of F. fujikuroi and M. oryzae in seed-testing laboratories.
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http://dx.doi.org/10.1094/PDIS-08-17-1307-REDOI Listing
August 2018

Emergence of Leaf Spot Disease on Leafy Vegetable and Ornamental Crops Caused by and Species.

Phytopathology 2019 Jun 24;109(6):1053-1061. Epub 2019 Apr 24.

1 Centre of Competence for the Innovation in the Agro-environmental Sector (AGROINNOVA), Università di Torino, 10095 Grugliasco, Torino, Italy.

The genera and have been established from the former genus and they generally comprise common soil-inhabiting and saprophytic fungi. Within these genera, only two fungi have been recognized as phytopathogenic thus far: and , both of which cause necrotic leaf spots and plant collapse. Severe leaf necrosis and plant decay have been observed in Northern and Southern Italy on leafy vegetable crops. Thirty-six strains of and -like fungi were isolated from affected plants belonging to eight different species. Based on morphological characteristics, 19 strains were assigned to , whereas the remaining strains, which mostly resembled like fungi, could not be identified precisely. Molecular characterization of six loci (internal transcribed spacer [ITS], β-tubulin [], calmodulin [], translation elongation factor 1-alpha [], large subunit ribosomal RNA [LSU], and mitochondrial ATP 6synthase 6 []) of the 36 new isolates and three previously ITS-characterized isolates assigned all strains to four species: , , , and Single and concatenated phylogenetic analyses were conducted, and they clearly distinguished the isolated fungi into four different groups. , , , and were able to induce leaf necrosis singly, and they were confirmed to be the causal agents of the leaf spot disease through pathogenicity assays. The involvement of fungi previously considered saprophytic (i.e., and ) in the development of plant disease for the first time deserves particular attention because of the possibility of their transmission by seeds and the limited knowledge of their management with chemicals.
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http://dx.doi.org/10.1094/PHYTO-10-18-0396-RDOI Listing
June 2019

Increase in aflatoxins due to Aspergillus section Flavi multiplication during the aerobic deterioration of corn silage treated with different bacteria inocula.

J Dairy Sci 2019 Feb 24;102(2):1176-1193. Epub 2018 Dec 24.

Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, Largo Braccini 2, 10095 Grugliasco (Turin), Italy. Electronic address:

The growth of Aspergillus flavus and the production of aflatoxins (AF) during the aerobic deterioration of corn silage represent a problem for animal and human health. This experiment was conducted to evaluate whether the presence of A. flavus and AF production originate from the field or additional AF are produced during the fermentation phase or during aerobic deterioration of corn silage. The trial was carried out in northern Italy on corn at a dry matter (DM) level of 34%. The fresh herbage was either not treated (C) or treated with a Lactobacillus buchneri (LB) NCIMB 40788 [(at 3 × 10 cfu/g of fresh matter (FM)], Lactobacillus hilgardii (LH) CNCM I-4785 (at 3 × 10 cfu/g of FM), or their combination (LB+LH; at 1.5 × 10 cfu/g of FM of each strain) ensiled in 20-L silos and opened after 250 d of ensiling. After silo opening, the aerobic stability was evaluated and samples were taken after 7 and 14 d of air exposure. The pre-ensiled material, the silages at silo opening, and the aerobically exposed silages were analyzed for DM content, fermentative profiles, microbial count, nutritive characteristics, DM losses, and AFB, AFB, AFG, and AFG contents. Furthermore, a subsample of colonies with macromorphological features of Aspergillus section Flavi was selected for AF gene pattern characterization and in vitro AF production. The presence of A. flavus was below the detection limit (<1.00 log cfu/g) in the fresh forage before ensiling, whereas it was found in 1 out of 16 silage samples at silo opening at a level of 1.24 log cfu/g. The AF were found in both the fresh forage and at opening in all the samples, with a predominance of AFB (mean value of 1.71 μg/kg of DM). The inoculation of lactic acid bacteria determined a reduction in the lactic-to-acetic ratio compared with the control. A larger amount of acetic acid resulted in a lower yeast count and higher aerobic stability in the treated silages than in the control ones. At the beginning of aerobic deterioration, the yeasts increased to over 5 log cfu/g, whereas the molds were close to the value observed at silo opening. When the inhibiting conditions were depleted (pH and temperature higher than 5 and 35°C, respectively), both the total molds and A. flavus reached higher values than 8.00 and 4.00 log cfu/g, respectively, thus determining the ex novo production of AFB during aerobic deterioration, regardless of treatments. The analysis of gene pattern showed that 64% of the selected colonies of A. flavus showed the presence of all 4 AF gene patterns, and 43% of the selected colonies were able to produce AF in vitro. During air exposure, after 1,000°C·h have been cumulated, starch content decreased (below 10% DM) and concentration of neutral detergent fiber, acid detergent fiber, hemicelluloses, crude protein, and ash increased. The inoculation with LB and LB+LH increased the aerobic stability of the silages and delayed the onset of aerobic microbial degradation, which in turn indirectly reduced the risk of A. flavus outgrowth and AFB production after silage opening.
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http://dx.doi.org/10.3168/jds.2018-15468DOI Listing
February 2019

Chestnut Drying Is Critical in Determining Growth and Aflatoxin Contamination.

