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First Report of Apple Bull’s-Eye Rot Caused by Neofabraea perennans in Chile

2020; American Phytopathological Society; Volume: 104; Issue: 5 Linguagem: Inglês

10.1094/pdis-12-19-2561-pdn

1943-7692

Felipe González, Camila Salinas, Blancaluz Pinilla, Antonio Castillo,

Plant-Microbe Interactions and Immunity

HomePlant DiseaseVol. 104, No. 5First Report of Apple Bull's-Eye Rot Caused by Neofabraea perennans in Chile PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Apple Bull's-Eye Rot Caused by Neofabraea perennans in ChileFelipe González, Camila Salinas, Blancaluz Pinilla, and Antonio CastilloFelipe GonzálezLaboratorio de Control Biológico y Nanotecnología, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago, Chile, Alameda 3363, 9170022 Estación Central, Santiago, Chile, Camila SalinasAgrolab, Fitopatología, José Domingo Cañas 2914, 7750173 Ñuñoa, Santiago, Chile, Blancaluz PinillaAgrolab, Fitopatología, José Domingo Cañas 2914, 7750173 Ñuñoa, Santiago, Chile, and Antonio Castillo†Corresponding author: A. Castillo; E-mail Address: [email protected]http://orcid.org/0000-0003-0639-6045Laboratorio de Control Biológico y Nanotecnología, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago, Chile, Alameda 3363, 9170022 Estación Central, Santiago, ChileAffiliationsAuthors and Affiliations Felipe González1 Camila Salinas2 Blancaluz Pinilla2 Antonio Castillo1 † 1Laboratorio de Control Biológico y Nanotecnología, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago, Chile, Alameda 3363, 9170022 Estación Central, Santiago, Chile 2Agrolab, Fitopatología, José Domingo Cañas 2914, 7750173 Ñuñoa, Santiago, Chile Published Online:17 Mar 2020https://doi.org/10.1094/PDIS-12-19-2561-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Bull's-eye rot is a postharvest disease that affects apples (Malus domestica) producing slightly concave and/or flattened circular brown necrotic lesions and is caused by several fungal species belonging to the genus Neofabraea, such as N. perennans, N. malicorticis, N. kienholzii (Pešicová et al. 2017; Soto-Alvear et al. 2013), and Phlyctema vagabunda, previously recognized as N. vagabunda (Chen et al. 2016). In Chile, apple is an important crop with a harvested area of 35,937 ha and a production of 1,766,210 tons in 2017. The incidence of bull's-eye rot is variable depending on climate conditions, reaching up to 60%, and has been attributed mainly to P. vagabunda (Soto-Alvear et al. 2013). In July 2018, 'Cripps Pink' apples from Placilla in the O'Higgins region of central Chile were observed with symptoms of the disease, characterized by circular lesions on the fruit surface that were firm, light brown in the center and surrounded by a darker halo (Pešicová et al. 2017). Symptomatic fruit were collected, washed with distilled water, and surface-disinfected with 70% ethanol. A section of diseased tissue was cut from the edge of the lesion and cultured in PDA medium at 20°C for 10 days in darkness. Conidia were isolated and dilutions were made to obtain monosporic isolates. Mycelial colonies were irregular, centrally umbonate, from gray to dark brown, and 5 days after incubation at 20°C, spongy white mycelium was observed. The microconidia were hyaline, ellipsoidal, with guttulae, and size ranged from 3.0 to 6.0 × 1.3 to 1.8 μm (n = 24), characteristics similar to those described for N. perennans (Verkley 1999). To confirm the fungal species, mycelial genomic DNA obtained from cultures grown for 14 days at 20°C was extracted (Al-Samarrai and Schmid 2000). Then, the LSU, tub2, and rpb2 gene regions were amplified by PCR with the specific primers LR0R/LR5, Bt-T2m-Up/Bt-LEV-L01, and RPB2-5F2/RPB2-F5, respectively (Chen et al. 2016). The sequences of the obtained