First Report of Anthracnose Caused by Colletotrichum nymphaeae on Loquat Fruit in China

Abstract

HomePlant DiseaseVol. 102, No. 1First Report of Anthracnose Caused by Colletotrichum nymphaeae on Loquat Fruit in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Anthracnose Caused by Colletotrichum nymphaeae on Loquat Fruit in ChinaW. X. Wu, Y. Liu, X. Q. Huang, and L. ZhangW. X. WuSearch for more papers by this author, Y. Liu†Corresponding author: Y. Liu; E-mail: E-mail Address: [email protected]Search for more papers by this author, X. Q. HuangSearch for more papers by this author, and L. ZhangSearch for more papers by this authorAffiliationsAuthors and Affiliations W. X. Wu Y. Liu † X. Q. Huang L. Zhang , Institute of Plant Protection, Sichuan Academy of Agricultural Sciences, Chengdu 610066, China; Key Laboratory of Integrated Pest Management in Southwest Agriculture Crops of Ministry of Agriculture, Chengdu 610066, China. Published Online:18 Oct 2017https://doi.org/10.1094/PDIS-06-17-0828-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Loquat (Eriobotrya japonica [Thunb.] Lindl.) is one of most important summer fruit crops in China. From May through June 2017, losses associated with fruit anthracnose of at least 3% were observed on stored loquats (cv. Dawuxing) from several commercial orchards in the districts surrounding Chengdu, Sichuan Province. Lesions on the surface of affected fruits were round, deep brown, 1 to 3 cm in diameter, and covered with orange acervuli. Fruits completely rotted with age. Twenty-four symptomatic fruits were collected in three different orchards. Diseased fruit tissues were excised and cut into pieces (5 mm × 5 mm), surface-sterilized in 5% NaOCl for 10 min, 75% ethanol for 60 s, and rinsed three times with sterilized distilled water. The samples were plated on potato dextrose agar (PDA) and incubated at 25 ± 1°C in the dark. The fungal colonies were similar in color varying from white to gray on the upper surface and being mostly orange on the bottom surface. Conidia were hyaline, smooth-walled, aseptate, straight, cylindrical to cylindric-clavate, 13 to 19 × 4 to 5.5 μm, with one end round and one end slightly acute or both ends round. These characteristics match with that described for Colletotrichum acutatum sensu lato. Isolate CDMF-1 was selected as a representative strain for further tests. Partial sequences of the ITS-rDNA, GAPDH, CHS-1, HIS3, ACT, and TUB2 gene regions were used for strain identification (Damm et al. 2012). Sequences were deposited in GenBank (accession nos. MF187553, MF278011–15). Maximum parsimony analysis (MP) was performed on the multilocus alignment (ITS, GAPDH, CHS-1, HIS3, ACT, TUB2) to confirm the identity of the isolate, and the isolate clustered together with C. nymphaeae, as also suggested by the BLAST results. Based on morphology and molecular identification, CDMF-1 was identified as C. nymphaeae (part of the C. acutatum species complex). In order to confirm pathogenicity, freshly picked and healthy loquat fruit were wound-inoculated with a 10 µl droplet of conidia suspension (1 to 3 × 106 conidia/ml); fruits inoculated with sterile water were used as negative controls. Inoculated and control samples were incubated in the laboratory in the dark under moist conditions at 25 ± 1°C and relative humidity at 80 to 85%. Pathogenicity tests were conducted three times. After 3 days, fruit inoculated with conidial suspension presented symptoms similar to that observed in the field, and no symptoms were observed on negative control. The pathogen was reisolated from symptomatic fruit, fulfilling the Koch’s postulates. Several species of the C. acutatum species complex, namely C. acutatum and C. gloeosporioides, have been reported to cause loquat fruit rot (Cao and Zheng 2010; Naz et al. 2017). C. nymphaeae has previously been reported to cause bitter rot on apples in southern Brazil (Velho et al. 2014), but to our knowledge, this is the first report of C. nymphaeae causing loquat anthracnose worldwide.