In 2018, a disease outbreak was observed on pumpkin (Cucurbita moschata cv. Violina) in the municipality of Reggio Emilia (Northern Italy). Symptoms were observed on leaves and fruits

Babadoost M

Dutta B

Huss H

Kiryukhina RI

English

Altin, Irem

Casoli, Luca

Stefani, Emilio

Archivio istituzionale della ricerca - Università di Modena e Reggio Emilia

 (http://bspp.org.uk/index.php) New Disease Reports(index.php)New Disease Reports (2020) 41, 21. [http://dx.doi.org/10.5197/j.2044-0588.2020.041.021]< Prev(/article.php?id=41020First report of bacterial spot caused byXanthomonas cucurbitae on pumpkin in ItalyI. Altin , L. Casoli  and E. Stefani **emilio.stefani@unimore.itShow affiliationsReceived: 23 Jan 2020; Published: 16 Apr 2020Keywords: bacterial disease, cucurbits, watermelon, XanthomonadaceaeIn 2018, a disease outbreak was observed on pumpkin (Cucurbita moschata cv. Violina) in the municipality ofReggio Emilia (Northern Italy). Symptoms were observed on leaves and fruits. On leaves, chlorotic spotsappeared in July, after a period of rainstorms, later turning necrotic and coalescing (Fig. 1). On fruits, small,brown spots developed (Fig. 2); some necrotic spots became infected by saprophytes and developed rots(Fig. 3). In the affected field, around 90% of fruits were diseased, leading to a total loss of production. Insummer 2019, the disease was again observed in the same and neighbouring municipalities affecting twopumpkin varieties (C. moschata cv. Violina and C. maxima cv. Mantovana), displaying the same symptomsas in the previous year (Fig. 4). Symptoms were also observed on watermelon; small necrotic spotsdeveloped on leaves, only rarely confluent in large necrotic areas (Fig. 5) whereas, on fruits, no symptomwas noted.Isolation from symptomatic tissue was attempted on glucose yeast chalk agar medium. Bright yellow andmucoid colonies, with entire margins, developed after 48-60 hours at 28°C. Individual colonies were furtherpurified for identification. Pathogenicity of isolates was confirmed on young pumpkin plants (C. moschata andC. maxima, 4 to 6 true leaves) by spraying a bacterial suspension (10  cfu/ml) on the canopy; inoculatedplants were then kept in a glasshouse and observed for symptom development for up to three weeks. Re-isolated bacteria were identical to the original strains as determined by rep-PCR, thereby fulfilling Koch'spostulates. Simplex-PCR with Xanthomonas cucurbitae genus-specific primers (RST2/RST3) produced a 1.4kb amplicon, similar to X. cucurbitae, type strain CFBP 2542. Isolate identity was confirmed by sequencing ofthe gyrB, rpoD, fyuA and dnaK housekeeping genes (GenBank Accession Nos.: gyrB: MT110622, rpoD:MT215599, fyuA: MT110623 dnaK, MT227561). BLAST comparison of representative isolates in GenBankshowed 99.76-100% identity with X. cucurbitae strains (ICMP 2299, ICMP 2179, ICMP 4767). Therefore, thepathogenic xanthomonads isolated in the province of Reggio Emilia were identified as Xanthomonascucurbitae.Prior to 1980, a few unconfirmed records of the pathogen were reported in the former Soviet Union(Kiryukhina, 1980). More recently, bacterial spot of pumpkins was reported in India, China and Nepal(Lamichhane et al., 2010). Bacterial spot of pumpkin is also present in other countries, such as the USA,where it may cause up to 90% crop loss in infected fields (Babadoost & Ravanlou, 2012) and in Canada(Trueman et al., 2014). Recently, the cause of leaf spot of pumpkin affecting fields in Styria (Austria) wasattributed to a set of phytopathogenic bacteria, including X. cucurbitae (Huss, 2011), although no officialidentification was completed. This is the first confirmed report of bacterial spot of pumpkin, followed byisolation, identification and characterisation of its causal agent, Xanthomonas cucurbitae, in Italy and Europe.ISSN (International Standard Serial Number) 2044-0588NDRs (/index.php)/scope.php)Submission(/submission.php)Volumes(/volumes.php)Search(/search.php)Editors(/editors.php)BSPP(http://www.bspp.org.uk/) 1  2  17First report of bacterial spot caused by Xanthomonas cucurbitae on p... https://www.ndrs.org.uk/article.php?id=0410211 di 5 20/04/2020, 10:54Figure 1: Yellow to brown and angular spots observed on pumpkin leaves, later coalescing in large, necrotic lesions.The geographical origin of the pathogen is unknown, but its introduction might be connected with theinternational trade of pumpkin seed. Our observation of X. cucurbitae leaf spot on watermelon supports thereport of Dutta et al. (2013). Further research is needed to assess the host range of the Italian isolates of X.cucurbitae amongst cucurbits.