Detection and identification of a new phytoplasma associated with periwinkle leaf yellowing disease in Taiwan

摘要

A new leaf yellowing disease was observed on periwinkle (Catharanthus roseus) in Taiwan in 2005. Sequence analysis of a 1.8 kb region of 16S rDNA, 16S-23S intergenic spacer region and partial 23S rDNA revealed that the periwinkle leaf yellowing (PLY) disease was associated with a phytoplasma from the 16SrI group. In addition, five cultivated plants including chrysanthemum (Chrysanthemum sp.), cosmos (Cosmos bipinnatus), torenia (Torenia fournieri), Persian violet (Exacum affine), and cucumber (Cucumis sativus), and one weed, goosegrass (Eleusine indica) were identified as host plants of this phytoplasma. Leafhoppers, Macrosteles orientalis, Cicadulina bipunctella, Phlogotettix cyclops and Balclutha sp., were identified as potential insect vectors due to the positive results in PCR detection. The name, "Candidatus Phytoplasma asteris" strain PLY, is proposed for this new phytoplasma. The in silico restriction fragment length polymorphism analysis of the Fn2R2 region sequence showed that the periwinkle leaf yellowing phytoplasma is closest to the 16SrI-B subgroup and may be a new 16SrI subgroup. Transmission experiments with field-collected M. orientalis and C. bipunctella indicated that both leafhoppers can transmit the PLY phytoplasma to healthy periwinkle plants. This work is the first description of a new 16SrI subgroup phytoplasma in Taiwan.