First report of Puccinia gibberosa on blue oatgrass (Helictotrichon sempervirens) in Canada, with taxonomic revision of the rust species

AbstractHelictotrichon sempervirens (blue oatgrass) is a perennial grass widely grown for ornamental use in Canada. Rusted blue oatgrass plants with diseased leaves covered with uredinia were collected from two locations at metropolitan Vancouver, British Columbia (BC), in summer 2022. The rust fungus was identified as Puccinia gibberosa (= P. coronata var. gibberosa) based on combined results of morphological characteristics and molecular analyses. The internal transcribed spacer two (ITS2) and partial large subunit ribosomal DNA were amplified and sequenced. The sequence obtained for the rust fungus showed 99.9% identity with the previously reported P. coronata var. gibberosa from USA. This is the first report of rust caused by P. gibberosa on blue oatgrass in Canada. Evidence from phylogenetic analyses supports the recognition of this rust at the species level. A revised description for P. gibberosa is provided, including synonyms, host range and distribution across the globe, and incorporating comprehensive molecular and morphological results for several North American and European specimens. In addition, a lectotype and an epitype are designated here for the rust species.Helictotrichon sempervirens (avoine sempervirente) est une graminée vivace cultivée couramment à des fins ornementales au Canada. À l’été 2022, des plants d’avoine sempervirente rouillée dont les feuilles infectées étaient couvertes d’urédosores ont été collectés à deux endroits de la région métropolitaine de Vancouver, en Colombie-Britannique. Le champignon de la rouille a été identifié en tant que Puccinia gibberosa (= P. coronata var. gibberosa), en se basant sur les résultats combinés des analyses des caractéristiques morphologiques et moléculaires. L’espaceur transcrit interne 2 (ITS2) et la grande sous-unité partielle de l’ADN ribosomique ont été amplifiés et séquencés. La séquence obtenue pour le champignon de la rouille était identique à 99,9 % à P. coronata var. gibberosa préalablement rapporté aux États-Unis. Il s’agit de la première mention de rouille causée par P. gibberosa chez l’avoine sempervirente au Canada. L’indice obtenu des analyses phylogénétiques soutient la reconnaissance de cette rouille au niveau de l’espèce. Une description révisée de P. gibberosa est fournie, y compris les synonymes, la gamme d’hôtes ainsi que l’aire de distribution mondiale, et comprend les résultats détaillés des analyses moléculaires et morphologiques pour plusieurs spécimens nord-américains et européens. En outre, un lectotype et un épitype ont été sélectionnés pour l’espèce de rouille.Keywords: British Columbiafungal diseasePoaceaePuccinialesrust fungiKEYWORDS: champignons de la rouilleColombie-Britanniquemaladie fongiquepoacéesPuccinialesDisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. AcknowledgementsWe would like to thank Dr. Karen Golinski, collections curator of Bryophytes, Lichens & Fungi, and Spencer Goyette, curatorial assistant at the UBC herbarium, for making it possible for the first author to use microscope and photomicrography system. We are grateful to the Swedish Museum of Natural History (S) and the Czech Republic Moravian Museum (BRNM) for previous loans of authentic and type specimens, to the Canadian National Mycological Herbarium (DAOM) for handling DAOM 984916, and also to Professor Paul A. Smith (University of Southampton) and Dr. R. Nigel Stringer (National Botanic Garden of Wales) for sharing information and the specimen from the UK, DAOM 985058, which is a subsample of specimen # E00982881 at the Royal Botanic Garden Herbarium in Edinburgh (https://data.rbge.org.uk/herb/E00982881). In addition, we thank Dr. Uwe Braun, Martin-Luther-Universität, Halle (Saale), Germany for advising on the nomenclatural aspects and Julie Carey at Agriculture and Agri-Food Canada (AAFC) in Ottawa for technical assistance with DNA extraction and sequencing.Additional informationFundingThe funding for this work came in part from the funding provided to Gurcharn S. Brar by The University of British Columbia (UBC), BC Peace River Grain Industry Development Council, and by Saskatchewan Wheat Development Commission. This study was also supported by Agriculture and Agri-Food Canada Project ID J-002272.