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United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Strategies for Improved Water Quality and Ecosystem Integrity within Agricultural Watersheds

Location: Water Quality and Ecology Research

Title: Impact of seven years of glyphosate resistant corn and glyphosate applications under conventional and reduced tillage on bulk and rhizosphere soil exoenzyme activities and corn root endophytic microbial community structure)

Author
item Jenkins, Michael
item Locke, Martin
item Reddy, Krishna
item Mittelberg, Tara
item Mcchesney, Daniel - Dan
item Steinriede, Robert - Wade

Submitted to: American Society for Microbiology General Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/5/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: Abstract only

Technical Abstract: Background: Conservation tillage practices across the country have been implementing genetically engineered glyphosate resistant corn crops along with applications of the herbicide glyphosate. We tested the hypothesis that seven years of glyphosate applications to both glyphosate resistant and non-resistant corn under reduced and conventional tillage would impact key soil exoenzymes involved in initial breakdown of organic matter and their associated root endophytic microbial communities. Method: The experimental design was a randomized complete block with glyphosate resistant (GR) and non-GR corn, with and without glyphosate applications under reduced and conventional tillage. Bulk and rhizosphere soil samples were analyzed for four exoenzymes , ß-glucosidase (BG), ß-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), acid phosphatase (AP), and for fluorescein diacetate (FDA) hydrolysis as a measure of total microbial activity. DNA was extracted from surface sterilized corn roots and 16sRNA genes from bacterial and archaeal components of the root endophytic microbial communities were sequenced with Illumina‚Äôs MiSeq platform and with Roche 454 FLX sequencer machine, respectively. Sequences were analyzed with mothur. Results: Except for FDA and LAP, differences (at P < 0.05) in mean BG, AP, and NAG, activities, as well as C:P and C:N acquisition ratios were observed for both rhizosphere and bulk soil samples, and tillage practice. Preliminary sequence analyses indicate significant differences in root endophytic bacterial and archaeal community structures between experimental treatments. Conclusions: Interactions between treatments appeared to impact exoenzyme activities and acquisition ratios. Preliminary analyses of 16sRNA genes from archaeal and bacterial root endophytic communities indicated significant differences between treatments.

Last Modified: 8/24/2016
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