Rust on <i>Hosta longipes</i> caused by <i>Puccinia oncospora</i> in Korea

Hosta longipes (Liliaceae), widely distributed throughout Korea, China, Japan, and eastern Russia, is one of the most popular ornamental perennials in public private gardens. In this species has long been used as a traditional medicine for treatment coughs, phlegm, burns, swelling asthma (Kim et al., 2014), its young leaves are also consumed salad vegetable. June 2016, rust disease was observed on H. plants growing naturally around stream at Mount Gongjaksan Hongcheon-gun, Korea (Fig. 1). The incidence rate c. 10%. Symptoms appeared yellowish, round, chlorotic spots upper surface infected 2) yellow to orange-coloured aecia corresponding lower petiole 3). After first findings, same 2017, 2019 2020. Herbarium specimens material were deposited University (Accession Nos. KUS-F29182, F29810, F30967, F31685). Leaves affected by infection examined under dissecting microscope (M205C; Leica, Germany), DIC (Axio Imager 2; Carl Zeiss, scanning electron (S-4800+EDS; Hitachi, Japan). Spermogonia mostly epiphyllous but rarely hypophyllous, densely grouped, pale brown, subepidermal. Aecia often yellow, cupulate with peridia, 196–300 μm diameter 4). Aeciospores hyaline, globose subglobose, angular, (20.2-)22.0-24.9(-27.4) × (17.0-)19.6-22.5(-24.2) (mean 23.4 21.0 μm) 5). Aeciospore wall verrucose 0.6-1.6 1.0 thickness 6). Uredinial telial stages not observed. These morphological characteristics consistent those Puccinia oncospora (Ji 2022). To confirm morphology-based identification, genomic DNA extracted from four using MagListo 5M plant Genomic Extraction Kit (Bioneer, Korea). Two ribosomal regions amplified: internal transcribed spacer (ITS) primers ITS5u ITS4rust (Pfunder 2001) large subunit (LSU) rDNA LRust1R LRust3 (Beenken 2012). resulting sequences GenBank OQ061206-9 ITS OQ073721-4 LSU) compared other reference BLASTn. Korean identical P. ex Trillium kamtschaticum Phalaris arundinacea (MW404821-5) LSU (MW404981-5). maximum-likelihood phylogenetic trees 7A) 7B) sequences, samples grouped high bootstrap supporting values 93% 96% LSU. recently described that so far only known where it completes life cycle forming an aecial stage (Melanthiaceae, previously Liliaceae) (Poaceae; Ji So far, three have recorded longipes, namely, funkiae, hemerocallidis, majanthemi (Hiratsuka & Sato, 1951; Farr Rossman, Also, complex sessilis considered parasitic 1951), phylogenetically morphologically distinguishable oncospora. our knowledge, record pathogen Korea. As there no records arundinacea, host oncospora, finding alternative necessary develop effective control measures. This work supported National Academy Agricultural Science grant (PJ0149560112020) Rural Development Administration,