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Has S cots pine ( Pinus sylvestris ) co‐evolved with Dothistroma septosporum in S cotland? Evidence for spatial heterogeneity in the susceptibility of native provenances

2016; Wiley; Volume: 9; Issue: 8 Linguagem: Inglês

10.1111/eva.12395

1752-4571

Annika Perry, A. V. Brown, Stephen Cavers, Joan Cottrell, Richard A. Ennos,

Botany and Plant Ecology Studies

Abstract Spatial heterogeneity in pathogen pressure leads to genetic variation in, and evolution of, disease‐related traits among host populations. In contrast, hosts are expected to be highly susceptible to exotic pathogens as there has been no evolution of defence responses. Host response to pathogens can therefore be an indicator of a novel or endemic pathosystem. Currently, the most significant threat to native B ritish S cots pine ( P inus sylvestris ) forests is D othistroma needle blight ( DNB ) caused by the foliar pathogen D othistroma septosporum which is presumed to be exotic. A progeny–provenance trial of 6‐year‐old S cots pine, comprising eight native provenances each with four families in six blocks, was translocated in A pril 2013 to a clear‐fell site in G alloway adjacent to a DNB ‐infected forest. Susceptibility to D . septosporum , measured as DNB severity (estimated percentage nongreen current‐year needles), was assessed visually over 2 years (2013–2014 and 2014–2015; two assessments per year). There were highly significant differences in susceptibility among provenances but not among families for each annual assessment. Provenance mean susceptibility to D . septosporum was negatively and significantly associated with water‐related variables at site of origin, potentially due to the evolution of low susceptibility in the host in response to high historical pathogen pressure.