Tobacco mosaic virus infection in leaf tissue of nicotiana tabacum L. CV. ‘Little Turkish’

Abstract

Many types of plant tissues are subject to infection by the tobacco mosaic virus (TMV) and TMV apparently is not selective in terms of a particular cellular site of localization (Esau and Cronshaw, 1967). There have been several reports on the presence of TMV in leaf tissue of Nicotiana (Henry, 1980; Esau and Cronshaw, 1967). The effect of TMV on leaf tissue of Nicotiana tabacum L. cv. ‘Little Turkish’ is discussed in terms of ultrastructural appearance and sites of TMV localization within the cellular areas of infection.Twelve-week-old tobacco plants were treated with Carborundum (dusting), followed by subsequent inolulation with a purified solution of TMV. Experimental and control plants (non-TMV-treated) were kept under similar light environments and exposed to a temperature of 23 ± 1°C in the day and 20 ± 2°C at night. Leaf tissue portions were excised from experimental and control plants respectively and prepared for ultrastructural examination (Henry, 1980).TMV infection appears to cause excessive swelling in chloroplasts (Figs.1–2), in addition to enlargement of plastoglobuli (Figs. 1–2). Starch bodies appear enlarged and separated from other elements of the chloroplastsstroma (Figs. 1–2). Chloroplast lamellae and cell walls both appear to be swollen and distorted in TMV infected tobacco leaf tissues (Figs. 1–2).To summarize, TMV infection in tobacco leaf tissue causes a generalized distortion and swelling of the tissue, particularly cell walls, chloroplasts, plastoglobuli, starch bodies and chloroplastslamellae (Figs. 1–2). It is suggested that TMV infection, due to its comprehensive invasion of the cellular integrity of the tissue, is thereby able to exert distinct and destructive effects on the leaf tissue cellular metabolism. Also, the results of the present study lend support to the suggestion of Betto et al. (1972) that the chloroplast may be possible site of TMV multiplication in virus infected tisue.