First Report of Grammothele lineata Causing Stem Rot of Areca catechu in Hainan Province, China

Areca catechu L. (areca) belongs to the Arecaceae family, which is composed of 181 genera and 2,600 species (Christenhusz Byng 2016), cultivated extensively in Southern Southeastern Asia (Peng et al. 2015). has a long history for its important economic medicinal benefits one most commercial crops Hainan province, China. In recent years, root rot stem diseases have occurred, causing areca plants wither even die. The serious symptoms mainly appeared province (Li 2006). March 2018, rotten tissues diseased were observed become brittle, brown, black from base root; outer leaves turned yellow, dry, dropping plantations Qionghai county. disease can spread individual whole plantation two with characteristics large-scale occurrence rapid transmission, huge losses. Diseased (5 × 5 mm) disinfected 75% ethanol 30 s, 1% HgCl2 1 min, washed sterile water, placed on potato dextrose agar (PDA) medium incubated at 28°C (Gao 2019). Pure isolates obtained by transferring mycelium around PDA several times. colonies white cottony after culturing 7 days. reverse side colony was yellowish white. Basidiospores hyaline, thin-walled, smooth, 1.7-1.8 x 1.6-1.7 μm (n=30) size circular or ellipse shape, addition dimitic hyphal system (Das 2017). For molecular identification, genomic DNA isolate extracted using thermolysis method (Zhang 2010). ribosomal internal transcribed spacer (ITS) region amplified primer pairs ITS1/ITS4 (White 1990), fragments sequenced. ITS sequence (GenBank accession No. MW534416) had 99.36% identity reference KX013157) Grammothele lineata Berk. & M.A. Curtis. A phylogenetic tree constructed software MEGA7 neighbor-joining method, showing that grouped same clade as G. lineata. To fulfil Koch’s postulates, pathogenicity test performed stems 6-month-old healthy seedlings. Stem surfaces sterilized 70% rinsed three times gently stabbed needle, then inoculated 1-cm-diameter colonized disk 7-day culture wounds, moistened wet cotton, wrapped fresh plastic wrap. Plants plugs used control. inoculation assay carried out twice, five both control treatment each test. After 20 days, pathogen exhibited symptoms, began yellow shrunken, while only surface discolored slightly inner tissue undamaged. fungus re-isolated infected stems. Based morphological observations analysis, identified As far we know, this first report