A study was conducted, under laboratory conditions, to evaluate lead uptake and distribution in tobacco plantlets in vitro exposed to the heavy metal and to reveal possible differences in the response to lead exposure, depending on variety and/or type of tobacco. Seeds of N. tabacum varieties Burley IST Bu23, Burley IST G94-2, Bright IST G19, Bright IST G 165, Perustitza IST Pr61 and Perustitza IST P2B, were aseptically germinated on solidified Murashige & Skoog medium (MS). Two-week-old seedlings were transferred and cultured in semisolidified MS for 3 weeks. Then the plantlets were cultured in liquid MS for a further 2 weeks. At this stage the plants were exposed to lead nitrate solutions for 10 days according to a randomized block experimental design with three replications and four lead nitrate rates (Pb0 = distilled water, Pb1 = 0.01 mM Pb(NO₃₎₂, Pb2 = 0.1 mM Pb(NO_3)2; Pb3 = 1 mM Pb(NO₃₎₂. As regards dry matter weight per plant, no difference between lead nitrate rates was observed. Lead chemical analyses, by Atomic Absorption, were performed on upper leaves, lower leaves, stems and roots. We observed that the lead content increased as the lead exposure rate increased, for all plant parts and for all the varieties examined. For all treatments the highest lead contents were registered in roots while the lowest in upper leaves, for each exposure level and variety. The results obtained highlighted a great potential for lead uptake by all tobacco lines assayed. A significant effect of variety on lead content was observed.

* This research was carried out with financial support of the Commission of the European Community, Tobacco and Information and Research Fund, project 96/T/35 "Monitoring and minimizing heavy metal contents in tobacco" . It does not necessarily reflect the views of the Commission and in no way anticipates its future in this area.