Transmission Electron Microscopic Methods for Plant Virology

Transmission electron microscopy (TEM) is an important tool for observing the ultrastructure of plant virions and their host cells. The two main applicable TEM technologies used in plant virology are negative staining and ultrathin section. Negative staining is mainly used to observe the high-resolution structure of virus particles under a transmission electron microscope. Sample preparation for negative staining is convenient and fast, making it suitable for studying the virions in crude sap or purified solution. A modification of negative staining, by combining immunological reaction, named as technique of immuno-negative staining, is used to enrich or identify viruses. Ultrathin section is used for ultrastructural cytopathological studies in the virus-infected host cells, including the morphology of virus particles, the structure of viral induced inclusion bodies, the subcellular distribution of virions and the structural alteration of the host cell induced by viral infection. Such information is valuable to analyze the behavior of virus in replication, assembly, and intercellular transportation, and thus to understand the viral infection cycle. The present chapter describes the operation details of negative staining and ultrathin section TEM.