Toxins (Basel) 2018 12 11;10(12). Epub 2018 Dec 11.

DISAFA-Dipartimento di Scienze Agrarie, Forestali ed Alimentari, Università degli Studi di Torino, Largo P. Braccini 2, 10095 Grugliasco, Italy.

Chestnut drying is used to prevent postharvest losses and microorganism contamination during storage. Several studies reported the contamination by aflatoxins (AFs) produced by spp. in chestnuts. The effect of drying temperatures (from 30 to 50 °C) was evaluated on the growth of and the production of aflatoxins in chestnuts. The influence of the treatment on the proximate composition, the total phenol content and antioxidant activity of chestnuts was considered. Fungal colonization was observed on the nuts dried at 30, 35, and 40 °C; the incidence was lower at 40 °C. The highest concentrations of AFB₁ and AFB₂ were produced at 40 °C. No aflatoxins were detected at 45 or 50 °C. At 40 °C was under suboptimal conditions for growth ( 0.78), but the fungus was able to synthesize aflatoxins. As the temperatures applied increased, the total phenol content increased, while the antioxidant activity decreased. A drying treatment at 45 °C for seven days ( 0.64) could be a promising method to effectively control both the growth of aflatoxigenic fungi and the production of aflatoxins. This study provides preliminary data useful to improve the current drying conditions used in chestnut mills, to reduce both fungal growth and aflatoxin production.
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http://dx.doi.org/10.3390/toxins10120530DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6316821PMC
December 2018

Several species of Penicillium isolated from chestnut flour processing are pathogenic on fresh chestnuts and produce mycotoxins.

Food Microbiol 2018 Dec 3;76:396-404. Epub 2018 Jul 3.

DISAFA - Dipartimento di Scienze Agrarie, Forestali ed Alimentari, Università Degli Studi di Torino, Largo P. Braccini 2, 10095 Grugliasco (TO), Italy; Centro di Competenza per l'Innovazione in Campo Agro-ambientale (AGROINNOVA), Università Degli Studi di Torino, Largo P. Braccini 2, 10095 Grugliasco (TO), Italy. Electronic address:

A collection of 124 isolates of Penicillium spp. was created by monitoring fresh chestnuts, dried chestnuts, chestnut granulates, chestnut flour and indoor chestnut mills. Sequencing of the ITS region, β-tubulin and calmodulin, macro-morphology and secondary metabolite production made it possible to determine 20 species of Penicillium. P. bialowiezense was dominant in the fresh chestnuts, while P. crustosum was more frequent in the other sources. A pathogenicity test on chestnut showed that around 70% of the isolates were virulent. P. corylophilum and P. yezoense were not pathogenic, while the other 18 species had at least one virulent isolate. P. expansum and P. crustosum were the most virulent. The isolates were characterized to establish their ability to produce 14 toxic metabolites in vivo: 59% were able to produce at least one mycotoxin. P. expansum was able to produce patulin, chaetoglobosin A and roquefortine, while P. bialowiezense produced C. Mycophenolic acid. Cyclopenins and viridicatins were produced by most of the P. crustosum, P. polonicum, P. solitum and P. discolour isolates. Some of the P. crustosum isolates were also able to produce roquefortine C or penitrem A. Information about the occurrence of Penicillium spp. and their mycotoxins will help producers to set up management procedures that can help to control the fungal growth and the mycotoxin production of chestnuts.
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http://dx.doi.org/10.1016/j.fm.2018.07.003DOI Listing
December 2018

Combined Effect of CO and Temperature on Wheat Powdery Mildew Development.

Plant Pathol J 2018 Aug 1;34(4):316-326. Epub 2018 Aug 1.

AGROINNOVA - Centre of Competence for the Innovation in the Agro-environmental Sector, Università di Torino, 10095 Grugliasco (TO), Italy.

