S. Franco Ortega
University of Turin
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Plant Pathology | 2017
G. Gilardi; S. Franco Ortega; P. C. J. van Rijswick; G. Ortu; Maria Lodovica Gullino; A. Garibaldi
Fusarium oxysporum f. sp. lactucae, the causal agent of the Fusarium wilt of lettuce (Lactuca sativa L.), occurs in most countries in which lettuce is grown and causes serious economic losses. Three races (1, 2, and 3) of the pathogen had previously been identified on the basis of their ability to cause disease on differential lettuce cultivars as well as by means of molecular tools developed to characterize different races of this pathogen. Only race 1 has been detected in Europe so far. In this study, two isolates of Fusarium oxysporum, obtained from lettuce plants grown in the Netherlands showing symptoms of wilt, have been characterized by combining the study of pathogenicity with differential cultivars of lettuce and molecular assays to determine whether the isolates were different from the known races of F. oxysporum f.sp. lactucae. The present study reports the presence of F. oxysporum f. sp. lactucae for the first time in the Netherlands. The causal pathogen has been identified, using the IRAP-SCAR technique, as a new race of F. oxysporum f. sp. lactucae. Specific primers have been designed to identify this new race. This article is protected by copyright. All rights reserved.
Journal of Plant Pathology | 2016
A. Garibaldi; G. Gilardi; S. Franco Ortega; Maria Lodovica Gullino
Liquidambar styraciflua (American sweetgum, Altingiaceae) is a deciduous tree native to warm temperate areas of eastern North America and tropical montane regions of Mexico and Central America. In Italy it is a popular ornamental tree. During summer–fall 2014, a new leaf spot was observed on 30-year-old plants of L. styraciflua, at temperatures ranging between 15 and 26°C and high relative humidity. All of the five plants in a private garden close to Biella (northern Italy) were affected. Seventy to eighty percent of leaves showed necrotic spots, 10 to 60 mm in diameter, with a purple margin, often interesting the margins of the leaves. Colletotrichum sp. was consistently recovered with a frequency of 70% from several isolations from infected leaf tissues carried out on potato dextrose agar (PDA) amended with 25 mg/l of streptomycin sulphate (Bailey and Jeger, 1992). Hyaline, cylindrical, aseptate and thin walled conidia (13.0 to 18.7 x 3.8 to 5.9, average 16.2 x 4.7 μm size) were abundantly produced in acervuli in a gray mycelium on PDA medium. DNA was extracted with E.Z.N.A. Plant DNA Kit (Omega Bio-Tek) and PCR reactions were performed using primers ITS1/ITS4, and primers T1 (O’Donnell and Cigelink, 1997) and βt2b (Glass and Donaldson, 1995). The 499 bp and 725 bp products were sequenced (GenBank accession Nos. KT375326 and KT375325, respectively) and confirmed to correspond to Colletotrichum kahawae. Pathogenicity tests were performed under growth chamber at 24 to 26°C and 12 h photoperiod by spraying L. styraciflua leaves with 1x105 conidia/ml or sterile water covered with plastic bags for 5 days. About 7 to 10 days after inoculation, lesions developed only on inoculated leaves and Colletotrichum sp. was consistently reisolated. This is the first report of Colletotrichum kahawae on American sweetgum in Italy as well as worldwide. Due to the increased number of report of C. kahawae in Italy on species such as olive, mango and cultivated rocket, the adoption of preventative strategies to contain the spread of this pathogen is suggested.
Journal of Plant Pathology | 2016
A. Garibaldi; D. Bertetti; S. Franco Ortega; Maria Lodovica Gullino
Verbascum nigrum “Album” is a perennial plant belonging to the spontaneous flora in Italy appreciated for the lasting white inflorescences. During the summer 2015, several plants of V. nigrum “Album” grown in gardens in the Biella province showed symptoms of a previously unknown powdery mildew. Leaves, stems and florets were covered with white mycelia. Conidiophores had a cylindrical foot cell measuring 94-188×11-15 (average 159×12) μm followed by 2 shorter cells, measuring 15-34×10-14 (average 20×12) μm. Conidia were elliptical to doliform, borne in short chains, measured 25-39×16-23 (average 34×21) μm and germinated apically. The Internal Transcribed Spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 and sequenced (White et al., 1990) (GenBank Accession No. KT953356). The 524 bp amplicon had 100% homology with the sequence of Golovinomyces cichoracearum HQ316555. Pathogenicity was confirmed by spraying a conidial suspension (1.2×105 CFU/ml) onto leaves of three healthy plants of V. nigrum “Album”. Three control plants were treated with sterilised water. Fifteen days after inoculation, symptoms of powdery mildew developed only on inoculated plants. Erysiphe verbasci (Syn.: Golovinomyces verbasci), diffused only on Scrophulariaceae, was reported on V. nigrum in Europe (Braun, 1995). G. cichoracearum, widely diffused on Asteraceae, is reported on V. nigrum for the first time in Italy as well as worldwide.
