Interaction of tobacco etch or tobbaco vein mottling virus and ozone on biomass changes in burley tobacco

Abstract

Burley tobacco is susceptible to several different types of virus diseases that suppress plant growth and development. Two viruses, tobacco etch virus (TEV) and tobacco vein mottling virus (TVMV), are particularly damaging to burley. Burley tobacco cultivars resistant to these two viruses are currently being developed. Some of these cultivars also show differential sensitivity to ozone (O 3). Recent field observations have suggested that burley tobacco infected with TEV and TVMV was more sensitive to O 3 than non-virus-infected tobacco. Experiments were designed to identify interactions between O 3 and each of the two virus diseases. Three cultivars, Burley 21, Burley 49, and Greeneville 131, which were differentially sensitive to O 3 and both virus diseases, were grown in a charcoal-filtered greenhouse environment. Tobacco plants of each cultivar were inoculated with TEV or TVMV, and virus infected and virus-free plants were exposed to 0·0, 0·05, 0·2, and 0·4 ppm O 3 (1 ppm of O 3 is equivalent to 1960 μg m −3), 3h day −1, 5 days week −1 for 3 weeks in continuous-stirred tank reactor exposure chambers in the greenhouse. Exposures were begun after systemic virus symptoms were expressed in inoculated plants. The suppression of lead and stem dry weight by increasing O 3 concentrations was less in TEV-infected burley cultivars than in noninfected burley cultivars. Tobacco vein mottling virus infection enhanced biomass suppression by O 3 on Burley 21 and on Greeneville 131, but not on Burley 49. Thus, the interactions with O 3 were dependent on specific virus-cultivar combinations.