Six transgenic events (TEv) of Castanea dentata, each containing four to five transgenes with varying insertion numbers, were field-tested for non-target impacts on root symbiotic ectomycorrhizal fungi (EMF). Also included was the cloned plant used to create the TEv as a control, and a variety of seed-grown C. dentata and other Castanea species or hybrids to test natural variation and the effect of micropropagation procedures. The field sites included two open-field and two shelterwood sites. Two of the six TEv, both containing the transgene encoding the antimicrobial peptide ESF39, formed significantly less ectomycorrhizas than the control in their first season in the field; no differences were detected in the next season. No other differences in receptivity to EMF or between EMF communities were detected among the various experimental plants. No significant impacts on EMF of the transgenes encoding oxalate oxidase, GFP, BAR and NPTII were detected. Nor were impacts due to differences in insert copy number, insert position or micropropagation procedures. The shelterwood sites had significantly higher colonization than both of the open-field sites. Both open sites had relatively low diversity and communities composed of EMF typically found in pioneer communities. One of the shelterwood sites had significantly higher diversity and EMF typical of mature forest communities. The other did not; possible reasons for this are discussed. This study compared experimental plants with high numbers of gene inserts, differences found did not correlate with the number of insertion events or genes used, indicating that pleiotropic effects are rare in this species. Differences in colonization were temporally dependent which should be considered in future studies. Site characteristics affected both colonization by and community composition of EMF.
|Advisor:||Horton, Thomas R., Tao, Wendong|
|Commitee:||Maynard, Charles A., Powell, William A.|
|School:||State University of New York College of Environmental Science and Forestry|
|Department:||Environmental and Forest Biology|
|School Location:||United States -- New York|
|Source:||MAI 52/01M(E), Masters Abstracts International|
|Subjects:||Ecology, Microbiology, Forestry|
|Keywords:||Castanea dentata, Ectomycorrhizal fungi, Ectomycorrhizal fungus communities, Genetically modified organisms, Mycorrhizal networks, Non-target impacts|
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