Journal of Plant Pathology | 2016
A. Garibaldi; D. Bertetti; S. Franco Ortega; Maria Lodovica Gullino
During the summer and autumn 2015, symptoms of an unknown leaf blight were observed on fruit-scented sage (Salvia dorisiana), Labiatae family, cultivated in a private garden located in the Biella province (northern Italy). Brown necrosis with irregular margins developed on both leaf surfaces, on the apexes and along the borders. Sometime, a soft, grey mycelium grew on affected tissues. Fungal colonies isolated from leaves on potato dextrose agar (PDA) were typical of Botrytis cinerea (Ellis, 1971) and produced branched conidiophores and unicellular, ovoid conidia, measuring 7.8-14.5 × 6.4-9.0 (average: 10.8×7.5) μm. The Internal Transcribed Spacer (ITS) region of rDNA extracted from a pure culture was amplified using the primers ITS1/ITS4 (White et al., 1990), and sequenced (GenBank accession No. KU163301). BLAST analysis of the 456 bp amplicon had 100% homology with the sequence of B. cinerea (KR080287). To reproduce the field symptoms, one isolate was inoculated on healthy leaves of three S. dorisiana plants. Five leaves per plant were treated with mycelial disks obtained from a pure fungal culture, while three controls were exposed to sterile PDA. All plants were covered with plastic bags and maintained in a greenhouse at temperatures ranging from 15 to 23°C. Five days post inoculation , the first symptoms developed on inoculated leaves only. B. cinerea was reisolated from affected tissues, while controls remained healthy. This is the first report of B. cinerea on S. dorisiana in Italy, as well as in the world. The economic significance of this disease is limited at present, however its importance may expand due to the increasing use of S. dorisiana as a bedding plant.
Journal of Plant Pathology | 2016
A. Garibaldi; D. Bertetti; S. Franco Ortega; Maria Lodovica Gullino
During summer and the following autumn 2015, about a hundred plants of Phlox paniculata growing in a garden near Biella (northern Italy) showed symptoms and signs of an unknown powdery mildew. Leaves, stems and inflorescences were covered by a white mycelium that produced hyaline, elliptical conidia measuring 28-35×16-21 (mean: 31×18) μm. Conidia germinated apically with short, rather clavate germ tubes. Fibrosin bodies were absent. Many chasmothecia, 100-162 (mean: 130) μm in size, formed dark patches on all the affected tissues, particularly on the upper leaf surface. Chasmothecia contained 8-15 shortly stalked, 2- spored asci measuring 44-85×24-40 (mean: 62×29) μm. Spores were ellipsoid to subglobose and measured 21-30×14-21 (mean: 25×18) μm. The ITS region of rDNA extracted from fruiting bodies was amplified using the primers ITS1/ITS4 (Altschul et al., 1997) and sequenced (GenBank accession No. KT953357). The 510 bp amplicon had 99% homology with the sequence of Golovinomyces magnicellulatus (AB769441.1), confirming the relationship between G. magnicellulatus and P. paniculata as recently reported in the phylogenetic analysis of the genus Golovinomyces (Takamatsu et al., 2013). In pathogenicity tests, leaves affected by powdery mildew were gently pressed onto three healthy plants of P. paniculata, which were then were maintained at temperatures ranging from 20 to 26°C. Three non-inoculated plants were used as controls. Fifteen days post inoculation, the first symptoms appeared only on inoculated plants. G. magnicellulatus has been reported on P. paniculata in Great Britain (Jones and Baker, 2007). This is the first report of G. magnicellulatus on P. paniculata in Italy.
