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Occurrence of Onion Smut Caused by Urocystis magica in Chile

2020; American Phytopathological Society; Volume: 104; Issue: 11 Linguagem: Inglês

10.1094/pdis-04-20-0847-pdn

1943-7692

Germán Sepúlveda, Mabel Arismendi-Macuer, Steffany Cárdenas-Ninasivincha, Wilson Huanca‐Mamani, B. A. Latorre,

Plant Pathogens and Resistance

HomePlant DiseaseVol. 104, No. 11Occurrence of Onion Smut Caused by Urocystis magica in Chile PreviousNext DISEASE NOTES OPENOpen Access licenseOccurrence of Onion Smut Caused by Urocystis magica in ChileGermán Sepúlveda, Mabel Arismendi-Macuer, Steffany Cárdenas-Ninasivincha, Wilson Huanca-Mamani, and Bernardo A. LatorreGermán Sepúlveda†Corresponding author: G. Sepúlveda; E-mail Address: gsepulve@uta.clhttp://orcid.org/0000-0002-5610-0970Universidad de Tarapacá, Arica, ChileSearch for more papers by this author, Mabel Arismendi-MacuerUniversidad de Tarapacá, Arica, ChileSearch for more papers by this author, Steffany Cárdenas-NinasivinchaUniversidad de Tarapacá, Arica, ChileSearch for more papers by this author, Wilson Huanca-MamaniUniversidad de Tarapacá, Arica, ChileSearch for more papers by this author, and Bernardo A. LatorrePontificia Universidad Católica de Chile, Santiago, ChileSearch for more papers by this author AffiliationsAuthors and Affiliations Germán Sepúlveda1 † Mabel Arismendi-Macuer1 Steffany Cárdenas-Ninasivincha1 Wilson Huanca-Mamani1 Bernardo A. Latorre2 1Universidad de Tarapacá, Arica, Chile 2Pontificia Universidad Católica de Chile, Santiago, Chile Published Online:17 Sep 2020https://doi.org/10.1094/PDIS-04-20-0847-PDNAboutSectionsView articlePDFPDF PlusSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleOnions (Allium cepa L.) are cultivated on approximately 165 ha in the Lluta and Camiña Valleys, Arica, in northern Chile. Recently, 5 to 20% of the onions have been infected by smut at the seedling stage, so it may be an emerging problem in the region. Symptoms develop first on cotyledons and young leaves with the formation of longitudinal white blisters (sori), mean of 3.8 (3 to 5) × 12.9 (10 to 15) mm, that soon turned dark. Rupture of the epidermis covering the sori exposes spore balls and dark dusty masses of teliospores. Infected plants are stunted. In 2017, three samples (Lluta 1 to 3) of infected leaves and stems were collected in Lluta Valley (18°22′08.74″S, 69°54′18.50″W, above 1,100 m), dehydrated, and kept at 20 to 22°C. Spore balls and teliospores (n = 30 per sample) were characterized after small pieces (2 cm in length) of infected samples were rehydrated in boiling 10% lactic acid on a microscope slide. Spore balls were globose to ellipsoid, mean of 31 (22 to 48) × 27 (18 to 34) μm in diameter, composed of one to two teliospores, surrounded by ovoid, light brown sterile cells. Teliospores were globose to ellipsoidal, dark brown, and smooth, mean of 13 (12 to 14.5) × 12.6 (11 to 14) μm. Based on host plant, symptoms, and teliospore morphology, this fungus was identified as Urocystis magica Pass. (= U. cepulae Frost) (Vánky 2012). Genomic DNA was extracted from teliospores of the three isolates. The internal transcribed spacer region (ITS), the D1/D2 domain of the 28S subunit ribosomal DNA, and the translation elongation factor 1-α (TEF-1α) were amplified by PCR using primers ITS4/ITS5 (White et al. 1990), NL-1m/NL-4m (O’Donnell 1993), and TEF1-728F/TEF1-986R (Carbone et al. 1999), respectively. DNA fragments of ITS (660 to 672 bp), 28S (539 to 628 bp), and TEF-1α (917 to 942 bp) were sequenced (Macrogen, Seoul, South Korea) for the first time and deposited at NCBI GenBank under the accession numbers MH380193, MK468896, and MK468897 for ITS; MH380194, MK474615, and MK474616 for 28S; and MN453810, MN453811, and MN453812 for TEF-1α. Onion leaves (n = 20) of cultivar Century (Seminis) at the seedling stage were surface disinfected in 0.1% sodium hypochlorite for 10 min before being sprayed with 0.1 ml per leaf of U. magica teliospores (106/ml) of isolate Lluta 1. An equal number of plants sprayed with sterile distilled water served as a control. All plants were transferred to small pots 24 h after inoculation and maintained at 20 to 25°C. Longitudinal white blisters and dark sori appeared on inoculated leaves 15 days after inoculation. Control leaves remained symptomless. The presence of U. magica was confirmed morphologically, thus fulfilling Koch’s postulates. This study provides the first evidence for the occurrence of onion smut, caused by U. magica, in the Lluta Valley in Chile. Previously, U. cepulae was associated with onion smut in samples collected over 2,900 km south of Lluta Valley (Mujica and Vergara 1980). The occurrence of onion smut could have a significant impact on onion production, particularly when infection begins at the cotyledonal stage. Therefore, mitigation strategies should be applied.The author(s) declare no conflict of interest.References:Carbone, I., and Kohn, L. 1999. Mycologia 91:553. https://doi.org/10.1080/00275514.1999.12061051 Crossref, ISI, Google ScholarMujica, F., and Vergara, C. 1980. Flora Fungosa Chilena, 2nd Ed. Universidad de Chile, Santiago, Chile. Google ScholarO’Donnell, K. 1993. Page 225 in: The Fungal Holomorph: Mitotic, Meiotic and Pleomorphic Speciation in Fungal Systematics. CAB International, Wallingford, U.K. Google ScholarVánky, K. 2012. Smut Fungi of the World. APS Press, St Paul, MN. Google ScholarWhite, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Crossref, Google ScholarThe author(s) declare no conflict of interest.Funding: This study was financed by the Universidad de Tarapacá, major project UTA 9721–18.DetailsFiguresLiterature CitedRelated Vol. 104, No. 11 November 2020SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionPlants of Echinacea purpurea affected by Verticillium dahliae (A. Garibaldi et al.). Photo credit: M. L. Gullino. Spinach plant infected with Stemphylium leaf spot (K. A. Spawton et al.). Photo credit: M. T. McGrath. Metrics Downloaded 578 times Article History Issue Date: 30 Oct 2020Published: 17 Sep 2020First Look: 10 Jun 2020Accepted: 8 Jun 2020 Page: 3060 Information© 2020 The American Phytopathological SocietyFundingUniversidad de TarapacáGrant/Award Number: major project UTA 9721–18Keywordssmut fungionionAtacama DesertThe author(s) declare no conflict of interest.Cited ByDiversity of culturable bacteria isolated from ancestral crops of Arica and Parinacota Region, Atacama Desert2 November 2020 | Antonie van Leeuwenhoek, Vol. 113, No. 12