This research aims to determine whether genetically distinct populations of the foliar pine pathogen, Dothistroma septosporum are phenotypically different from one another. The disease Dothistroma needle blight (DNB), caused by pathogen D. septosporum, decreases tree resilience, causes significant timber losses, sometimes mortality, and has led to large-scale species change on the Public Forest Estate. Analyses of neutral microsatellite markers reveals different populations of the pathogen exist across Britain, but critical knowledge gaps prevent our understanding the risks these different populations pose to our treescapes. FR, UK-CEH and Fera are collaborating to study these populations, supported by Defra’s Future Proofing Plant Health (FPPH) grant in 2023-24.
Five D. septosporum populations are being examined – one originating largely from exotic lodgepole pine plantations in the Central region of Scotland (‘LP’), one from northern Scotland on Scots pine (‘NS’), one predominantly from non-native Corsican pine (‘Southern’), one population found across Britain (RB) and, for comparison, an outlying eastern European population of D. septosporum originating from Turkey.
The aim is to address the following four research questions:
Studies of the pathogen growing on artificial (agar) media reveal significant variation between D. septosporum isolates in their responses to media type and temperature. Optimal temperature for growth is 20 °C compared with 15 and 25 °C. The pathogen grows very slowly on artificial media, but even more slowly when host material (crushed lodgepole, Corsican or Scots pine needles) is incorporated into the agar. Interestingly, there seems to be more variation in growth rates between the different isolates than between the D. septosporum populations.
When host material is artificially inoculated with pathogen spores, there is again a considerable amount of variation in colonisation. More D. septosporum fruit bodies are seen on lodgepole pine than Scots and Corsican pine (see the attached graph), and Scots pine needles exhibit the greatest browning in response to spore inoculation. Dothistroma septosporum colonisation of all inoculated needles is currently being confirmed and quantified using RT-PCR.
FR is leading this project.
Pine species comprise 28% Britain’s conifer forests and are the bedrock of nationally important habitats including the New Forest and Thetford Chase in England and Scotland’s ancient Caledonian forests. However, most pine species grown in Britain are susceptible to the foliar pathogen Dothistroma septosporum which has had landscape-scale impacts on forests since the mid-1990s (insert figure of banded needle). Dothistroma needle blight (DNB) decreases tree resilience, causes significant timber losses, sometimes mortality, and has led to large-scale species change on the Public Forest Estate. Analyses of neutral microsatellite markers has revealed the existence of different populations of D. septosporum in Britain. This FPPH project was established to help us understand the risks these different populations pose to our treescapes.
The behaviour of the different isolates and populations is being investigated through a combination of laboratory bioassays on artificial and host substrates, combined with molecular tools and the analytical technique, LC-MS, working with our collaborators, UK-CEH and Fera.
Principal Investigator