Data from: Distribution and population structure of the anther smut fungus Microbotryum silenes-acaulis parasitizing an arctic-alpine plant

Cold-adapted organisms with current arctic-alpine distributions have persisted during the last glaciation in multiple ice-free refugia, leaving footprints in their population structure that contrast with temperate plants and animals. However, pathogens that live within hosts having arctic-alpine distributions have been little studied. Here, we therefore investigated the geographical range and population structure of a fungus parasitizing an arctic-alpine plant. A total of 1437 herbarium specimens of the plant Silene acaulis were examined, and the anther smut pathogen Microbotryum silenes-acaulis was present throughout the host’s geographic range. There was significantly greater incidence of anther smut disease in more northern latitudes and where the host locations were less dense, indicating a major influence of environmental factors and/or host demographic structure on the pathogen distribution. Genetic analyses with seven microsatellite markers on recent collections of 195 M. silenes-acaulis individuals revealed three main genetic clusters, in North America, northern Europe and southern Europe, likely corresponding to differentiation in distinct refugia during the last glaciation. The lower genetic diversity in northern Europe indicates postglacial recolonization northwards from southern refugia. This study combining herbarium surveys and population genetics thus uniquely reveals the effects of climate and environmental factors on a plant pathogen species with an arctic-alpine distribution.现分布于北极-高山区域的适冷生物，在末次冰期（last glaciation）期间于多处无冰避难所（ice-free refugia）存续，并在种群结构中留下了与温带动植物截然不同的印记。然而，针对寄生于北极-高山分布宿主的病原体的相关研究却极为匮乏。为此，本研究针对一种寄生于北极-高山植物的真菌，探究了其地理分布范围与种群结构。本研究共检视了1437份无茎蝇子草（Silene acaulis）的标本馆标本（herbarium specimen），发现花药黑粉菌（anther smut）病原体雪灵芝黑粉菌（Microbotryum silenes-acaulis）在宿主的全部地理分布范围内均有存在。研究显示，在纬度更高的北部区域以及宿主种群密度更低的采样点，花药黑粉病的发病率显著更高，这表明环境因素和/或宿主种群统计结构对该病原体的分布具有重要调控作用。本研究利用7个微卫星标记（microsatellite marker），对195份新近采集的雪灵芝黑粉菌（M. silenes-acaulis）样本进行遗传分析，结果显示其可划分为三大主要遗传簇（genetic cluster），分别对应北美、北欧与南欧区域，这大概率与末次冰期期间不同避难所内的种群分化相关。北欧地区较低的遗传多样性，暗示该区域的种群是在冰期后从南部避难所向北迁徙定植而来。综上，本研究结合标本馆调查与种群遗传学分析，首次揭示了气候与环境因素对北极-高山分布植物病原体的影响机制。