Studies on life cycle and ecology of spruce rusts in the central mountainous region of Japan

云杉锈病是欧洲和北美云杉属植物的毁灭性病害，在日本也经常发生。然而，致病真菌的生命周期和生态学仍然大多不确定。通过田间调查、形态观察和接种试验，研究了日本中部山区云杉锈菌的生活史和生态学。通过野外调查和分类学鉴定，确定高山杨和白泽杨上的锈病为冷杉叶锈菌（Escheromyxa abietis），而条斑杨上的锈病为琥珀叶锈菌（C. succinea）。此外，在中部山区的几个地点还发现了一种新的锈菌寄主--为阐明琥珀绒螯蟹群体的遗传结构，对rDNA中的IGS 1区进行了PCR-RFLP分析。Yastugatake山，富士3-gome和富士Gotenniwa的异株种群中检测到遗传变异，而在富士5-gome和富士Oniwa的同株种群中没有遗传多样性。这些结果表明，琥珀锦鸡儿可能是由异花同株和雌雄同株的种群组成的，这些种群在遗传上相互分化。

The spruce rusts, which are known as destructive disease of Picea plants in Europe and North America, have often been recorded to occur in Japan. However, the life cycle and ecology of the causal fungi remain mostly uncertain. In the present study, field surveys, morphological observations and inoculation experiments were carried out to clarify the life cycle and ecology of spruce rust fungi in the central mountainous region of Japan. From field surveys and taxonomic examinations, the rust occurred on P.koyamae and P.shirasawae was identified as Chrysomyxa abietis, and the rust on P.jezoensis var.hondoensis was identified as C.succinea. Additonally, a new Chrysomyxa rust host-alternating between P.polita and Rhododendron dilatatum was found in several locations of the central mountainous region. PCR-RFLP analysis of IGS1 region in rDNA was carried out to clarify the genetic structure of C.succinea populations. Genetic variations were detected in heteroecious populations in Mt.Yastugatake, Fuji 3-gome and Fuji Gotenniwa, whereas there was no genetic diversity in autoecious populations in Fuji 5-gome and Fuji Oniwa. These results suggest that C.succinea may be composed of heteroecious and autoecious populations which are genetically differentiated from each other.