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First Report of Phytophthora Fruit Rot in Apple Caused by Phytophthora syringae During Cold Storage in Maule Region, Chile

2016; American Phytopathological Society; Volume: 100; Issue: 7 Linguagem: Inglês

10.1094/pdis-12-15-1462-pdn

1943-7692

Mauricio Lolas, Janet Contreras, R Vazquez Mendez, Marcela Eugenia da Silva Cáceres, Gonzalo A. Díaz,

Yeasts and Rust Fungi Studies

HomePlant DiseaseVol. 100, No. 7First Report of Phytophthora Fruit Rot in Apple Caused by Phytophthora syringae During Cold Storage in Maule Region, Chile PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Phytophthora Fruit Rot in Apple Caused by Phytophthora syringae During Cold Storage in Maule Region, ChileM. Lolas, J. M. Contreras, R. Méndez, M. Cáceres, and G. A. DíazM. LolasSearch for more papers by this author, J. M. ContrerasSearch for more papers by this author, R. MéndezSearch for more papers by this author, M. CáceresSearch for more papers by this author, and G. A. DíazSearch for more papers by this authorAffiliationsAuthors and Affiliations M. Lolas J. M. Contreras R. Méndez M. Cáceres G. A. Díaz , Laboratorio de Patología Frutal, Facultad de Ciencias Agrarias, Universidad de Talca, Casilla 747-721, Talca, Chile. Published Online:31 Mar 2016https://doi.org/10.1094/PDIS-12-15-1462-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Chile is one of the major exporters of apple worldwide (ODEPA 2015) and the Maule Region (35°25′ S) is the most important apple-production region in Chile, with 22,488 ha. During 2014 and 2015, in two packing houses located at Río Claro, Maule Region, a postharvest rot was observed on ‘Jonagold’ and ‘Pink Lady’ apples after 60 days of cold storage at 0°C with less than 0.1% prevalence. Symptoms consisted of light brown skin discolorations with spongy to firm flesh texture, being the pericarp darker than the advancing zone of infection. To isolate the causal agent, surface-sterilized pieces of rotted tissue were placed onto antibiotic corn meal agar (Latorre et al. 2001). A Phytophthora sp. was consistently isolated after 7 days incubation at 20°C, from 10 and 30 decayed apples in 2014 and 2015, respectively. Hyphal tips were subcultured on 2% PDA to obtain pure cultures. Eight representative Phytophthora isolates examined in detail were homothallic, and catenulate hyphal swellings were observed but no chlamydospores. Sporangia were produced in nonsterile soil extract after several washes with a sterile cold mineral salt solution and incubation at 20°C in the dark. Sporangia were persistent, semipapillate, ovoid to pyriform, with mean dimensions of 25 to 39 × 19 to 25 μm and a length:width ratio of 1.3:1 to 1.6:1. Oospores were plerotic, round and thick walled, and 25 to 30 μm in diameter. On the basis of morphological features, the isolates were identified as Phytophthora syringae (Kleb.) Kleb (Erwin and Ribeiro 1996). To corroborate this identification, genomic rDNA (isolates MZ-PHY-1, MZ-PHY-3, and MZ-PHY-4) was amplified, and then purified and sequenced in Macrogen, South Korea, using internal transcribed spacer (ITS) primers ITS1 and ITS4 (White et al. 1990). The sequences were deposited in GenBank (Accession Nos. KU170701 to KU170703). BLASTn analyses showed 100% homology with P. syringae (AF266803). A pathogenicity test was conducted with two isolates (MZ-PHY-1 and MZ-PHY-3) on mature apples Pink Lady and ‘Granny Smith.’ Twenty fruits of each cultivar were surface disinfested with 75% ethanol for 30 s, a small core was removed with a sterile corker borer (5 mm diameter), and the apples were inoculated with mycelial plugs (5-mm) from 7-day-old cultures. An equal number of apples injured but treated with sterile agar plugs were used as negative controls. The apples were placed into a commercial packing box and incubated at 0°C and 95% RH for 45 days. All inoculated apples developed necrotic lesions similar to the original symptoms, measuring 24.5 to 29.4 mm in diameter for Granny Smith and 11.2 to 15.2 mm for Pink Lady. The negative controls remained healthy. Koch’s postulates were fulfilled by reisolating (100%) P. syringae from only the inoculated apples. Previously, P. syringae was reported to cause apple fruit rot in the USA and the UK (Spotts and Grove 2002). To the best of our knowledge, this is the first report of fruit rot caused by P. syringae in cold stored apples in Chile. Further studies are needed to know the extent of the risk of Phytophthora fruit rot in the Maule Region.References:Erwin, D. C., and Ribeiro, O. K. 1996. Phytophthora Diseases Worldwide. APS Press, St. Paul, MN. Google ScholarLatorre, B., et al. 2001. Plant Dis. 85:603. https://doi.org/10.1094/PDIS.2001.85.6.603 Link, ISI, Google ScholarODEPA. Ministerio de Agricultura, Gobierno de Chile. Retrieved from www.odepa.cl, accessed 17 November 2015. Google ScholarSpotts, R. A., and Grove, G. G. 2002. Plant Dis. 86:693. https://doi.org/10.1094/PDIS.2002.86.6.693B Link, ISI, Google ScholarWhite, T. J., et al. 1990:Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego. Crossref, Google ScholarDetailsFiguresLiterature CitedRelated Vol. 100, No. 7 July 2016SubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Issue Date: 7 Jun 2016Published: 31 Mar 2016First Look: 1 Feb 2016Accepted: 22 Jan 2016 Pages: 1507-1507 Information© 2016 The American Phytopathological SocietyCited byPhytophthora syringae (twig blight of lilac)CABI Compendium, Vol. CABI CompendiumCharacterization and pathogenicity of three Phytophthora spp. recovered from rivers in BulgariaJournal of Phytopathology, Vol. 168, No. 4Identification and characterization of Diplodia mutila, D. seriata, Phacidiopycnis washingtonensis and Phacidium lacerum obtained from apple (Malus x domestica) fruit rot in Maule Region, Chile24 November 2018 | European Journal of Plant Pathology, Vol. 153, No. 4