First Report of Neofusicoccum mangiferae Causing Shoot Blight of Sassafras tzumu in China

Abstract

HomePlant DiseaseVol. 104, No. 7First Report of Neofusicoccum mangiferae Causing Shoot Blight of Sassafras tzumu in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Neofusicoccum mangiferae Causing Shoot Blight of Sassafras tzumu in ChinaYu Wan, Xin-Yu Wang, Long-Xi He, Wu Xu, and Li-Hua ZhuYu WanCollege of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, Nanjing, Jiangsu 210037, ChinaSearch for more papers by this author, Xin-Yu WangCollege of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, Nanjing, Jiangsu 210037, ChinaSearch for more papers by this author, Long-Xi HeJiangxi Forest Pest Control and Quarantine Bureau, Nanchang, Jiangxi 330038, ChinaSearch for more papers by this author, Wu XuShanghai Qingpu Forestry Station, Shanghai, 201700, ChinaSearch for more papers by this author, and Li-Hua Zhu†Corresponding author: L.-H. Zhu; E-mail Address: lhzhu@njfu.com.cnhttp://orcid.org/0000-0003-2740-4980College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, ChinaSearch for more papers by this author AffiliationsAuthors and Affiliations Yu Wan1 2 Xin-Yu Wang1 2 Long-Xi He3 Wu Xu4 Li-Hua Zhu1 † 1College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu 210037, China 2Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing, Jiangsu 210037, China 3Jiangxi Forest Pest Control and Quarantine Bureau, Nanchang, Jiangxi 330038, China 4Shanghai Qingpu Forestry Station, Shanghai, 201700, China Published Online:7 May 2020https://doi.org/10.1094/PDIS-11-19-2521-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Sassafras tzumu Hemsl. is native to China and was widely planted in central and southwestern China (Wu et al. 2008). The wood of S. tzumu is used for boat and furniture making, and the roots and bark are used in traditional Chinese medicine. Since 2014, severe blight of branches has been observed on S. tzumu in Yichun, Jiangxi, China. Symptoms began as brown round or elliptical necrosis spots at the area where the petioles attached to the branch; the spot gradually expanded to form a lesion and eventually caused wilting of the leaves. Finally, the lesion girdled the branch and killed it. A large number of dark brown to black stromatic conidiomata developed on the lesions. Small pieces of symptomatic stems were surface sterilized in 75% ethanol for 30 s, 1% NaClO for 90 s, rinsed with sterile water, plated on potato dextrose agar (PDA), and incubated at 25°C for 7 days. Fungal colonies were observed, and monosporic cultures of those colonies were obtained. A representative isolate, Sa-8, was obtained and deposited in the China Forestry Culture Collection Center (CFCC 53952). On PDA, the isolate developed white-gray, circular colonies with aerial mycelia and scalloped margins. The colonies turned to dark-gray after 5 days of incubation. At the beginning, conidia were hyaline, ellipsoid or fusiform, and nonseptated. With time, conidia became brown, two-celled, and measured 13.5 ± 1.4 × 7.3 ± 0.5 μm. Conidia morphology was similar to descriptions of Neofusicoccum sp. (Phillips et al. 2013). For molecular identification, genomic DNA of Sa-8 was extracted and amplified with internal transcribed spacer (ITS) primers (ITS1 and ITS4) (White et al. 1990), with the nuclear ribosomal 18S RNA small subunit (SSU), large subunit (LSU), elongation factor 1-alpha (EF1-α), and β-tubulin (β-tub) genes being amplified with primers NS1/NS4 (White et al. 1990), LR0R/LR05 (Schoch et al. 2009), EF1-F/EF1-R, and βt2a/βt2b (Glass and Donaldson 1995), respectively. The sequences were deposited in GenBank (accession nos. MK757880 [ITS], MK757885 [LSU], MN413328 [EF1-α], MN413329 [β-tub], and MK757888 [SSU]). BLAST results showed high similarities with sequences of Neofusicoccum mangiferae (JN688956.1 [ITS], identities = 525/525 [100%]; NG055730.1 [LSU], identities = 864/864, [100%]; EU673153 [SSU], identities = 924/933 [99%]; and KY000153 [β-tub], identities = 392/397 [99%]) and Dothiorella guttulata (KY815020.1 [EF1-α], identities = 353/360 [98%]). Phylogenetic analyses based on the combined sequences placed Sa-8 in the clade of N. mangiferae with 88% bootstrap support. Based on the morphological and molecular data, the isolate was identified as N. mangiferae (Syd. & P. Syd.) (Crous et al. 2006). Pathogenicity tests were performed on ten 1-year-old seedlings of S. tzumu. The stems of seedlings were wounded with a sterile needle, and mycelial plugs of Sa-8 on PDA were placed on the wounds and covered with Parafilm. Seedlings inoculated with PDA plugs were used as controls. Seedlings were incubated in a greenhouse at 25°C and a 16-h photoperiod. All seedlings inoculated with Sa-8 developed brown necrotic spots 5 days after inoculation and were blighted in 12 days. No symptoms were observed on the controls. The same fungus was reisolated from symptomatic stems. This is the first report of N. mangiferae causing shoot blight on S. tzumu. The disease has caused mortality to thousands of trees and has become a threat to the survival of S. tzumu. These results provided information for developing control strategies for this disease.The author(s) declare no conflict of interest.