amplicons were deposited in GenBank with the following accession numbers: LSU (MN602456.1), tub2 (MN687908.1), and rpb2 (MN729470.1). BLAST analysis showed 99.65% (850/853), 100% (848/848), and 100% (907/907) nucleotide identity with N. perennans sequences for the loci LSU (KR858879), tub2 (KR866099), and rpb2 (KR859329), respectively. The amplicons sequences were aligned with GenBank sequences in MAFFT V7.0, a homogeneous partition test was performed in PAUP V4.0 and the LSU, tub2, and rpb2 alignments were concatenated, the best nucleotide substitution model was determined with MEGA-X V10.0.5, and a phylogenetic tree was performed with neighbor-joining (NJ), and maximum-parsimony (MP) methods in PAUP V4.0, and maximum-likelihood (ML) in PhyML V3.0 with 1,000 bootstrapping cycles (Bt). The fungal isolate was identified as N. perennans in a clade with Bt values of 72, 100, and 95% obtained using the NJ, MP, and ML methods, respectively (Chen et al. 2016). The fungal strain was named N. perennans GC57 and it will be deposited in the microbial genetic resources bank, INIA, Chillán, Chile. Pathogenicity tests were performed on healthy 'Cripps Pink' apples. A wound was made in the equatorial area with a needle and 20 μl of a suspension 102, 104, 107 conidia/ml was inoculated. Control apples were inoculated with sterile water (Cameldi et al. 2017). Apples were also inoculated under the cuticle with mycelium discs grown for 10 days at 20°C and PDA discs were used as control (Pešicová et al. 2017). Each treatment was performed on three apples and incubated in a humid chamber for 20 days at 20°C in darkness. Fruits inoculated with fungal propagules developed symptoms similar to those observed in the field, then the fungus was isolated and its identity confirmed, satisfying Koch's postulates. The disease was not observed in control apples. To our knowledge, this is the first report of N. perennans causing bull's-eye rot of apple in Chile. The high incidence of this disease, whose etiological agent is active even at 0°C and during storage and/or transit of Chilean fruit to major foreign markets (United States, Europe, and Asia), may result in considerable economic losses; thus, preharvest disease management is strongly recommended.The author(s) declare no conflict of interest.References:Al-Samarrai, T. H., and Schmid, J. 2000. Lett. Appl. Microbiol. 30:53. https://doi.org/10.1046/j.1472-765x.2000.00664.x Crossref, ISI, Google ScholarCameldi, I., et al. 2017. Plant Pathol. 66:1432. https://doi.org/10.1111/ppa.12684 Crossref, ISI, Google ScholarChen, C., et al. 2016. Fungal Biol. 120:1291. https://doi.org/10.1016/j.funbio.2015.09.013 Crossref, ISI, Google ScholarPešicová, K., et al. 2017. Eur. J. Plant Pathol. 147:683. https://doi.org/10.1007/s10658-016-1036-1 Crossref, ISI, Google ScholarSoto-Alvear, S., et al. 2013. Plant Dis. 97:485. https://doi.org/10.1094/PDIS-06-12-0606-RE Link, ISI, Google ScholarVerkley, G. J. M. 1999. Stud. Mycol. 44:1. Google ScholarThe author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 104, No. 5 May 2020SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionSymptoms observed in the field on zucchini plants caused by Fusarium solani f. sp. cucurbitae (A. Pérez-Hernández et al.). Photo credit: J. M. Gómez-Vázquez. Peach tree with excavated root collar (S. B. Miller et al.). Photo credit: G. Schnabel. Metrics Article History Issue Date: 3 May 2020Published: 17 Mar 2020First Look: 22 Jan 2020Accepted: 20 Jan 2020 Page: 1537 Information© 2020 The American Phytopathological SocietyKeywordsNeofabraea perennansapplesfungal pathogen detectionThe author(s) declare no conflict of interest.Cited byAntifungal Activity of Propolis Extracts against Postharvest Pathogen Phlyctema vagabunda29 December 2022 | Agronomy, Vol. 13, No. 1