First Report of Leaf Spot on Malania oleifera Caused by Botryosphaeria fabicerciana in China.

Abstract

HomePlant DiseaseVol. 106, No. 6First Report of Leaf Spot on Malania oleifera Caused by Botryosphaeria fabicerciana in China PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Leaf Spot on Malania oleifera Caused by Botryosphaeria fabicerciana in ChinaYue Pan, Pengfei Wang, Wandong Chen, Guichai Yang, Yingjie Gu, Junwei Wang, and Juan WangYue Panhttps://orcid.org/0000-0002-2092-2366Eco-development Academy, Southwest Forestry University, Kunming 650224, ChinaSearch for more papers by this author, Pengfei WangCollege of Forestry, Southwest Forestry University, Kunming 650224, ChinaSearch for more papers by this author, Wandong ChenCollege of Forestry, Southwest Forestry University, Kunming 650224, ChinaSearch for more papers by this author, Guichai YangCollege of Garden and Horticulture, Southwest Forestry University, Kunming 650224, ChinaSearch for more papers by this author, Yingjie GuCollege of Forestry, Southwest Forestry University, Kunming 650224, ChinaSearch for more papers by this author, Junwei WangSchool of Geography and Ecotourism, Southwest Forestry University, Kunming 650224, ChinaSearch for more papers by this author, and Juan Wang†Corresponding author: J. Wang; E-mail Address: schima@163.comEco-development Academy, Southwest Forestry University, Kunming 650224, ChinaSearch for more papers by this authorAffiliationsAuthors and Affiliations Yue Pan1 Pengfei Wang2 Wandong Chen2 Guichai Yang3 Yingjie Gu2 Junwei Wang4 Juan Wang1 † 1Eco-development Academy, Southwest Forestry University, Kunming 650224, China 2College of Forestry, Southwest Forestry University, Kunming 650224, China 3College of Garden and Horticulture, Southwest Forestry University, Kunming 650224, China 4School of Geography and Ecotourism, Southwest Forestry University, Kunming 650224, China Published Online:11 May 2022https://doi.org/10.1094/PDIS-09-21-2038-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleMalania oleifera Chun & S. K. Lee is an endangered plant species in China with rich nervonic acid in seeds, and, thus, has important ecological and economic value (Fu 1992; Tang et al. 2013). Brown leaf spots were observed on 3-year-old M. oleifera plants in summer 2019 in Guangnan County, Yunnan Province, China (24°05′26″N, 105°05′07″E). A total of 100 trees within 0.3 ha of mountainous area were investigated, and eight (8%) showed disease symptoms. Initially, small, brown irregular spots appeared on the tip and margin of the leaf, and then gradually expanded to the whole leaf. Ten symptomatic leaves were randomly collected from different plants for fungal isolation. They were washed with running tap water, sterilized with 75% ethanol for 3 min and 1% NaOCl for 2 min, and rinsed in sterile distilled water three times. The leaves were cut into 5 × 5 mm2 segments and cultured on potato dextrose agar (PDA) at 25°C in the dark after air drying. In total, 12 morphologically similar fungal isolates were obtained. Colonies of the fungal culture initially appeared white, turned gray from the center between 3 to 6 days, and then became dark gray with cottony aerial mycelium 9 days later. To induce sporulation, the cultures were placed on 2% water agar (WA) with autoclaved pine needles and were incubated at 25°C under near-ultraviolet light as described by Chen et al. (2011). Globose conidiomata developed on pine needle surfaces after 10 days. Conidia were hyaline, unicellular, aseptate, fusiform with apex acute and base truncate, and 18.62 to 26.14 × 4.80 to 7.63 μm (average 21.77 × 5.91 μm, n = 50). The morphological characteristics resembled those of Botryosphaeria fabicerciana (S.F. Chen, D. Pavlic, M.J. Wingf. & X.D. Zhou) A.J.L. Phillips & A. Alves (Phillips et al. 2013). The internal transcribed spacer (ITS) region and the translation elongation factor 1-α gene (EF1-α) regions of a representative isolate (CGMCC3.20320) were amplified using primers ITS1F/ITS4 and EF1-728F/EF1-986R (Carbone and Kohn 1999; White et al. 1990), respectively. The obtained sequences (GenBank accession nos. MW642163 and MW651965) showed 99.80% (identity = 505/506) and 99.27% (identity = 272/274) similarity with the corresponding genes of ex-type CMW 27094 of Fusicoccum fabicercianum S.F. Chen, D. Pavlic, M.J. Wingf. & X.D. Zhou, now B. fabicerciana (GenBank accession nos. HQ332197 and HQ332213). The pathogenicity of the selected isolate (CGMCC3.20320) was evaluated by leaf inoculation of 1-year-old M. oleifera seedlings. Mycelial plugs (5 mm) of B. fabicerciana from a 7-day-old culture were applied on leaves wounded with sterile scalpels. Controls were inoculated with sterile PDA plugs. Each treatment was repeated six times. Inoculated and control plants were kept in a greenhouse at 25°C and 80% relative humidity, with a 12-h photoperiod. After 10 days, irregular brown spots appeared on all inoculated leaves, whereas there were no spots from control plants. Botryosphaeria fabicerciana was reisolated only from symptomatic leaves, fulfilling Koch’s postulates. Previous studies indicated that this fungus can cause stem lesions on Eucalyptus and trunk cankers on Carya cathayensis in China (Chen et al. 2011; Zhuang et al. 2021). To our knowledge, this represents the first report of B. fabicerciana causing leaf spot on M. oleifera in China.The author(s) declare no conflict of interest.