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Isolates of recently spreading races of yellow rust from wheat and triticale in Europe were analysed using virulence phenotypic data of 2605 isolates sampled in 12 countries between 2000 and 2014. A subset of 239 isolates was investigated by microsatellite markers. At least three races of non-European origin, termed 'Warrior', 'Kranich' and 'Triticale aggressive', were identified in the post-2011 population. The Warrior race was already present in high frequencies in the first year of detection in most European countries and to a large extent it replaced the pre-2011 European population. In contrast, the two other exotic races were localized to certain regions and/or crop type. The presence already of at least six multilocus genotypes of the Warrior race and five genotypes of the Kranich race in the first year of detection and across large areas is consistent with a hypothesis of aerial spread from genetically diverse source populations. A comparison with reference isolates sampled from six continents suggested that the Warrior and Kranich races originated from sexually recombining populations in the centre of diversity of the yellow rust fungus in the near-Himalayan region of Asia. However, the Triticale aggressive race was most similar to populations in the Middle East/Central Asia. The study illustrated the potential role of sexual Puccinia striiformis populations as a reservoir for new races replacing distant clonal populations. [ABSTRACT FROM AUTHOR]

Stem rust, caused by Puccinia graminis , is a destructive group of diseases. The pathogen uses Berberis species as alternate hosts to complete its life cycle. B . vulgaris and the endemic species B. hispanica and B. garciae are present in Spain. The objective of this study was to investigate the functionality of the indigenous barberry as alternate hosts. Field surveys were conducted in 2018 and 2019 in Huesca, Teruel and Albacete provinces of Spain. Aecial samples on barberry were analysed via infection assays and DNA analysis. B . garciae was predominant in Huesca and Teruel provinces, often found in the field margins of cereal crops. Aecial infections on B . garciae were observed in May and uredinial infections on cereal crops in June. Scattered B . hispanica bushes were occasionally found near cereal crops in Albacete, where aecial infections on B . hispanica were observed in June when most cereal crops were mature. Infection assays using aeciospores resulted in stem rust infections on susceptible genotypes of wheat, barley, rye and oat, indicating the presence of the sexual cycle for P . graminis f. sp. tritici , f. sp. secalis and f. sp. avenae . Sequence analyses from aecial samples supported this finding as well as the presence of Puccinia brachypodii . This study provides the first evidence that indigenous Berberis species play an active role in the sexual cycle of P . graminis under natural conditions in Spain., (© 2022 The Authors. Plant Pathology published by John Wiley & Sons Ltd on behalf of British Society for Plant Pathology. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)