International Symposium on Cereal Leaf Blights 2019 | University College Dublin, Ireland | 22-24 May 2019

Genomic and transcriptomic sequencing reveal a lack of diversity in European isolates of the causal agent of wheat leaf rust, Puccinia triticina

Rebecca Doherty*
John Innes centre

Guru Radhakrishnan
John Innes centre

Sarah Holdgate

Diane Saunders
John Innes centre

Poster Presentation
Evolution and Population Biology

Atrium, UCD O'Brien centre for Science
Poster 1

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Brown rust, also known as leaf rust, is caused by the obligate biotroph basidiomycete Puccinia triticina and is the most common rust disease of wheat worldwide. Phenotypic data in the virulence profiles of UK brown rust isolates over the last 12 years has revealed four races of interest. Whilst the genetic diversity of P. triticina has been monitored across the world through the use of Simple Sequence Repeat (SSR) and Random Amplified Polymorphism DNA (RAPD) markers, genomic data has only recently become available, opening up new avenues of research. A novel pathogen surveillance technique, termed ‘field pathogenomics’, has been used to characterise the population diversity of the related wheat rust pathogen, P. striiformis f. sp. tritici. The method allows rapid detection of pathogen variants directly from infected wheat samples taken from the field through transcriptomic sequencing of infected material. In this study, we are using a genomic approach in combination with the field pathogenomics technique to characterise the European brown rust population and genetic diversity. This ongoing work involves genome sequencing of 44 UK brown rust isolates from the years 2006-2015 to characterise the UK brown rust population in the years prior to this project, accompanied by transcriptomic sequencing, using our field pathogenomics technique of ~40 European field isolates from each of the 2017 and 2018 growing seasons. Population genetic analysis of 112 brown rust isolates illustrated that they are all closely related with very little genetic diversity. The next step is to link the differences in the virulence profiles between brown rust isolates to any commonalities in polymorphisms in candidate effector genes for isolates with similar virulence profiles. This will contribute to our understanding of brown rust, and how isolates with such similar genetic diversity can present the different virulence profiles seen in the UK prior to this study.