First Report of Botryosphaeria dothidea Causing Canker of Acer platanoides in China

Abstract

HomePlant DiseaseVol. 99, No. 12First Report of Botryosphaeria dothidea Causing Canker of Acer platanoides in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Botryosphaeria dothidea Causing Canker of Acer platanoides in ChinaX. Wang, Y. X. Li, H. X. Dong, X. Z. Jia, and X. Y. ZhangX. WangSearch for more papers by this author, Y. X. LiSearch for more papers by this author, H. X. DongSearch for more papers by this author, X. Z. JiaSearch for more papers by this author, and X. Y. ZhangSearch for more papers by this authorAffiliationsAuthors and Affiliations X. Wang Y. X. Li H. X. Dong X. Z. Jia X. Y. Zhang , Key Laboratory of Forest Protection, State Forestry Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, P.R. China 100091; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing Jiangsu, China 210037. Published Online:13 Nov 2015https://doi.org/10.1094/PDIS-03-15-0265-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In November of 2014, elongated oval-shaped cankers were observed on Norway maple (Acer platanoides) in a gardening nursery located in Henan Province of east-central China. The cankers were concentrated on the trunk and extended up to branches as disease developed. Bark on cankers was necrotic with black liquid visible. Cross sections of cankers revealed abnormally dark-brown tissues below the bark. Healthy tissues and tissue at the margins of cankers were cut into 1-mm2 pieces, sterilized in 75% ethanol for 30 s, then soaked in 1% sodium hypochlorite for 30 s, washed with sterile water, and finally placed onto potato dextrose agar (PDA). After 1 day of incubation at room temperature, white fluffy mycelia grew from diseased tissues. After 2 to 3 days, the centers of fungal colonies were dark gray. By 5 days, mycelia extended to the edges of 9-cm plates. After 7 days, entire colonies were dark gray and some pycnidia developed on the dark-gray PDA culture after about 30 days. Pycnidia were globose, and the hyaline cylindrical conidiophores or conidiogenous cells were attached to the inner walls of pycnidia. Conidia were hyaline, fusoid to ellipsoid, aseptate, with a subtruncate base, and measured 20 to 28 × 5.5 to 8.5 μm (mean dimensions of 50 conidia: 23 × 7 μm). DNA was extracted from the mycelia of one colony and carried out as specified by the manufacturer (plant genomic DNA kit, Tiangen, Beijing, China). The rDNA internal transcribed spacer (ITS) region was amplified with primers ITS1 and ITS4 and the ITS region of rDNA was sequenced and deposited in GenBank (Accession No. KP749828). The 574-bp region showed 100% identity to ITS sequence reference isolates of Botryosphaeria dothidea (KJ801792) (Zhou et al. 2015). The pathogen was identified as B. dothidea (Moug.) Ces. & De Not. on the basis of morphology and ITS gene sequence. The strain was deposited in the culture collection of Chinese Academy of Forestry and marked as CXY1813. Pathogenicity tests were done by inoculating each of five branches on one 3-year-old Norway maple tree with a mycelial plug (0.5-cm diameter) harvested from the margin of a 7-day-old colony. Five branches inoculated with plugs of PDA served as the negative control. After incubation for 20 days at 25°C, inoculated branches turned black and necrotic, while no signs or symptoms were observed on plants inoculated only with PDA. A fungus matching the description above was isolated from the diseased branches but not from the negative control. From these experiments, we infer that the cause of Norway maple canker is B. dothidea. This fungus was previously reported to cause canker on sycamore (Acer pseudoplatanus) in Italy (Turco et al. 2006). To our knowledge, this is the first report of B. dothidea causing canker of Acer platanoides in China.