First report of ‘ Candidatus Phytoplasma asteris’ infecting hydrangea showing phyllody in Japan

Phytoplasma-induced floral malformations such as virescence, phyllody, and proliferation were observed on hydrangeas in Gunma Prefecture, Japan. Phylogenetic analyses based on 16S rRNA, secY , groEL , and amp gene sequences indicated that the affected hydrangea plants were associated with phytoplasmas belonging to ‘Candidatus Phytoplasma asteris’, but not to ‘ Ca. P. japonicum’, which occurs in hydrangeas showing phyllody in Japan. This is the first molecular evidence of an association of ‘ Ca. P. asteris’ with hydrangea plants in Japan.