807/241 Late Blight Mating Types

Aim: To examine whether the GB population of P. infestans had changed since the mid 1990s and if the A2 mating type had increased in frequency.

European populations of the late-blight pathogen, Phytophthora infestans, include both mating types (A1, A2). In the mid 1990s, GB-wide surveys showed that most crops had a single clonal lineage of A1 mating type; the A2 mating type was detected at less than 10% of sites. 

Samples of blighted foliage were collected by Blight Scout volunteers as part of the Fight Against Blight (FAB) campaign and sent to CSL for confirmation of the presence of P. infestans. Positive samples were forwarded to the Sarvari Research Trust (SRT) for further analysis. In 2005, the pathogenicity of previously collected isolates was compared under field conditions. The work has indicated a change in the frequency of the A2 mating type in England, however as the results were based on a limited number of samples, further research has been carrried out in project R274.

Two reports are available for downloading. The second describes the frequency of A1 and A2 mating type in FAB samples and the results from the studies of the pathogenicity of different isolates and the characterisation of the A2 isolates. The first report provides information on the A1 isolates from the FAB campaign and on additional samples collected by staff at SRT.

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