Effect of Plant Hormones on Tobacco Mosaic Virus Concentration in Tobacco Tissue Culture

Tobacco mosaic virus (TMV) concentrations in tobacco callus tissues grown on the media containing cu-naphthaleneacetic acid (NAA) and kinetin at different concentrations were assayed periodically during successive cultures. Tobacco callus originally raised from the TMV-infected tobacco stem became green and compact when serially cultured on the medium containing lower concentration (0.01-o. 1 mg/l) of NAA or higher concentration (2mg/l) of kinetin. Translucent and soft callus was obtained at higher concentration (l-40 mg/l) of NAA or lower concentration (O-O. 2 “g/l) of kinetin. Microscopic observations of the thin sectioned callus tissues revieled that the green colored compact tissue was composed of the closely associated small cells and many tracheid-like structures, while in the translucent and soft tissue, large cells were roughly arranged showing less association and no tracheidlike structure was found. TMV was maintained at high concentration in the compact callus during successive cultures, however, it was no longer detected beyond the third generation (90 days) in the translucent soft callus grown under the optimum hormone balances. Since both hormones do not have direct inactivation effect on TMV, the results suggest that TMV multiplication in the callus tissue closely corresponds with the cell arrangement of the tissue, which is considerably affected by hormone balances in the media.