First Report of Lasiodiplodia theobromae Causing Stem Brown Rot of Loquat in China

HomePlant DiseaseAhead of PrintFirst Report of Lasiodiplodia theobromae Causing Stem Brown Rot of Loquat in China PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Lasiodiplodia theobromae Causing Stem Brown Rot of Loquat in ChinaQ. Kong, S. J. Xing, K. Xie, Z. Q. Jia, Z. L. Li, Y. Liu, C. L. Xue, X. Shi, C. M. Wang, and S. Y. YuanQ. Konghttps://orcid.org/0000-0002-0360-9650College of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, ChinaSearch for more papers by this author, S. J. XingState Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan 650201, ChinaSearch for more papers by this author, K. XieCollege of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, ChinaSearch for more papers by this author, Z. Q. JiaCollege of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, ChinaSearch for more papers by this author, Z. L. LiCollege of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, ChinaSearch for more papers by this author, Y. LiuCollege of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, ChinaSearch for more papers by this author, C. L. XueCollege of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, ChinaSearch for more papers by this author, X. ShiCollege of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, ChinaSearch for more papers by this author, C. M. Wang†Corresponding authors: C. M. Wang; E-mail Address: [email protected], and S. Y. Yuan; E-mail Address: [email protected]https://orcid.org/0000-0002-7942-0352State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan 650201, ChinaSearch for more papers by this author, and S. Y. Yuan†Corresponding authors: C. M. Wang; E-mail Address: [email protected], and S. Y. Yuan; E-mail Address: [email protected]State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan 650201, ChinaSearch for more papers by this authorAffiliationsAuthors and Affiliations Q. Kong1 S. J. Xing2 K. Xie1 Z. Q. Jia1 Z. L. Li1 Y. Liu1 C. L. Xue1 X. Shi1 C. M. Wang2 † S. Y. Yuan2 † 1College of Biological and Agricultural Sciences, Key Laboratory for Research and Utilization of Characteristic Biological Resources in Southern Yunnan, Honghe University, Mengzi, Yunnan 661199, China 2State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan 650201, China Published Online:29 Jun 2023https://doi.org/10.1094/PDIS-08-22-1982-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleLoquat (Rhaphiolepis biabas, heterotypic synonym: Eriobotrya japonica) is an edible and medicinal plant cultivated on 133,000 ha in 2022 in China. A stem brown rot was observed on young and old trees in Mengzi city (23°23′N; 103°23′E), Yunnan Province, southwest China, from October 2014 to September 2021. Incidence was 20% of trees in surrounding plantations and 50% in a 160-tree orchard that was the focus of the survey. Circular brown lesions occurred initially on the stems and gradually covered all the epidermis of the stem, leading to irregular dents in the bark that developed a dark brown powdery appearance. Larger lesions affected vascular tissues, causing trees to wither and die. Diseased tissues were surface disinfected in 5% NaOCl for 3 min, rinsed three times with sterile distilled water, placed on PDA, and incubated in the dark at 28°C. Twenty samples were collected for tissue isolation, and 11 isolates were single spored on water agar. In culture, the colonies on PDA were white to dark gray, velvet, with dense hyphae, diameter 7.64 cm after 5 days. After 18 days, spherical or subglobose pycnidia were developed and semiburied in the medium and their walls were thicker and dark brown, with black particles surrounded by gray-black hyphae. Conidiogenous cells were hyaline, cylindrical, holoblastic, slightly swollen at the base, with a rounded apex. Conidia were initially hyaline and aseptate, elliptic or ovate, becoming dark brown, single septate, and with longitudinal striations along thick walls at maturity. Conidia were 8.0 to 12.2 × 3.8 to 6.1 μm (n = 50). The morphological characteristics of 11 isolates were consistent with the description of