Redondo Miguel A, Boberg Johanna, Olsson Christer H B, Oliva Jonàs
First, second, and fourth authors: Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, 750 07 Uppsala, Sweden; and third author: Department of Biological and Environmental Sciences, Gothenburg University, Box 461, 405 30 Göteborg, Sweden.
Phytopathology. 2015 Sep;105(9):1191-7. doi: 10.1094/PHYTO-01-15-0020-R. Epub 2015 Aug 24.
During the last century, the number of forest pathogen invasions has increased substantially. Environmental variables can play a crucial role in determining the establishment of invasive species. The objective of the present work was to determine the correlation between winter climatic conditions and distribution of two subspecies of the invasive forest pathogen Phytophthora alni: P. alni subspp. alni and uniformis killing black alder (Alnus glutinosa) in southern Sweden. It is known from laboratory experiments that P. alni subsp. alni is more pathogenic than P. alni subsp. uniformis, and that P. alni subsp. alni is sensitive to low temperatures and long frost periods. By studying the distribution of these two subspecies at the northern limit of the host species, we could investigate whether winter conditions can affect the geographical distribution of P. alni subsp. alni spreading northward. Sixteen major river systems of southern Sweden were systematically surveyed and isolations were performed from active cankers. The distribution of the two studied subspecies was highly correlated with winter temperature and duration of periods with heavy frost. While P. alni subsp. uniformis covered the whole range of temperatures of the host, P. alni subsp. alni was recovered in areas subjected to milder winter temperatures and shorter frost periods. Our observations suggest that winter conditions can play an important role in limiting P. alni subsp. alni establishment in cold locations, thus affecting the distribution of the different subspecies of P. alni in boreal regions.
在上个世纪，森林病原体入侵的数量大幅增加。环境变量在决定入侵物种的定殖方面可能起着关键作用。本研究的目的是确定冬季气候条件与入侵森林病原体木麻黄疫霉两个亚种分布之间的相关性：木麻黄疫霉亚种木麻黄疫霉和同型疫霉在瑞典南部致使黑桤木（Alnus glutinosa）死亡。从实验室实验可知，木麻黄疫霉亚种木麻黄疫霉比木麻黄疫霉亚种同型疫霉更具致病性，且木麻黄疫霉亚种木麻黄疫霉对低温和长霜冻期敏感。通过研究这两个亚种在寄主物种北界的分布情况，我们可以调查冬季条件是否会影响木麻黄疫霉亚种木麻黄疫霉向北扩散的地理分布。对瑞典南部的16条主要河流系统进行了系统调查，并从活跃病斑处进行了分离培养。所研究的两个亚种的分布与冬季温度和重霜期持续时间高度相关。虽然木麻黄疫霉亚种同型疫霉覆盖了寄主的整个温度范围，但木麻黄疫霉亚种木麻黄疫霉是在冬季温度较温和、霜冻期较短的地区分离得到的。我们的观察结果表明，冬季条件在限制木麻黄疫霉亚种木麻黄疫霉在寒冷地区定殖方面可能发挥重要作用，从而影响木麻黄疫霉不同亚种在北方地区的分布。
