First Report of Alternaria alternata Causing Leaf Blight on Actinidia arguta in Liaoning, China

Abstract

HomePlant DiseaseVol. 104, No. 10First Report of Alternaria alternata Causing Leaf Blight on Actinidia arguta in Liaoning, China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Alternaria alternata Causing Leaf Blight on Actinidia arguta in Liaoning, ChinaQin Wang, Qing-Shu Luan, Jian-Jun Wang, Xu Jiang, and Gang ChenQin Wanghttp://orcid.org/0000-0003-2932-8512Provincial Key Laboratory of Forest Protection, Liaoning Academy of Forestry, Shenyang 110032, ChinaSearch for more papers by this author, Qing-Shu LuanProvincial Key Laboratory of Forest Protection, Liaoning Academy of Forestry, Shenyang 110032, ChinaSearch for more papers by this author, Jian-Jun WangProvincial Key Laboratory of Forest Protection, Liaoning Academy of Forestry, Shenyang 110032, ChinaSearch for more papers by this author, Xu JiangProvincial Key Laboratory of Forest Protection, Liaoning Academy of Forestry, Shenyang 110032, ChinaSearch for more papers by this author, and Gang Chen†Corresponding author: G. Chen; E-mail Address: chengang1625@163.comProvincial Key Laboratory of Forest Protection, Liaoning Academy of Forestry, Shenyang 110032, ChinaSearch for more papers by this author AffiliationsAuthors and Affiliations Qin Wang Qing-Shu Luan Jian-Jun Wang Xu Jiang Gang Chen † Provincial Key Laboratory of Forest Protection, Liaoning Academy of Forestry, Shenyang 110032, China Published Online:18 Aug 2020https://doi.org/10.1094/PDIS-09-19-1871-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Actinidia arguta is a Chinese native fruiting vine and has been cultivated in several countries for its commercial advantages (Williams et al. 2003). During the 2017 and 2018 growing seasons, leaf spot and blight symptoms were observed on young and mature leaves of A. arguta at four orchards in Dandong, Liaoning Province, China, with the disease incidence ranging from 8 to 23%. To identify the pathogen, three symptomatic leaf samples from each of the plantations were selected for pathogen isolation. Eight isolates similar in appearance were obtained by the hyphal tip method. Colonies on potato carrot agar were cottony and were mouse gray or black olive. Conidiophores were simple or branched, straight or flexuous, brown in color, smooth, with one or more conidial scars. Conidia were borne solitary or in chains, brown or dark brown, obclavate, obpyriform or ellipsoid, with a cylindrical or coniform beak at the tip. Conidia ranged from 13.0 to 50 μm long (mean 31.3 μm) and 9 to 18 μm wide (mean 13.9 μm) with one to five transverse and rarely zero to three longitudinal septa. To make further identification, the rDNA internal transcribed spacer regions (ITS) and glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH) of all isolates were amplified using primer pairs ITS5/ITS4 and GDF1/GDR1, respectively. All isolates had identical ITS sequence and identical GAPDH sequence, exhibiting 100% identity with that of Alternaria alternata strain CBS 130265 (KP124391 for ITS, KP124243 for GAPDH). Only one representative sequence of each gene was submitted to GenBank (MN249500 for ITS, MN258117 for GAPDH). Based on morphological characteristics (Simmons 2007) and DNA sequence data, the pathogen was identified as A. alternata. For the pathogenicity test, one isolate was used for artificial inoculation in 3-year-old seedlings of A. arguta (cultivar Longcheng). Ten healthy leaves from three individuals were selected, sprayed with a suspension of 106 conidia/ml, and covered with plastic bags for 4 days. A control treatment with an equal number of leaves was sprayed with distilled water only. Symptoms identical to those observed in the field were observed 7 to 10 days after inoculation, whereas all control leaves were asymptomatic. A. alternata was consistently reisolated from inoculated leaves. A. alternata has previously been reported to cause fruit rot on A. arguta in Korean (Kim et al. 2017). However, to our knowledge, this is the first report of A. alternata causing leaf spots on A. arguta in China.The author(s) declare no conflict of interest.