Do genetically modified plants affect adversely on soil microbial communities?

With the increase in the number of commercial applications and larger cultivation areas of genetically modified (GM) plants, their biosafety for soil microorganisms has become a controversial issue. The effects on the diversity and abundance of soil microorganisms are important components of evaluation of the biosafety risks of GM plants. So far, no definite conclusions have been drawn about whether GM plants can negatively affect soil microorganisms. In this review, we discuss the advances that have been made in recent years in the research into the effects of GM plants on soil microbial communities. It has been argued that foreign gene products that are released from the residue of GM plants into soil by root exudation may affect soil microbial communities. Moreover, foreign genes may change the genetic and functional properties of soil microorganisms via horizontal transfer. The advantages and disadvantages of various detection technologies-from classical culture-dependent methods to modern molecular protocols-are reviewed here. To accurately and comprehensively evaluate the effects of GM plants on microorganisms, we discuss the factors that should be considered in the assessment of risks of GM plants for soil microorganisms (e.g., foreign proteins, marker genes, plant varieties, and environmental factors), as well as the problems and prospects related to biosafety assessment platforms for GM plants.