Phytoremediation of arsenate contaminated soil by transgenic canola and the plant growth-promoting bacterium Enterobacter cloacae CAL2

It was previously observed that transgenic tomato plants that express the Enterobacter cloacae UW4 1-aminocyclopropane-1-carboxylate (ACC) deaminase (EC 4.1.99.4) gene, and thereby produce lower levels of ethylene, were partially protected from the deleterious effects of six different metals. However, since tomato plants are unlikely to be utilized in the phytoremediation of contaminated terrestrial sites, transgenic canola (Brassica napus) plants that constitutively express the same gene were generated and tested for their ability to proliferate in the presence of high levels of arsenate in the soil and to accumulate it in plant tissues. The ability of the plant growth-promoting bacterium E. cloacae CAL2 to facilitate the growth of both non-transformed and ACC deaminase-expressing canola plants was also tested. In the presence of arsenate, in both the presence and absence of the added plant growth-promoting bacterium, transgenic canola plants grew to a significantly greater extent than non-transformed canola plants.