First Report of Leaf Spot of Salvia farinacea Caused by Alternaria alternata in China

Abstract

HomePlant DiseaseVol. 104, No. 9First Report of Leaf Spot of Salvia farinacea Caused by Alternaria alternata in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Leaf Spot of Salvia farinacea Caused by Alternaria alternata in ChinaJ. J. Ding, X. Gu, X. H. Yang, L. L. Yao, X. D. Gao, M. M. Zhang, and Y. G. LiJ. J. DingJiamusi Branch of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154000, ChinaSearch for more papers by this author, X. GuJiamusi Branch of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154000, ChinaSearch for more papers by this author, X. H. YangJiamusi Branch of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154000, ChinaSearch for more papers by this author, L. L. YaoJiamusi Branch of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154000, ChinaSearch for more papers by this author, X. D. GaoJiamusi Branch of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154000, ChinaSearch for more papers by this author, M. M. ZhangJiamusi Branch of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154000, ChinaSearch for more papers by this author, and Y. G. Li†Corresponding author: Y. G. Li; E-mail Address: neaulyg@126.comhttp://orcid.org/0000-0003-4582-2473Agricultural College, Northeast Agricultural University, Harbin 150030, ChinaSearch for more papers by this author AffiliationsAuthors and Affiliations J. J. Ding1 X. Gu1 X. H. Yang1 L. L. Yao1 X. D. Gao1 M. M. Zhang1 Y. G. Li2 † 1Jiamusi Branch of Heilongjiang Academy of Agricultural Sciences, Jiamusi 154000, China 2Agricultural College, Northeast Agricultural University, Harbin 150030, China Published Online:9 Jul 2020https://doi.org/10.1094/PDIS-02-20-0415-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Salvia farinacea Benth. is a herbaceous perennial plant. In July 2018, a leaf spot disease was observed on S. farinacea at four nurseries in Harbin, China, with approximately 50% of the plants diseased. Disease symptoms were irregular, necrotic spots on leaves (0.5 to 1 mm in diameter). Ten tissue samples from 10 individual plants were surface disinfested in 0.5% NaOCl for 5 min, rinsed three times in sterile distilled water, and cultured on potato dextrose agar (PDA) amended with antibiotics at 26°C. Six similar fungal cultures were isolated and subcultured. Single-conidium isolates were generated with methods reported previously (Leslie and Summerell 2006). Colonies on PDA were olive-green with a white margin, with black pigments and abundant aerial hyphae. Conidia were black to brown, obclavate to obpyriform, with a small beak in long sparsely branched chains on simple short conidiophores, measuring 4.6 to 14.2 μm in width and 8.2 to 30.8 μm in length (n = 50), and had one to four transverse and zero to three longitudinal septa. According to these morphological characteristics, all isolates were identified as a species of Alternaria (Simmons 2007). Genomic DNA was extracted from the mycelium of three representative isolates: XPC1, XPC3, and XPC6. The internal transcribed spacer region (ITS), translation elongation factor 1-α gene (TEF1), and glyceraldehyde 3-phosphate dehydrogenase (GPD) were amplified and sequenced using primers ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), and Gpd1/Gpd2 (Woudenberg et al. 2013). The consensus sequences (accession nos. MN733165 for ITS, MN756011 for TEF1, and MT108177 for GPD) were aligned using BLASTn in GenBank and were 100% identical to A. alternata strains ITC20 (accession no. KX987252.1), WCS1-5 (MK791316.1), and YJ1 (KP851968.1), respectively. To confirm pathogenicity of XPC1, XPC3, and XPC6, S. farinacea plants were grown in 15-cm pots containing a commercial potting mix (one plant/pot). At the five- to eight-leaf stage, three healthy plants were inoculated by spraying 50 μl of conidial suspension of the isolates (4 × 106 spores/ml) onto unwounded leaves. Three plants treated with sterile distilled water served as the control. All plants were placed in a humidity chamber (>95% relative humidity, 26°C) for 48 h after inoculation and then transferred into a greenhouse at 22/28°C. All inoculated leaves showed symptoms similar to those observed in the nursery 10 days after inoculation, whereas no symptoms were observed on the control leaves. The fungus was reisolated and confirmed to be A. alternata. A. alternata has previously been reported on Salvia spp. in Italy (Garibaldi et al. 2019) and Argentina (Kameniecki et al. 2013). To our knowledge, this is the first report of A. alternata on S. farinacea in China. Occurrence of the new disease caused by A. alternata should prompt full consideration for the use of proper disease management to protect S. farinacea.The author(s) declare no conflict of interest.