Arbuscular Mycorrhiza Decreases Cadmium Phytoextraction by Transgenic Tobacco with Inserted Netallothionein

Pot trials tested the effect of arbuscular mycorrhiza (AM) on the phytoextraction efficiency of transgenic tobacco with increased ability to tolerate and bioaccumulate cadmium. Tobacco plants bearing yeast metallothionein combined with a polyhistidine cluster were compared with non-transgenic plants of the same variety at four Cd doses in soil, inoculated or not with two isolates of an AM fungus. Inoculation improved growth of both plant types and reduced Cd levels in shoots and root to shoot translocation. AM reduced the phytoextraction efficiency of transgenic plants and increased that of non-transgenic plants at Cd levels in soil inhibitory to tobacco growth.