Lasiodiplodia theobromae (Alves et al. 2008). This was further confirmed by sequencing the internal transcribed spacer (ITS), β-tubulin, and partial translation elongation factor-1α (TEF-1α) (Carbone and Kohn 1999; Glass and Donaldson 1995; White et al. 1990). Isolate LSB-1 was used for DNA sequence analysis. Based on BLASTn analysis, ITS sequences (OM617921) had 98.3% similarity with L. theobromae CBS164.96 (accession AY640255), CBS124.13 (accession DQ458890), CAA006 (DQ458891), and CBS111530 (EF622074); β-tubulin sequences (OM643838) had 99.1% similarity with L. theobromae accession EU673110, and TEF-1α (OM643839) had 99.0% identity with L. theobromae accession EF622054. LSB-1 clustered in a clade with other L. theobromae. Pathogenicity of LSB-1, LSB-2, and LSB-3 was tested by inoculating stems of 1-year-old seedlings in pots. The epidermis at the inoculation site, 15 to 20 cm below the crown, was wiped with a 75% alcohol cotton ball, washed three times with sterile water, and punctured (5-mm diameter) with a sterile inoculation needle. A 5-mm block of each isolate cultured on PDA for 7 days was attached to the inoculation site. Controls were inoculated with sterile PDA. The inoculation area was covered with polyethylene film. All plants were kept in a controlled greenhouse at 27°C, 80% relative humidity, and natural daylight, and watered weekly. Each treatment was repeated three times. Eight days after inoculation, all diseased plants had dark brown discoloration at the point of inoculation with the bark at the inoculation site gradually rising over time. Thirty days after inoculation, all inoculated seedlings had typical symptoms, but control seedlings were healthy. Fungal isolates were only recovered from symptomatic stems and were morphologically identical to L. theobromae, completing Koch’s postulates. L. theobromae has a broad host range, causing numerous diseases, including canker and dieback of branch (Aguilera-Cogley et al. 2021), panicle blight (Mahadevakumar et al. 2023), root rot (Abd-El Ghani and Fatouh 2005), and fruit rot (Freire et al. 2011) in many regions. To our knowledge, this is the first report of L. theobromae causing stem brown rot of loquat in China and will aid study of the epidemiology and integrated management of the disease.The author(s) declare no conflict of interest.References:Abd-El Ghani, H. S., and Fatouh, H. M. 2005. Egypt. J. Phytopathol. 33:107. Google ScholarAguilera-Cogley, V., et al. 2021. New Dis. Rep. 45:e12063. https://doi.org/10.1002/ndr2.12063 Google ScholarAlves, A., et al. 2008. Fungal Divers. 28:1. ISI, Google ScholarCarbone, I., and Kohn, L. M. 1999. Mycologia 91:553. https://doi.org/10.1080/00275514.1999.12061051 Crossref, ISI, Google ScholarFreire, F. C. O., et al. 2011. Essentia 12:53. Google ScholarGlass, N. L., and Donaldson, G. C. 1995. Appl. Environ. Microbiol. 61:1323. https://doi.org/10.1128/aem.61.4.1323-1330.1995 Crossref, ISI, Google ScholarMahadevakumar, S., et al. 2023. Plant Dis. 107:225. https://doi.org/10.1094/PDIS-04-22-0867-PDN Link, ISI, 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 ScholarFunding: Funding was provided by National Natural Science Foundation of China (31260062), Joint Special Fund for Basic Research of Local Universities in Yunnan Province (202001BA070001-157), the key project from Mengzi Agricultural and Rural Bureau, Science and Technology Innovation Team for Green Prevention and Control on Pests and Diseases from Special Fruits in South Yunnan, China (2020102).The author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Just PublishedSubscribeISSN:0191-2917e-ISSN:1943-7692 Metrics Article History Published: 29 Jun 2023First Look: 23 Jan 2023Accepted: 16 Jan 2023 Information© 2023 The American Phytopathological SocietyFundingNational Natural Science Foundation of ChinaGrant/Award Number: 31260062Joint Special Fund for Basic Research of Local Universities in Yunnan ProvinceGrant/Award Number: 202001BA070001-157Mengzi Agricultural and Rural BureauGrant/Award Number: 2020102KeywordsLasiodiplodia theobromaeloquatstem brown rotThe author(s) declare no conflict of interest.PDF download