ISHS Acta Horticulturae 164: VI International Symposium on Virus Diseases of Ornamental Plants
LIGHT MICROSCOPY OF PLANT VIRUS INDUCED INCLUSIONS |
| Authors: | R. G. Christie, John R. Edwardson |
| Abstract:
Plant virus inclusions are intracellular structures resulting from virus infection. These structures may contain scattered and aggregated virus particles, as well as other virus-related nucleic acids. Certain types of inclusions may consist almost entirely of virus induced non-capsid protein, such as the cylindrical (pinwheel) inclusions of the potyvirus group. Modified host cell organelles can also be present. In many cases the above mentioned components combine to form massive, complex inclusions. The inclusions differ from the surrounding cytoplasm and organelles in their staining reactions and structural appearance as Visualized by light and electron microscopy. Virus inclusions have been detected in the cytoplasm, vacuoles, and nuclei of infected cells. In some cases they have been found within cytoplasmic organelles or associated with cell wall abnormalities. Inclusions induced by certain viruses are found associated with specific tissues, such as the phloem or meristems. Information about the type(s) of inclusion present, their intracellular and tissue location, combined with their staining properties can be useful in the classification and diagnosis of viruses (Edwardson and Christie, 1978, Hamilton et al., 1981). Inclusions are not static, but go through developmental stages. Their appearance may change as they increase in size and complexity although such changes always follow a definite pattern. The host, as well as environmental conditions can influence inclusion expression. This influence does not alter the basic inclusion types, but rather 1) the time the inclusions first appear, 2) the rate at which the various stages of development occur, 3) the ultimate size or stage of development attained, and 4) the total number of inclusions present (i.e., the distribution in various tissues). Under favorable conditions, inclusions reach a stage of maximum expression or | |
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