Dodder transmission of phytoplasmas.

Transmission of phytoplasmas from naturally infected plant host species using the parasitic plant Cuscuta spp. (dodder) to Catharanthus roseus (Madagascar periwinkle) is an effective way to maintain a wide range of phytoplasmas for further research. Here, we describe transmission via dodder from an infected medicinal plant Rehmannia glutinosa var. purpurea and from a symptomatic redcurrant plant (Ribes spp.) to C. roseus indicator plants using a "stable bridges" method. In both cases, typical symptoms of phytoplasma disease on periwinkle plants were obtained: virescent flowers with an increased number of axillary shoots and smaller leaves after transmission from R. glutinosa, and greening petals (virescence) after transmission from Ribes spp. Phytoplasmas could be detected in donor and recipient plants by electron microscopy and by polymerase chain reaction (PCR) assays using universal phytoplasma primer pairs. Restriction fragment length polymorphism analyses of PCR fragments can also be used to confirm the identity of the phytoplasmas from donor and recipient plants.