Transmission of branch-inducing phytoplasma PoiBI from poinsettia (Euphorbia pulcherrima) to crown-of-thorns (E. milii)

Abstract

Phytoplasma PoiBI is responsible for free branching in poinsettia (Euphorbia pulcherrima Wild. ex. Klotzsch). In this study, PoiBI was transmitted by dodder from poinsettia to crown-of-thorns (E. milii Des Moulins) in one out of ≈100 attempts, whereas grafting transmission was unsuccessful. PoiBI was shown to be viable in E. milii, as it was detected in the recipient plant and in its cuttings over 1.5 years by polymerase chain reaction. It was shown that PoiBI induces free branching in E. milii as well as in poinsettia. Smaller leaves, reduced growth rates, and delayed flowering were other effects of PoiBI infection.