Pathogen Resources
Rationale
To enable the reliable genetic analysis of complex disease resistance traits in B. napus, a core collection of isolates of the two major fungal pathogens causing economic losses in oilseed rape crops, Pyrenopeziza brassicae and Leptosphaeria maculans, was established. The genetic diversity within the pathogen collection was analysed to ensure that the assembled collection represented the majority of the pathogen diversity. This was necessary in order to enable future reliable genetic analysis of specific pathogen-host interactions in combination with the host crop DFFS. Framework standard operating procedures were established so that they can be applied to other oilseed rape pathogens in future projects associated with OREGIN.Establishment of a worldwide OSR fungal pathogen resource collection
In 2003/04, 250 isolates of Leptosphaeria maculans and about 200 isolates of Pyrenopeziza brassicae were assembled at RRes from sources representative of the world wide distribution of stem canker and light leaf spot epiphytotics in OSR. Information on these isolates and their properties was maintained in spreadsheets and a prototype database of the culture collection was tested and then made available on the OREGIN website. In 2004/05, additional collections were made from sources in western Australia, France, Portugal, Sweden, Germany and Scotland and the culture collection of pathogen isolates was enlarged to 490 of Leptosphaeria maculans and about 250 of Pyrenopeziza brassicae. Information on the isolates and their properties was maintained in MS Excel spread sheets and then converted to a MySQL database for easy integration with the OREGIN website (http://www.oregin.info). Isolates sourced and annotated By April 2006, the culture collection comprised a total of 520 Leptosphaeria maculans and 259 Pyrenopeziza brassicae isolates from the UK and other sources worldwide (Fig. 2). These isolates are maintained on agar media at 4oC, and at -80oC as conidial suspensions in 10 % glycerol; the latter are kept in duplicates at Rothamsted Research and Warwick HRI. Information on isolates and their properties continues to be updated and is maintained in the pathogen database, together with facilities for selecting and ordering isolates .Secure storage of the “founder isolate” collection.
Stock cultures of all isolates are maintained in 10% glycerol at -80oC and as duplicate nutrient media slopes. DNA extracted from freeze-dried mycelia was isolated for analyseis of genetic diversity using molecular markers. For L. maculans, six minisatellite markers were initially evaluated. Amplified fragment length polymorphism (AFLP) markers were adopted for the characterization of P. brassicae isolates.
Worlwide distribution of the sources of isolates of the stem canker pathogen L. maculans collected within the OREGIN culture collection
Worlwide distribution of the sources of light leaf spot pathogen P. brassicae isolates collected within the OREGIN culture collection
