Effects of transgenic plants on soil microorganisms

Abstract

The rapid development of agricultural biotechnology and release of new transgenic plants for agriculture has provided many economic benefits, but has also raised concern over the potential impact of transgenic plants on the environment. Considerable research has now been conducted on the effects of transgenic plants on soil microorganisms. These effects include unintentional changes in the chemical compositions of root exudates, and the direct effects of transgenic proteins on nontarget species of soil microorganisms. Most studies to date suggest that transgenic plants that have been released cause minor changes in microbial community structures that are often transient in duration. However, due to our limited knowledge of the linkage between microbial community structure and function, more work needs to be done on a case-by-case basis to further evaluate the effects of transgenic plants on soil microorganisms and soil ecosystem functions. This review summarizes the results of a variety of experiments that have been conducted to specifically test the effects of transgenic plants on soil microorganisms, and particularly examines the types of methods that are being used to study microbial interactions with transgenic plants.

No Evidence of an Impact on the Rhizosphere Diazotroph Community by the Expression of Bacillus thuringiensis Cry1Ab Toxin by Bt White Spruce

“…This study is the first to evaluate the impact of Bt white spruce, or any other Bt plant, on nitrogenfixing communities. No effect associated with the presence of the B. thuringiensis transgene was observed in this study, which is in agreement with other recent studies evaluating the impact on overall bacterial diversity (1,3,4,10,12,23,26,32). On the other hand, significant differences were found between diazotroph communities associated with white spruce in natural stands and those associated with trees in a plantation.…”

“…Particular attention was paid to studying the impact of Bt plants, which constitutively express the Cry1Ab insecticidal toxin of Bacillus thuringiensis, on rhizosphere microbial communities. Although studies demonstrating a negative impact of Bt crops on soil microbiota exist (7,44), more studies showing no effect have been published (1,3,4,10,12,23,26,32).…”

Assessment of biological and biochemical indicators in soil under transgenic Bt and non-Bt cotton crop in a sub-tropical environment

“…Any change in the quality of root exudates can modify the composition of the biota in soil (biodiversity), as well as their activity (Stotzky 2004;Patra et al 2006), and may produce deleterious or beneficial changes in the microbiota (Wei et al 2006;Griffiths et al 2006). To date, there has been limited research to investigate the influence of Bt-crops and Bt-toxins on soil processes (see Bruinsma et al 2003;Dunsfield and Germida 2004;Stotzky 2004;O'Callaghan et al 2005;Liu et al 2005;Fang et al 2007). …”

Impact of transgenic cottons expressing cry1Ac on soil biological attributes

“…Most of the studies on impact of transgenic crops on soil properties carried out were restricted to contained or controlled conditions (Liu et al 2005). Although some research has examined the environmental impacts of the 'aboveground' portion of transgenic crops, relatively fewer research effort has focused on the effects of these crops on soil microbes (Bruinsma et al 2003) although no risk of growing transgenic Bt cotton on soil health is reported (Sun et al 2007, Sarkar et al 2009).…”