+First report of bacterial spot caused by Xanthomonas cucurbitae on p... https://www.ndrs.org.uk/article.php?id=0410212 di 5 20/04/2020, 10:54Figure 2: Circular, water-soaked, sunken spots developing on Cucurbita moschata cv. Violina; spots vary in size andhad a pale-brown and cracked centre.Figure 3: On several fruits, bacterial spots were infected by pectolytic saprophytes, causing large and deep tissue rots.++First report of bacterial spot caused by Xanthomonas cucurbitae on p... https://www.ndrs.org.uk/article.php?id=0410213 di 5 20/04/2020, 10:54Figure 4: Bacterial spot symptoms on fruit of Cucurbita maxima cv. Mantovana.Figure 5: Bacterial spot on leaves of watermelon, Citrullus lanatus cv. Crimson Sweet.Acknowledgements++First report of bacterial spot caused by Xanthomonas cucurbitae on p... https://www.ndrs.org.uk/article.php?id=0410214 di 5 20/04/2020, 10:54Research conducted in the framework of the EU-COST Action CA16107 "EuroXanth: Integrating Science onXanthomonadaceae".ReferencesBabadoost M, Ravanlou A, 2012. Outbreak of bacterial spot (Xanthomonas cucurbitae) in pumpkin fieldsin Illinois. Plant Disease 96, 1222. [http://dx.doi.org/10.1094/PDIS-03-12-0241-PDN (http://dx.doi.org/10.1094/PDIS-03-12-0241-PDN)]1. Dutta B, Gitaitis RD, Lewis KJ, Langston DB, 2013. A new report of Xanthomonas cucurbitae causingbacterial leaf spot of watermelon in Georgia, USA. Plant Disease 94, 556. [http://dx.doi.org/10.1094/PDIS-10-12-0908-PDN (http://dx.doi.org/10.1094/PDIS-10-12-0908-PDN)]2. Huss H, 2011. Krankheiten und Schädlinge im Ölkürbisbau. Der fortschrittliche Landwirt, 3, 30-33.3. Kiryukhina RI, 1980 Diagnostics of Bacterial Diseases of Vegetable Cultures and Measures of TheirControl. Moscow, Russia: Russian Academy of Agricultural Sciences (in Russian).4. Lamichhane JR, Varvaro L, Balestra GM, 2010. Bacterial leaf spot caused by Xanthomonas cucurbitaereported on pumpkin in Nepal. New Disease Reports 22, 20. [http://dx.doi.org/10.5197/j.2044-0588.2010.022.020 (http://dx.doi.org/10.5197/j.2044-0588.2010.022.020)]5. Trueman CL, Roddy E, Goodwin PH, 2014. First report of bacterial spot (Xanthomonas cucurbitae) ofpumpkin in Ontario, Canada. New Disease Reports 30, 8. [http://dx.doi.org/10.5197/j.2044-0588.2014.030.008 (http://dx.doi.org/10.5197/j.2044-0588.2014.030.008)]6. To cite this report: Altin I, Casoli L, Stefani E, 2020. First report of bacterial spot caused by Xanthomonascucurbitae on pumpkin in Italy. New Disease Reports 41, 21. [http://dx.doi.org/10.5197/j.2044-0588.2020.041.021 (http://dx.doi.org/10.5197/j.2044-0588.2020.041.021)]©2020 The AuthorsWebsite: Steve Roberts (http://www.sr-images.co.uk) | Webmanager (mailto:webmanager@ndrs.org.uk) | Disclaimer(/legal.php) | BSPP Home (http://www.bspp.org.uk/) |  (/rss/)©2000-2020 BSPP (/copyright.php)New Disease Reports is an international online peer-reviewed journal published by the British Society for Plant Pathology(BSPP).The British Society for Plant Pathology is a registered charity and a limited company. Charity No. 1071465. Company No.3576579.Registered office: c/o Society of Biology, Charles Darwin House, 12 Roger Street, London, WC1N 2JU, UK.Updated: 16 Apr 2020First report of bacterial spot caused by Xanthomonas cucurbitae on p... https://www.ndrs.org.uk/article.php?id=0410215 di 5 20/04/2020, 10:54

First report of bacterial spot caused by Xanthomonas cucurbitae on pumpkin in Italy

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First report of bacterial spot caused by Xanthomonas cucurbitae

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First report of bacterial spot caused by Xanthomonas cucurbitae on pumpkin in Italy

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