Spatial soil heterogeneity has a greater effect on symbiotic arbuscular mycorrhizal fungal communities and plant growth than genetic modification with Bacillus thuringiensis toxin genes |
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Authors: | Tanya E. Cheeke Ursel M. Schütte Chris M. Hemmerich Mitchell B. Cruzan Todd N. Rosenstiel James D. Bever |
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Affiliation: | 1. Department of Biology, Portland State University, Portland, OR, USA;2. Department of Biology, Indiana University, Bloomington, IN, USA;3. Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden;4. Integrated Program in the Environment, Indiana University, Bloomington, IN, USA;5. Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA |
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Abstract: | Maize, genetically modified with the insect toxin genes of Bacillus thuringiensis (Bt), is widely cultivated, yet its impacts on soil organisms are poorly understood. Arbuscular mycorrhizal fungi (AMF) form symbiotic associations with plant roots and may be uniquely sensitive to genetic changes within a plant host. In this field study, the effects of nine different lines of Bt maize and their corresponding non‐Bt parental isolines were evaluated on AMF colonization and community diversity in plant roots. Plants were harvested 60 days after sowing, and data were collected on plant growth and per cent AMF colonization of roots. AMF community composition in roots was assessed using 454 pyrosequencing of the 28S rRNA genes, and spatial variation in mycorrhizal communities within replicated experimental field plots was examined. Growth responses, per cent AMF colonization of roots and AMF community diversity in roots did not differ between Bt and non‐Bt maize, but root and shoot biomass and per cent colonization by arbuscules varied by maize cultivar. Plot identity had the most significant effect on plant growth, AMF colonization and AMF community composition in roots, indicating spatial heterogeneity in the field. Mycorrhizal fungal communities in maize roots were autocorrelated within approximately 1 m, but at greater distances, AMF community composition of roots differed between plants. Our findings indicate that spatial variation and heterogeneity in the field has a greater effect on the structure of AMF communities than host plant cultivar or modification by Bt toxin genes. |
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Keywords: | 454 pyrosequencing arbuscular mycorrhizal fungi
Bacillus thuringiensis
Bt maize genetically modified spatial variation |
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