Expression of selected genes involved in cadmium detoxification in tobacco plants grown on a sulphur-amended metal-contaminated field

▶ Expression of selected genes involved in cadmium detoxification in tobacco plants grown on a sulphur-amended metal-contaminated field. ▶ Increased Cd concentrations in tobacco grown in a Cd contaminated sulphur treated field are associated with up-regulation of putative Cd transporters ( NtMRP_a, NtATM_a, and NtPDR_a) and genes involved in sulphur assimilation ( NtSultr_a, NtAPR_a, and NtAPR_b) in root tissues. This is consistent with previous studies using hydroponics or agar. Our results indicate that hydroponic or agar experiments are useful predictors of effects that may be expected in the field. We investigated the effect of a Cd solubilising soil treatment on the expression of genes regulating Cd uptake and detoxification in field-grown tobacco plants. Tobacco plants were grown on a heavy-metal contaminated soil to which elemental sulphur was applied to increase the phytoextraction of Cd. The expression of tobacco gene homologues for A. thaliana MRP3, PDR8, ATM3, Sultr1, LAST, APR2, APR3, GSHI, GSHII, and NAS3 was assayed by qualitative RT-PCR. Increased root and shoot Cd concentrations were associated with up-regulation of the putative Cd transporters and the genes involved in sulphur assimilation in root tissues. This is consistent with previous studies using hydroponics. However, unlike the previous studies, most of the genes tested in the leaves were unaffected by Cd concentration. These differences may be due to the more complex stress situation that plants experienced here under field conditions. Moreover, unlike in hydroponic studies, our plants were sampled at maturity and not in the seedling stage. Our results indicate that hydroponic or agar experiments are useful predictors of effects that may be expected in the field. However, there is a need for studies investigating gene expression in response to multiple stresses representative for field conditions at later developmental stages.