ARS | Publication request: Effects of Lead (Pb) on the Systemic Movement of RNA Viruses in Tobacco (Nicotiana tabacum var. Turkish)

Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 2011
Publication Date: March 15, 2011
Repository URL: http://handle.nal.usda.gov/10113/53889
Citation: Alkhatib, R., Creamer, R., Lartey, R.T., Ghoshroy, S. 2011. Effect of lead (Pb) on the systemic movement of RNA viruses in tobacco (Nicotiana tabacum var. Turkish). Plant Cell Reports. 30:1427–1434.

Interpretive Summary: In this research, we examined the effect of different concentrations of lead on the systemic movement of four RNA viruses in tobacco plants. The plants were grown mineral nutrient solutions in water for six days. The solutions were supplemented with five concentrations of lead nitrate at 10 µM, 15 µM, and 50 µM, 100 µM and 0.0 as control. The plants were then inoculated with four different RNA viruses namely, Tobacco mosaic virus (TMV), Turnip vein-clearing virus (TVCV), Potato virus X (PVX), and Tobacco etch virus (TEV), with different mechanisms of cell-to-cell movement. Two weeks after inoculation, lower and upper leaves of each treatment were examined for the presence of viral coat protein. The results demonstrated presence of viral coat proteins in the upper leaves of all lead treated plants which were inoculated with TMV, PVX and TEV. These observations were further confirmed by TEM images and western blot test. TVCV inoculated plants, on the other hand did not show evidence for presence of viral particles in the upper leaves of plants in solutions containing 10 µM or 15 µM lead nitrate. However, TVCV viral particles were detected in upper leaves of plants with high concentrations of lead nitrate at 50 µM or 100 µM. Further examination of plants treated with 10 µM or 15 µM lead nitrate showed callose accumulation level similar to the control plants. The plants treated with 100 µM, however showed less callose when compared to the control plants. Our finding suggests that non-toxic concentrations of lead nitrate may trigger the production of cellular factors besides callose that interfere with systemic movement of TVCV.

Technical Abstract: Effect of different lead (Pb) concentrations on the systemic movement of RNA viruses was examined in tobacco plants. Prior to inoculation, plants were grown hydroponically for six days in Hoagland's solution supplemented with five concentrations of lead nitrate [Pb(NO3)2]:0.0 (control), 10 uM, 15 uM, and 50 uM and 100 uM. Four different RNA viruses with different cell-to-cell movement were used. Two weeks after inoculation lower and upper leaves of each treatment were harvested and examined for the presence of viral coat protein. In plants inoculated with tovacco mosaic virus (TMV), potato virus X(PVX), and tobacco etch virus (TEV), TEM images and western blot assays confirmed the presence of viral coat proteins in the upper leaves of all lead treatment. However, in plants inoculated with turnip vein-clearing virus (TVCV), no signs of viral disease were detected in the upper leaves of plants treated with 10 uM or 15 uM lead nitrate. In contrast, plants treated with high concentrations of lead nitrate (50 uM or 100 uM) showed disease symptoms in their upper leaves. This suggests that an inhibitory mechanism of the systemic movement was triggered by non-toxic concentraions of lead nitrate.