Experimental systems to monitor the impact of transgenic corn on keystone soil microorganisms

Summary

Risks and benefits of transgenic crop plants should be evaluated not only by assessing pollen flow, but also by considering soil persistence of transgenic products, such as Bt toxins, which can accumulate in the soil and remain active for a long time. Moreover, transgenic plants are often ploughed under as crop residues, representing a potential hazard for non-target arbuscular mycorrhizal (AM) fungi, a group of beneficial plant symbionts fundamental for soil fertility. In this study we monitored the effects of transgenic corn plants (Bt 11 and Bt 176) and their residues on AM fungal growth and root colonization ability. Both transgenic plants decreased mycorrhizal colonization and Bt 11 plant residues negatively affected mycorrhizal establishment by indigenous endophytes, four months after their incorporation into soil.