First Report of Oat (Avena sativa) Root Rot Caused by Fusarium proliferatum in China

Abstract

HomePlant DiseaseVol. 104, No. 3First Report of Oat (Avena sativa) Root Rot Caused by Fusarium proliferatum in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Oat (Avena sativa) Root Rot Caused by Fusarium proliferatum in ChinaH. Chen, L. H. Xue, and C. J. LiH. ChenState Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, ChinaSearch for more papers by this author, L. H. Xuehttp://orcid.org/0000-0002-1158-2152State Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, ChinaSearch for more papers by this author, and C. J. Li†Corresponding author: C. J. Li; E-mail Address: chunjie@lzu.edu.cnhttp://orcid.org/0000-0002-3287-2140State Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, ChinaSearch for more papers by this author AffiliationsAuthors and Affiliations H. Chen L. H. Xue C. J. Li † State Key Laboratory of Grassland Agro-Ecosystems; Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs; Engineering Research Center of Grassland Industry, Ministry of Education; Gansu Tech Innovation Center of Western China Grassland Industry; College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China Published Online:30 Dec 2019https://doi.org/10.1094/PDIS-09-19-2000-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat In north and northeast China, oat (Avena sativa L.) is an important crop for local farmers, accounting for over 80% of the country’s total planting area of oat (Wang et al. 2019). During July and August 2018, severe outbreaks of seedling wilt were observed on oat with an incidence of approximately 5% in the farmland of Shandan County (38.22° N, 101.22° E), Zhangye City, Gansu Province. Symptoms included leaf yellowing, plant stunting, rotting of roots, and vascular discoloration in roots. The symptomatic plants were uprooted and collected from several incidence areas in the field. Discolored root tissues were disinfested by immersion in 75% ethanol for 30 s and 1% NaClO for 90 s, rinsed three times in sterilized water, plated on potato dextrose agar (PDA) medium, incubated at 22°C in the dark, and isolates purified by single-spore cultures (Leslie and Summerell 2006). Four single-spore cultures were consistently isolated with similar phenotypes. The colonies grew regularly in shape; the colonies were white, with older colonies becoming violet to dark. On carnation leaf agar, the microconidia were abundant, oval shaped with a flat base, single celled, and measured 5.9 to 12.5 × 2.6 to 3.8 μm (7.4 × 3.1 μm on average) (n = 50), and macroconidia were sparse, slender, two to three septate, and measured 19.7 to 36.8 × 1.9 to 2.5 μm (25.2 × 2.2 μm on average) (n = 50). No chlamydospores were observed. These phenotypical characteristics were consistent with previous descriptions of Fusarium species in general (Mun et al. 2012). Total DNA was extracted from 7-day-old aerial mycelium grown on PDA. Species identity was confirmed by sequencing partial sequences of EF1-α gene (EF1 and EF2 primers) (O’Donnell et al. 1998) and RPB2 regions (RPB2-5f2 and RPB2-7cr) (O’Donnell et al. 2010). Sequences for one isolate were deposited in GenBank under accessions MN245721 (RPB2) and MN245720 (EF1-α). A nucleotide BLAST search revealed EF1-α and RPB2 sequences to be 99% similar to the corresponding sequences of Fusarium proliferatum accession numbers MH582345.1 and MH582193.1, respectively. For pathogenicity tests, millet-seed-based inoculum of F. proliferatum was prepared using a modified procedure (Fang et al. 2011). Healthy oat seedlings were transplanted into plastic pots containing pasteurized potting mix infested with millet-seed-based inoculum of F. proliferatum at a rate of 0.5%. Control seedlings for comparison were transplanted into pots containing potting mix without inoculum. Plants were maintained for 22 days under greenhouse conditions at 18 to 25°C with all the inoculated plants developing symptoms similar to those observed in the field, whereas control plants remained healthy. The fungus was reisolated from the roots of inoculated plants and confirmed phenotypically and molecularly as F. proliferatum. F. proliferatum has been reported associated with root rot in soybean in Canada (Chang et al. 2015) and in alfalfa in China (Cong et al. 2016). To our knowledge, this is the first report of F. proliferatum causing root rot in oat in China. This study provides a basis for identifying pathogens causing oat root rot and managing the disease.The author(s) declare no conflict of interest.