A phytoplasma was discovered in diseased specimens of f ield-grown hortensia (Hydrangea spp.) exhibiting typical phyllody symptoms. PCR amplification of DNA using phytoplasma specific primers detected phytoplasma DNA in all of the diseased plants examined. No phytoplasma DNA was found in healthy hortensia seedlings. RFLP patterns of amplified 165 rDNA differed from the patterns previously described for other phytoplasmas including six isolates of foreign hortensia phytoplasmas. Based on the RFLP, the Japanese Hydrangea phyllody (JHP) phytoplasma was classified as a representative of a new subgroup in the phytoplasma 165 rRNA group I (aster yellows, onion yellows, all of the previously reported hortensia phytoplasmas, and related phytoplasmas). A phylogenetic analysis of 16s rRNA gene sequences from this and other group I phytoplasmas identified the JHP phytoplasma as a member of a distinct sub-group (sub-group Id) in the phytoplasma clade of the class Mollicutes. The phylogenetic tree constructed from 165 rRNA gene sequences was consistent with the hypothesis that the JHP phytoplasma and its closest known relatives, the Australian grapevine yellows (AUSGY), Phormium yellow leaf (PYL), Stolbur of Capsicum annuum (STOL) and Vergilbungskrankheit of grapevine (VK) share a common ancestor. The unique properties of the DNA from the JHP phytoplasma clearly establish that it represents a new taxon, Candidatus Phytoplasma japonicum '.

Tomato leaf mold caused by Passalora fulva was found on two tomato varieties carrying the Cf-9 gene in Japan, in 2007. The isolates obtained from Chiba and Fukushima were identified as race 4.9.11, and those from Gunma were races 4.9 or 4.9.11. This is the first report in Japan of tomato leaf mold caused by P. fulva strains that can overcome the Cf-9 gene.

In 1994 and 1995, hydrangea phyllody occurred in Tochigi, Shizuoka and Oita Prefectures, Japan.The affected plants (Hydrangea macrophylla and H. serrata) showed phyllody and proliferation of flower organs, as well as stunting and dieback. Electron microscopy revealed the presence of phytoplasmas in the phloem sieve elements of affected sepals and leaves. The phytoplasmas were transmitted to healthy Catharanthus roseus by graft inoculation. Using primers for 16S rDNA by polymerase chain reaction (PCR), DNA fragments of 1.3 and 0.75kbp were amplified in DNA samples extracted from affected hydrangeas but not in those extracted from healthy plants. This is the first report on the occurrence of hydrangea phyllody in Japan.

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