Portal de Periódicos da CAPES

First Report of Cercospora cf. citrulina Causing Leaf Spot of Ipomoea pes-caprae in China

2020; American Phytopathological Society; Volume: 105; Issue: 4 Linguagem: Inglês

10.1094/pdis-05-20-1081-pdn

1943-7692

Min Li, Meijiao Hu, Z. Y. Gao, Xiaoyu Hong, C. Zhao, Shunxue Zhang,

Fungal Plant Pathogen Control

HomePlant DiseaseVol. 105, No. 4First Report of Cercospora cf. citrulina Causing Leaf Spot of Ipomoea pes-caprae in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Cercospora cf. citrulina Causing Leaf Spot of Ipomoea pes-caprae in ChinaM. Li, M. J. Hu, Z. Y. Gao, X. Y. Hong, C. Zhao, and S. G. ZhangM. Lihttp://orcid.org/0000-0003-4847-2341Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou, 571101, ChinaSearch for more papers by this author, M. J. Hu†Corresponding author: M. J. Hu; E-mail Address: humeijiao320@163.comhttp://orcid.org/0000-0001-8142-1728Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou, 571101, ChinaSearch for more papers by this author, Z. Y. GaoEnvironment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou, 571101, ChinaSearch for more papers by this author, X. Y. HongEnvironment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou, 571101, ChinaSearch for more papers by this author, C. ZhaoSchool of Life and Pharmaceutical Sciences, Hainan University, Haikou, 570228, ChinaSearch for more papers by this author, and S. G. Zhanghttp://orcid.org/0000-0002-8697-3764School of Life and Pharmaceutical Sciences, Hainan University, Haikou, 570228, ChinaSearch for more papers by this author AffiliationsAuthors and Affiliations M. Li1 M. J. Hu1 † Z. Y. Gao1 X. Y. Hong1 C. Zhao2 S. G. Zhang2 1Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs, Haikou, 571101, China 2School of Life and Pharmaceutical Sciences, Hainan University, Haikou, 570228, China Published Online:21 Mar 2021https://doi.org/10.1094/PDIS-05-20-1081-PDNAboutSectionsView articlePDFPDF Plus ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleIpomoea pes-caprae plays an important role in protecting the tropical and subtropical coastal beaches of the world. In 2018, a leaf spot was observed on I. pes-caprae in Xisha islands of China, and 13.2 to 25.8% of leaves were infected. The initial symptoms were small (1- to 3-mm diameter), single, circular, dark gray spots with a light-yellow center on the leaves. The lesions enlarged and were scattered or confluent, distinct and circular, subcircular or irregular, occasionally vein-limited, pale to dark gray-brown, with a narrow dark brown border surrounded by a diffuse yellow margin. Microscopic observations of the spots revealed that caespituli were dark brown and amphigenous but were abundant on the underside of the leaves. Mycelia were internal. Conidiophores were fasciculate, occasionally solitary, pale olivaceous-brown throughout, zero- to three-septate, 27.9 to 115.8 (63.4 ± 22.5) × 3.2 to 5.3 (4.3 ± 0.87) µm (n = 100). Conidial scars were conspicuously thickened. Conidia were solitary, hyaline, filiform, acicular to obclavate, straight to slightly curved, subacute to obtuse at the apex, truncate at the base, multiseptate, 21.0 to 125.5 (60.2 ± 20.1) × 2.0 to 5.0 (3.8 ± 0.83) µm (n = 100). Single-conidium isolates were obtained from representative colonies grown on potato dextrose agar (PDA) incubated at 25°C in the dark. The colonies grew slowly and were dense, white to gray, and flat with aerial mycelium. Mycelia were initially white and then became gray. Conidia were borne on the conidiophores directly. The pure isolate HTW-1 was selected for molecular identification and a pathogenicity test, and it was deposited in Microbiological Culture Collection Center of Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences. The internal transcribed spacer (ITS) region of rDNA, translation elongation factor 1-alpha (tef1), and histone H3 (his3) genes were amplified with ITS1/ITS4, EF-1/EF-2, and CYLH3F/CYLH3R primers, respectively (Groenewald et al. 2013). The obtained sequences of HTW-1 were all deposited in GenBank with accession numbers MT410467 for ITS, MT418903 for tef1, and MT418904 for his3. The ITS, tef1, and his3 genes all showed 100% similarity for ITS (JX143582), tef1 (JX143340), and his3 (JX142602) with Cercospora cf. citrulina (MUCC 588; MAFF 239409) from I. pes-caprae in Japan. Based on the morphological characteristics and molecular identification, the pathogen was identified as C. cf. citrulina (Groenewald et al. 2013). The pathogenicity test was conducted by spraying conidial suspension (1 × 104 conidia/ml) on wounded and unwounded leaves of seedlings of I. pes-caprae in a greenhouse and in sterile vitro condition. The conidial suspension was prepared using conidia from 30-day-old culture grown on PDA at 25°C in the dark. Leaf surfaces of seedlings in the greenhouse were wounded by lightly rubbing with a steel sponge, and detached leaf surfaces were wounded by sterile needles. The treatments were sprayed with conidial suspensions on wounded and unwounded leaf surfaces. The control was sprayed with sterile water. After 8 days, the typical symptoms of spots, which were small, single, circular, and dark gray appeared on the inoculated wounded leaves, whereas the inoculated unwounded leaves and the control leaves were symptomless. The pathogen was only reisolated from the inoculated wounded leaves. The pathogen may infect via wounds. A total of 20 Cercospora and related species were found on Ipomoea spp. (García et al. 1996). C. cf. citrulina has been reported on I. pes-caprae in Japan, although it was unclear if it was a pathogen or saprophyte (Groenewald et al. 2013). To our knowledge, this is the first report of C. cf. citrulina causing leaf spot of I. pes-caprae in China. This disease could threaten the cultivation of I. pes-caprae in China.The author(s) declare no conflict of interest.References:García, C. E., et al. 1996. Fitopatol. Venez. 9:22. Google ScholarGroenewald, J. Z., et al. 2013. Stud. Mycol. 75:115. https://doi.org/10.3114/sim0012 Crossref, ISI, Google ScholarThe author(s) declare no conflict of interest.Funding: This study was supported by Financial Fund of the Ministry of Agriculture and Rural Affairs, P.R. China (NFZX2018).DetailsFiguresLiterature CitedRelated Vol. 105, No. 4 April 2021SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionLeaf symptom of field-grown ‘Hayward’ kiwifruit plant infected with Actinidia virus (L. Zhao et al.). Photo credit: L. Zhao. Leaf spot of Italian ryegrass naturally infected by Alternaria alternata (X. K. Wei et al.). Photo credit: L. H. Xue. Leaf of Ficus carica displaying symptoms of fig mosaic disease (S. Preising et al.). Photo credit: W. L. da Silva. Metrics Downloaded 537 times Article History Issue Date: 21 Apr 2021Published: 21 Mar 2021First Look: 9 Dec 2020Accepted: 6 Dec 2020 Page: 1203 Information© 2021 The American Phytopathological SocietyFundingFinancial Fund of the Ministry of Agriculture and Rural Affairs, P.R. ChinaGrant/Award Number: NFZX2018KeywordsIpomoea pes-capraeCercospora cf. citrulinaleaf spotThe author(s) declare no conflict of interest.PDF download