Substantial heritable variation for susceptibility to Dothistroma septosporum within populations of native British Scots pine (Pinus sylvestris).

The threat from pests and pathogens to native and commercially planted forest trees is unprecedented and expected to increase under climate change. The degree to which forests respond to threats from pathogens depends on their adaptive capacity, which is determined largely by genetically controlled variation in susceptibility of the individual trees within them and the heritability and evolvability of this trait. The most significant current threat to the economically and ecologically important species Scots pine (Pinus sylvestris) is dothistroma needle blight (DNB), caused by the foliar pathogen Dothistroma septosporum. A progeny‐population trial of 4‐year‐old Scots pine trees, comprising six populations from native Caledonian pinewoods each with three to five families in seven blocks, was artificially inoculated using a single isolate of D. septosporum. Susceptibility to D. septosporum, assessed as the percentage of non‐green needles, was measured regularly over a period of 61 days following inoculation, during which plants were maintained in conditions ideal for DNB development (warm; high humidity; high leaf wetness). There were significant differences in susceptibility to D. septosporum among families indicating that variation in this trait is heritable, with high estimates of narrow‐sense heritability (0.38–0.75) and evolvability (genetic coefficient of variation, 23.47). It is concluded that native Scots pine populations contain sufficient genetic diversity to evolve lower susceptibility to D. septosporum through natural selection in response to increased prevalence of this pathogen.

害虫和病原体对本地及商业种植的林木的威胁是前所未有的，并且在气候变化的情况下预计会增加。森林对病原体威胁的反应程度取决于其适应能力，而适应能力在很大程度上由林内个体树木易感性的遗传控制变异以及该性状的遗传力和进化能力所决定。当前对具有重要经济和生态价值的欧洲赤松（Pinus sylvestris）最严重的威胁是由叶部病原体松针红斑病菌（Dothistroma septosporum）引起的松针红斑病（DNB）。对4年生欧洲赤松的一个子代群体试验林进行了研究，该试验林包含来自本地喀里多尼亚松林的6个种群，每个种群在7个区组中有3到5个家系，使用松针红斑病菌的一个单菌株进行人工接种。在接种后的61天内定期测量对松针红斑病菌的易感性（以非绿色针叶的百分比来评估），在此期间，植株被维持在有利于松针红斑病发展的理想条件下（温暖、高湿度、高叶片湿润度）。家系之间对松针红斑病菌的易感性存在显著差异，这表明该性状的变异是可遗传的，狭义遗传力（0.38 - 0.75）和进化能力（遗传变异系数，23.47）的估计值较高。结论是，本地欧洲赤松种群包含足够的遗传多样性，能够通过自然选择对这种病原体的增加做出反应，从而进化出对松针红斑病菌较低的易感性。