The effect of simulated climate changes by applying different temperatures and CO levels was investigated in the f. sp. /wheat pathosystem. Healthy and inoculated plants were exposed in single phytotrons to six CO+temperature combinations: (1) 450 ppm CO/18-22°C (ambient CO and low temperature), (2) 850 ppm CO/18-22°C (elevated CO and low temperature), (3) 450 ppm CO/22-26°C (ambient CO and medium temperature), (4) 850 ppm CO/22-26°C (elevated CO and medium temperature), (5) 450 ppm CO/26-30°C (ambient CO and high temperature), and (6) 850 ppm CO/26-30°C (elevated CO and high temperature). Powdery mildew disease index, fungal DNA quantity, plant death incidence, plant expression of pathogenesis-related () genes, plant growth parameters, carbohydrate and chlorophyll content were evaluated. Both CO and temperature, and their interaction significantly influenced powdery mildew development. The most advantageous conditions for the progress of powdery mildew on wheat were low temperature and ambient CO. High temperatures inhibited pathogen growth independent of CO conditions, and no typical powdery mildew symptoms were observed. Elevated CO did not stimulate powdery mildew development, but was detrimental for plant vitality. Similar abundance of three transcripts was found, and the level of their expression was different between six phytotron conditions. Real time PCR quantification of was in line with the disease index results, but this technique succeeded to detect the pathogen also in asymptomatic plants. Overall, future global warming scenarios may limit the development of powdery mildew on wheat in Mediterranean area, unless the pathogen will adapt to higher temperatures.
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http://dx.doi.org/10.5423/PPJ.OA.11.2017.0226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6097819PMC
August 2018

Molecular characterization and sensitivity to demethylation inhibitor fungicides of Aspergillus fumigatus from orange-based compost.

PLoS One 2018 12;13(7):e0200569. Epub 2018 Jul 12.

AGROINNOVA-Centre of Competence for the Innovation in the Agro-Environmental Sector, Turin University, Largo P. Braccini 2, Grugliasco, Turin, Italy.

Aspergillus fumigatus, the causal agent of human aspergilloses, is known to be non-pathogenic in plants. It is present as saprophyte in different types of organic matter and develops rapidly during the high-temperature phase of the composting process. Aspergilloses are treated with demethylation inhibitor (DMI) fungicides and resistant isolates have been recently reported. The present study aims to estimate the abundance, genetic diversity and DMI sensitivity of A. fumigatus during the composting process of orange fruits. Composting of orange fruits resulted in a 100-fold increase in A. fumigatus frequency already after 1 week, demonstrating that the degradation of orange fruits favoured the growth of A. fumigatus in compost. Most of A. fumigatus isolates belonged to mating type 2, including those initially isolated from the orange peel, whereas mating type 1 evolved towards the end of the composting process. None of the A. fumigatus isolates expressed simultaneously both mating types. The 52 investigated isolates exhibited moderate SSR polymorphisms by formation of one major (47 isolates) and one minor cluster (5 isolates). The latter included mating type 1 isolates from the last sampling and the DMI-resistant reference strains. Only few isolates showed cyp51A polymorphisms but were sensitive to DMIs as all the other isolates. None of the A. fumigatus isolates owned any of the mutations associated with DMI resistance. This study documents a high reproduction rate of A. fumigatus during the composting process of orange fruits, requesting specific safety precautions in compost handling. Furthermore, azole residue concentrations in orange-based compost were not sufficient to select A. fumigatus resistant genotypes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0200569PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6042770PMC
January 2019

Microbiological Parameters in the Primary Production of Berries: A Pilot Study.

Foods 2018 Jul 5;7(7). Epub 2018 Jul 5.

Food Control and Production Hygiene Unit, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, via Bologna 148, 10154 Turin, Italy.

The primary production of fresh soft fruits was considered to be a suspected critical point for the contamination of frozen berries that were responsible for the large 2013⁻2014 Hepatitis A virus (HAV) outbreak in Europe. In this study, an Italian berries’ production area was studied for its agro-technical characteristics, and the fresh fruits were analyzed for the presence of enteric viruses (HAV and Norovirus (NoV) genogroup I and genogroup II (GGI and GGII)), the enumeration of hygienic quality parameters, and the prevalence of bacterial pathogens. A total of 50 producers were sampled, who specialized in the exclusive or shared cultivation of berries. was detected in two blackberry samples, whereas HAV and Norovirus were not detected. The samples were negative for spp., , and Shiga toxin-producing (STEC). The farms’ attributes were not associated with positive samples, apart from the presence of and the aerobic mesophilic bacteria for blackberry that were statistically correlated. In blueberries, the high aerobic mesophilic count could likely be associated with the resistance of the outer layer to handling. However, the two pathogens ( spp. and STEC) and the targeted viruses (HAV, NoV GGI and GGII) were not detected, highlighting the low risk of foodborne pathogens and viral contamination at the primary production stage of the berry food chain in the area considered in this pilot study.
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http://dx.doi.org/10.3390/foods7070105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6069088PMC
July 2018
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