Cadmium tolerance in tobacco cell culture and its relevance to temperature stress

Growth of unselected tobacco (Nicotiana tabacum W38) cell suspension cultures was reduced by 50–200 M cadmium (Cd) in the culture medium and cells were killed by 400 M Cd. Tolerance to Cd was increased either by using rapidly growing cells or by culturing cells at higher densities. Cell lines tolerant to 2 mM Cd were established by progressively elevating levels of Cd in the culture medium. The Cd tolerance was not due to differences in uptake between unselected and Cd-tolerant cell lines, and the tolerance to Cd was not lost during long term culture in the absence of Cd. Cd-tolerant cells also showed higher tolerance to heat shock (37.5°C, 2–8 hours) and cold treatments (4°C, 1–7 days) than the unselected cells.