Influence of arbuscular mycorrhiza on the growth and cadmium uptake of tobacco with inserted metallothionein gene

The effect of arbuscular mycorrhiza (AM) on the growth and cadmium (Cd) uptake of transgenic tobacco with increased ability to accumulate Cd was assessed. The transgenic tobacco bearing yeast metallothionein gene combined with a polyhistidine cluster was compared to non-transgenic tobacco in two pot experiments with different substrates - soil and river sand - amended or unamended with Cd. The development of AM did not differ between the transgenic and non-transgenic plants in either experiment. AM improved the phosphorus nutrition of the tobacco plants in both experiments, their biomass production, however, was increased only in sand, while in soil, it was lower or remained unchanged compared to non-mycorrhizal plants. AM decreased the Cd uptake of the tobacco plants per unit of shoot biomass in both experiments and decreased the Cd accumulation in the shoots of the transgenic tobacco relatively to the non-transgenic tobacco. It is concluded that AM symbiosis is likely to influence the heavy metal (HM) accumulation ability of plants targeted by transgenosis. Thus, AM must be considered in testing the transgenic plants as it can change the relative performance of the transgenic plants compared to the non-transgenic plants. (C) 2005 Elsevier B.V All rights reserved.