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First Report of Choanephora cucurbitarum on Crotalaria spectabilis : A Highly Aggressive Pathogen Causing a Flower and Stem Blight in Brazil
2018; American Phytopathological Society; Volume: 102; Issue: 7 Linguagem: Inglês
10.1094/pdis-10-17-1610-pdn
ISSN1943-7692
AutoresRafael Ferreira Alfenas, Solange Maria Bonaldo, R. A. S. Fernandes, Mário Roberto Nogueira Colares,
Tópico(s)Plant Pathogenic Bacteria Studies
ResumoHomePlant DiseaseVol. 102, No. 7First Report of Choanephora cucurbitarum on Crotalaria spectabilis: A Highly Aggressive Pathogen Causing a Flower and Stem Blight in Brazil PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Choanephora cucurbitarum on Crotalaria spectabilis: A Highly Aggressive Pathogen Causing a Flower and Stem Blight in BrazilR. F. Alfenas, S. M. Bonaldo, R. A. S. Fernandes, and M. R. N. ColaresR. F. Alfenas†Corresponding author: R. F. Alfenas; E-mail: E-mail Address: ralfenas@ufmt.brSearch for more papers by this author, S. M. Bonaldohttp://orcid.org/0000-0002-2240-2700Search for more papers by this author, R. A. S. FernandesSearch for more papers by this author, and M. R. N. ColaresSearch for more papers by this authorAffiliationsAuthors and Affiliations R. F. Alfenas † , Faculdade de Engenharia Florestal/PPGCFA, Universidade Federal de Mato Grosso, Cuiabá, 78060900, MT, Brazil S. M. Bonaldo , Instituto de Ciências Agrárias e Ambientais/PPGCAM, Universidade Federal de Mato Grosso, Sinop, 78550728, MT, Brazil R. A. S. Fernandes , Departamento de Fitopatologia, Universidade de Brasília, 70910900, DF, Brazil M. R. N. Colares , Departamento de Fitopatologia, Universidade Federal de Lavras, 37200000, MG, Brazil. Published Online:22 May 2018https://doi.org/10.1094/PDIS-10-17-1610-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Crotalaria spectabilis Roth is a herbaceous plant, native to tropical Asia, that was introduced in Brazil as a fodder plant, for green manure, nitrogen fixation, and nematode control. In May 2014, 90% of C. spectabilis plants grown on more than 1,000 ha were severely infected with flower and stem blight disease in Tapaborã, Mato Grosso, Brazil. The symptoms started on flowers, causing blight and water-soaked lesions, spreading to the stem causing grayish lesions, followed by rapidly rotting. From infected tissues, a fungus that produced cottony, white mycelium and black spore masses was consistently isolated on potato dextrose agar. The mycelium was nonseptate and hyaline. Sporangiola were ellipsoid to ovoid, brown to reddish-brown, striated, measuring 11 to 20 × 7 to 13 µm. Secondary vesicles were light brown ranging from 15 to 26 µm in diameter, and mature sporangia were brown to dark brown, globose to ellipsoid, and 64 to 69 × 56 to 59 µm. The internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) sequences was generated using ITS1 and ITS4 primers and the sequences were deposited in GenBank under accession numbers MF942131 (isolate GFP023) and MF942130 (isolate GFP024). The generated sequences had 100% nucleotide identity with corresponding sequences of Choanephora infundibulifera f. cucurbitarum (KJ461159, KM200034, JN943006). Neighbor-joining phylogenetic analysis was performed using Tamura-Nei model in MEGA 7 software and revealed that the isolates GFP024 and GFP023 collected in Mato Grosso clustered in a clade of Choanephora cucurbitarum supported by a high bootstrap value. The fungus was identified as C. cucurbitarum (Berk. & Ravenel) Thaxt. (syn. C. infundibulifera f. cucurbitarum) based on morphological features (Kirk 1984) and molecular analysis. For pathogenicity testing, five 100-day-old flowering plants were spray-inoculated with a suspension at 2 × 104 spore ml−1 and then covered with polythene bags for 48 h under greenhouse conditions. Five plants sprayed with distilled water were used as control. Four days after inoculation, typical symptoms of the disease were observed, similar to those found under natural conditions. The negative impact of this disease on seed production was also observed, since noninoculated plants produced 6 g of seeds/plant and inoculated plants produced only 0.24 g of seeds/plant. Koch’s postulates were proven by reisolating the fungal pathogen in a pure culture. The results showed that C. cucurbitarum is the causal agent of the flower and stem blight on C. spectabilis in Mato Grosso, Brazil. Moreover, in the blotter test, C. cucurbitarum was detected at 2% incidence on C. spectabilis seeds. C. cucurbitarum has been reported on C. spectabilis in India, Sierra Leone, and Trinidad and Tobago (Farr and Rossman 2017) and in Brazil, this fungus has been reported on Brassica oleracea L. var. capitata L., Capsicum annuum L., Cucurbita sp. L., and Vigna unguiculata (L.) Walp. (Mendes and Urben 2017). However, this is the first report of C. cucurbitarum on C. spectabilis plantation in Brazil.References:Farr, D. F., and Rossman, A. Y. 2017. Fungal Databases, U.S. National Fungus Collections, ARS, USDA. Retrieved October 13, 2017, from https://nt.ars-grin.gov/fungaldatabases/ Google ScholarKirk, P. M. 1984. Mycol Pap. 152:1. Google ScholarMendes, M. A. S., and Urben, A. F. 2017. Fungos relatados em plantas no Brasil, Retrieved November 11, 2017, from http://pragawall.cenargen.embrapa.br/aiqweb/michtml/fgbanco01.asp Google ScholarFunding: Fundação de Amparo à Pesquisa do Estado de Mato Grosso (224618/2015), PROCEV/UFMT.DetailsFiguresLiterature CitedRelated Vol. 102, No. 7 July 2018SubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Issue Date: 27 Jun 2018Published: 22 May 2018First Look: 1 Feb 2018Accepted: 31 Jan 2018 Page: 1456 Information© 2018 The American Phytopathological SocietyFundingPROCEV/UFMTFundação de Amparo à Pesquisa do Estado de Mato GrossoGrant/Award Number: 224618/2015Cited byChoanephora cucurbitarum (Choanephora fruit rot)CABI Compendium, Vol. CABI CompendiumFirst Report of Choanephora cucurbitarum Causing Leaf Wilt, Flower Rot, and Stem Necrosis on Crotalaria brevifloraG. S. Oliveira, R. A. S. Fernandes, D. B. Pinho, and S. M. Bonaldo2 April 2021 | Plant Disease, Vol. 105, No. 5
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