Studies on invasional or importational routes of tree-disease pathogens in East Asia

分析了树植原体的核糖体DNA序列，并研究了它们与东亚近缘种的关系。在日本的枳木丛枝病中发现了枣疯病，在韩国发现了一种表现矮化症状的女贞病和枣疯病。它们的rDNA序列均具有同源性。在日本的杜英（Elaeocarpus sylvestris）中发现一种与杜英黄化植原体（Elaeocarpus yellows phytoplasma）关系密切的种。此外，在台湾还发现了其他几种宿主，如台湾粉蝶。16S rDNA的差异几乎没有。在ITS域中，日本病原体是相同的，但台湾病原体表现出个体差异。这些结果表明，病原菌在台湾的分布时间比在日本要长得多。所检测的卷镰孢分离物在组蛋白H3上具有完全相同的DNA序列。对benA、TEF和IGS的数据集进行最大简约分析。日本分离株分为两组。其中1株与大部分韩国分离物及部分美国和南非分离物组成一个亲缘关系近的类群。其余的韩国、美国和南非分离株也形成了另一个系统发育群。有人认为，该病原体是作为克隆传入日本或韩国的，并逐渐在各个地点分化。至于枣，从韩国进口到日本的记录很少。由于检查是通过对活树的表面观察进行的，因此可以避免无菌感染。建议将PCR技术应用于植物检疫。

Ribosomal DNA sequences of tree-phytoplasmas were analyzed and examined their relationship with closely related East Asian species. 'Candidatus P.ziziphi' was detected in Hovenia witches'-broom in Japan and a privet disease showing dwarf symptoms, and jujube witches'-broom, were found in Korea. All their rDNA sequences were homologous. A species closely related to the Elaeocarpus yellows phytoplasma was detected in Elaeocarpus sylvestris, E.japonicus in Japan. In addition, several other hosts e.g. Pieris taiwanensis, were detected in Taiwan. They showed almost no differences in 16S rDNA. In the ITS domain, the Japanese pathogens were identical, but the Taiwanese pathogens exhibited individual differences. These results suggest that the distribution of the pathogen would take much longer in Taiwan than in Japan.DNA sequences of some gene regions were analyzed on the pathogen of pitch canker disease of pines. Fusarium circinatum isolates examined have completely the same DNA sequence on Histone H3. Maximal Parsimony analyses were conducted on the data set of benA, TEF and IGS. Japanese isolates were divided into two groups. One of them formed one phylogenetically-related group together with most of Korean isolates and a part of American and South African isolates. The rest of Korean, American and South African isolates also formed another phylogenetic group. It was suggested that the pathogen was introduced as a clone into Japan or Korea and gradually became diverged at the individual locations.Plant-quarantine systems in peripheral countries were examined. As for the Zizyphus jujube, there were a few records of importation from South Korea to Japan. As the inspections are made by surface-observation on living-trees, symptomless infections are escapable. We recommend the adaptation of PCR for plant-quarantine.