Newman Molli M, Lorenz Nicola, Hoilett Nigel, Lee Nathan R, Dick Richard P, Liles Mark R, Ramsier Cliff, Kloepper Joseph W
Department of Entomology and Plant Pathology, Auburn University, CASIC Building, Auburn, AL 36849, USA.
School of Environment and Natural Resources, The Ohio State University, 2021 Coffey Road, Columbus, OH 43210, USA.
Sci Total Environ. 2016 May 15;553:32-41. doi: 10.1016/j.scitotenv.2016.02.078. Epub 2016 Feb 21.
In commercial agriculture, populations and interactions of rhizosphere microflora are potentially affected by the use of specific agrichemicals, possibly by affecting gene expression in these organisms. To investigate this, we examined changes in bacterial gene expression within the rhizosphere of glyphosate-tolerant corn (Zea mays) and soybean (Glycine max) in response to long-term glyphosate (PowerMAX™, Monsanto Company, MO, USA) treatment. A long-term glyphosate application study was carried out using rhizoboxes under greenhouse conditions with soil previously having no history of glyphosate exposure. Rhizosphere soil was collected from the rhizoboxes after four growing periods. Soil microbial community composition was analyzed using microbial phospholipid fatty acid (PLFA) analysis. Total RNA was extracted from rhizosphere soil, and samples were analyzed using RNA-Seq analysis. A total of 20-28 million bacterial sequences were obtained for each sample. Transcript abundance was compared between control and glyphosate-treated samples using edgeR. Overall rhizosphere bacterial metatranscriptomes were dominated by transcripts related to RNA and carbohydrate metabolism. We identified 67 differentially expressed bacterial transcripts from the rhizosphere. Transcripts downregulated following glyphosate treatment involved carbohydrate and amino acid metabolism, and upregulated transcripts involved protein metabolism and respiration. Additionally, bacterial transcripts involving nutrients, including iron, nitrogen, phosphorus, and potassium, were also affected by long-term glyphosate application. Overall, most bacterial and all fungal PLFA biomarkers decreased after glyphosate treatment compared to the control. These results demonstrate that long-term glyphosate use can affect rhizosphere bacterial activities and potentially shift bacterial community composition favoring more glyphosate-tolerant bacteria.
在商业农业中，根际微生物区系的种群和相互作用可能会受到特定农用化学品的影响，可能是通过影响这些生物体中的基因表达。为了对此进行研究，我们检测了耐草甘膦玉米（Zea mays）和大豆（Glycine max）根际内细菌基因表达的变化，以响应长期草甘膦（PowerMAX™，美国孟山都公司，密苏里州）处理。在温室条件下，使用根箱进行了一项长期草甘膦施用研究，所用土壤之前没有草甘膦接触史。在四个生长周期后，从根箱中收集根际土壤。使用微生物磷脂脂肪酸（PLFA）分析来分析土壤微生物群落组成。从根际土壤中提取总RNA，并使用RNA测序分析对样品进行分析。每个样品共获得2000 - 2800万个细菌序列。使用edgeR比较对照样品和草甘膦处理样品之间的转录本丰度。总体而言，根际细菌元转录组以与RNA和碳水化合物代谢相关的转录本为主。我们从根际中鉴定出67个差异表达的细菌转录本。草甘膦处理后下调的转录本涉及碳水化合物和氨基酸代谢，而上调的转录本涉及蛋白质代谢和呼吸作用。此外，涉及铁、氮、磷和钾等养分的细菌转录本也受到长期草甘膦施用的影响。总体而言，与对照相比，草甘膦处理后大多数细菌和所有真菌PLFA生物标志物均减少。这些结果表明，长期使用草甘膦会影响根际细菌活性，并可能使细菌群落组成发生变化，有利于更多耐草甘膦细菌。
