Effect of Cotton Plant Genetically Modified with An Antimicrobial Synthetic Peptide D4E1 On Soil Microbial Diversity and Enzyme Activity.

One of the least understood areas in the environmental risk assessment of genetically modified crops is their impact on soil- and plant- associated communities.  Incorporation of transgenic plant products into the soil could alter the soil microbial diversity due to responses by microorganisms to novel proteins (Dunfield et al. 2004).  Genetic modification has been used to confer disease resistance to the two fungal pathogens associated with Cotton Seedling Disease, in Alabama, (Rhizoctonia Solani and Pythium), a antimicrobial synthetic peptide D4E1, which has been shown in vitro and in planta to have broad spectrum antimicrobial action against many fungal orders, has been transformed into cotton seeds (Rajasekaran et al. 2005).   In a completely randomized designed field trial, two 150 x150 ft test plots were assigned either one of 3 isogenic lines of cotton seed transformed with D4E1  (designated 357, 358, and 373) or a control line containing GUS marker gene.  The soil was then randomly sampled and composited and denaturant gradient gel electrophoresis (DGGE) was conducted in order to discern if the introduction of a synthetic antimicrobial peptide would have any effect on the soil microbial communities present in the three isogenic lines and the control.   Phosphatase enzyme assays were also performed in order to determine if the enzymatic activity was affected, in any way, by the introduction of the genetically modified crop.One of the least understood areas in the environmental risk assessment of genetically modified crops is their impact on soil- and plant- associated communities.  Incorporation of transgenic plant products into the soil could alter the soil microbial diversity due to responses by microorganisms to novel proteins (Dunfield et al. 2004).  Genetic modification has been used to confer disease resistance to the two fungal pathogens associated with Cotton Seedling Disease, in Alabama, (Rhizoctonia Solani and Pythium), a antimicrobial synthetic peptide D4E1, which has been shown in vitro and in planta to have broad spectrum antimicrobial action against many fungal orders, has been transformed into cotton seeds (Rajasekaran et al. 2005).   In a completely randomized designed field trial, two 150 x150 ft test plots were assigned either one of 3 isogenic lines of cotton seed transformed with D4E1  (designated 357, 358, and 373) or a control line containing GUS marker gene.  The soil was then randomly sampled and composited and denaturant gradient gel electrophoresis (DGGE) was conducted in order to discern if the introduction of a synthetic antimicrobial peptide would have any effect on the soil microbial communities present in the three isogenic lines and the control.   Phosphatase enzyme assays were also performed in order to determine if the enzymatic activity was affected, in any way, by the introduction of the genetically modified crop.