Pre- and post-embedding immunogold labeling and electron microscopy in plant host tissues of three antigenically unrelated MLOs: primula yellows,tomato big bud and bermudagrass white leaf

Methods are described for pre- and post-embedding immunogold labeling of mycoplasmalike organisms (MLOs) in thin sections of infected plants. Antisera against primula yellows (PY), tomato big bud (TBB) and bermudagrass white leaf (BGWL) MLOs, and a monoclonal antibody (mab) against PY were tested with the three serologically unrelated MLOs. Labeling was specific for each MLO and was localized to the outer surface of the MLOs. The antisera performed well in both pre- and post-embedding experiments; the mab reacted well in pre-embedding conditions but gave no labeling with post-embedding. Glutaraldehyde fixation reduced levels of labeling in post-embedding conditions. The results show that these techniques can be used to differentiate MLOs reliably, and extend the usefulness of electron microscopy in this area.