The amount and distribution of poinsettia branch-inducing phytoplasma in poinsettia.

摘要

The relative distribution of poinsettia branch-inducing phytoplasma (PoiBI) in different tissues and in different parts of poinsettia plants was quantified using the comparative Ct method and a new developed TaqMan real-time PCR assay. Five samples were analysed from each of 6 different nodes equally distributed along the height of the plant. Also, samples from the top of the plant, from the stem base and the primary and secondary roots were studied. The quantitative real-time PCR test proved to be a very sensitive test. Highest phytoplasma levels was found in the bark samples, while the stem core samples contained little or no detectable phytoplasma. The lack of accumulation of phytoplasma in sink tissues indicated restricted phloem translocation of PoiBI. There were large plant-to-plant variations in PoiBI content and further studies including more plants will be needed in order to reveal the general distribution of PoiBI and its possible correlation to branching in poinsettia..