Electron microscopic study of Verticillium dahliae Kleb. as a pathogen of tobacco (Nicotiana Tabacum L.)

Summary

Green, chlorotic, and necrotic tissue from leaves of tobacco plants naturally infected with Verticillium dahliae were prepared for study with the electron and light microscopes.

Isolations were made and the fine structure of the fungus compared in vivo and in vitro. It was found to be similar in both environments.

Degenerating hyphae, intrahyphal hyphae, endospores, and structure of the microsclerotia were observed in cultured isolates.

The fungus was seen in the xylem elements, but not in the adjacent parenchymatous tissue. Unidentified bodies were observed in the intercellular spaces of green and chlorotic mesophyll tissue and within chlorotic and necrotic mesophyll cells. In many cases these bodies were in the process of passing through the cell walls.

Increased site and number of plastoglobuli were observed in chloroplasts just before their degeneration and this change may be associated with chlorosis.