Journal of Plant Pathology | 2015
A. Garibaldi; D. Bertetti; S. Franco Ortega; Maria Lodovica Gullino
In the autumn of 2014, in a commercial farm at Albenga (northern Italy), a new disease was observed on 5-month-old potted plants of butterfly lavander (Lavandula stoechas). Initial symptoms consisted of stem necrosis, darkening and withering of the leaves followed by wiltinig of the plants. In the presence of high relative humidity, the lesions became covered with a whitish mycelium which produced irregular dark grey sclerotia 2.0-7.5×1.5-4.0 mm in size. From infected stem pieces placed on potato dextrose agar (PDA) whitish fungal colonies developed, which produced sclerotia measuring 0.6-3.0×0.6-2.7 mm. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 and sequenced (GenBank accession No. KP792750). BLAST analysis (Altschul et al., 1997) of the 492 bp amplified sequence showed a 99% homology with the sequence of Sclerotinia sclerotiorum (JX442064). The pathogenicity of one fungal isolate was tested by placing mycelium and sclerotia grown on autoclaved wheat kernels at the base of three healthy plants of L. stoechas. Control plants were inoculated with autoclaved wheat kernels alone. All the plants were covered with plastic bags and maintained at 25±1°C. First symptoms, consisting of stem necrosis and leaf withering, appeared on inoculated plants five days post inoculation Whereas S. sclerotiorum was constantly reisolated from symptomatic plants, controls remained symptomless. To the best of our knowledge, this is the first report of S. sclerotiorum on L. stoechas in Italy as well as worldwide.
Journal of Plant Pathology | 2015
A. Garibaldi; D. Bertetti; G. Gilardi; S. Franco Ortega; Maria Lodovica Gullino
In summer 2014, symptoms of a previously unknown leaf spot were observed on about 100 plants of Rudbeckia fulgida (family Asteraceae) growing in a garden located near Biella (northern Italy). Extensive necrosis was observed on the leaves, starting from the basal ones, then on flowers and, as the time went on, on the stems. Eventually leaves and stems wilted and the plant, in full blooming, died. A fungus with a soft, greenish mycelium was consistently isolated on potato dextrose agar (PDA). DNA was extracted using the Nucleospin Plant kit (Macherey Nagel, Germany) and PCR was carried out using ITS1/ITS4 primers. A 473 bp PCR product was sequenced (GenBank accession No. KP941053) and a BLASTn search (Altschul et al., 1997) assigned the sequence to Alternaria sp. In pathogenicity tests, leaves of three healthy plants of R. fulgida were inoculated by spraying a spore and mycelium suspension, 1×105 CFU/ml, of the fungus grown on PDA. Plants treated only with sterile water served as control. Plants were covered with plastic bags for 5 days and maintained at 20 -25°C. About five days post inoculation, the first lesions developed only on inoculated leaves from which an Alternaria sp. was consistently reisolated. This is the first report of Alternaria sp. on R. fulgida in Italy as well as in the world.
Journal of Plant Pathology | 2015
A. Garibaldi; D. Bertetti; S. Franco Ortega; Maria Lodovica Gullino
In June 2014, in a nursery of the Agroinnova Centre (Torino, northern Italy) and later in a garden near Biella (northern Italy), several 60- to 90-day-old plants of nettle-leaved bellflower (Campanula trachelium) were observed, that showed water-soaked lesions on the stems. Subsequently, the foliage blighted, turned brown, clung to the shoots, and matted on the surrounding plants. Eventually, infected plants died. Rhizoctonia solani was consistently recovered from diseased tissues in pure culture on potato dextrose agar (PDA). One of the fungal isolates was paired with R. solani tester strains. The C. trachelium isolate anastomosed (low fusion frequency) only with the AG 1 strain (ATCC 58946) (Sneh et al., 1991). Mycelium and sclerotia were typical for AG 1-IB. The internal transcribed tpacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4, and sequenced (GenBank accession No. KP792749). BLAST analysis (Altschul et al., 1997) of the 510 bp amplified sequence showed a 100% similarity with the sequence of R. solani KM589032. For pathogenicity tests, one of the isolates was tested by placing mycelial fragments removed from PDA cultures close to 10 healthy of C. trachelium plants, which were then maintained at 22-25°C. The first symptoms, similar to those observed in the nursery, developed 5-7 days post inoculation and R. solani was consistently reisolated from inoculated plants. By contrast, control plants, inoculated with sterile PDA fragments, remained healthy. This is the first report of R. solani on C. trachelium in Italy as well as worldwide.
Journal of Plant Pathology | 2017
A. Garibaldi; D. Bertetti; S. Franco Ortega; P. Pensa; Maria Lodovica Gullino
Plant Disease | 2016
A. Garibaldi; D. Bertetti; P. Pensa; S. Franco Ortega; Maria Lodovica Gullino