Epidemics of Scots pine blister rust, caused by Cronartium pini, have become an increasing problem in northern Finland and Sweden. The biology of the rust fungus is complex, with two different life cycle forms that cannot be morphologically distinguished, and it is unclear to what extent the two forms contribute to the epidemics. Genetic structure of fourteen populations of C. pini were investigated in Fennoscandia. Distinction between the two life cycle forms, a heteroecious and an autoecious one, was made by determining zygosity using microsatellite markers, and AFLP markers were developed to analyse population genetic relationships. The results showed that the two life cycle forms are clearly differentiated and occur in separate populations. Within the life cycle forms, geographic differentiation was evident, probably due to restricted gene flow as well as connection with different alternating hosts. The host-alternating form dominated in the epidemic regions in northern Fennoscandia. Implications for silvicultural practices are discussed.

樟脑孢子虫引起的苏格兰松树水疱锈病的流行已成为芬兰北部和瑞典日益严重的问题。锈菌的生物学很复杂，有两种不同的生命周期形式，无法从形态上加以区分，目前尚不清楚这两种形式在多大程度上促进了流行。松树十四个种群的遗传结构在芬诺斯坎迪亚进行了调查。通过使用微卫星标记确定接合性来区分两种生命周期形式，即异性和自噬，并开发了AFLP标记来分析种群遗传关系。结果表明，两种生命周期形式有明显区别，并分别出现在不同的人群中。在生命周期形式中，地理分化是明显的，这可能是由于基因流受限以及与不同交替宿主的联系所致。寄主交替形式在北部芬诺斯坎迪亚的流行地区占主导。讨论了营林实践的含义。