USDA-ARS, Wheat Health, Genetics and Quality Research Unit, Washington State University, Pullman, WA, 99164-6430, USA.
Department of Plant Pathology, Washington State University, Pullman, WA, 99164-6430, USA.
Microb Ecol. 2018 Jul;76(1):240-257. doi: 10.1007/s00248-017-1113-9. Epub 2017 Dec 7.
Glyphosate is the most-used herbicide worldwide and an essential tool for weed control in no-till cropping systems. However, concerns have been raised regarding the long-term effects of glyphosate on soil microbial communities. We examined the impact of repeated glyphosate application on bulk and rhizosphere soil fungal communities of wheat grown in four soils representative of the dryland wheat production region of Eastern Washington, USA. Further, using soils from paired fields, we contrasted the response of fungal communities that had a long history of glyphosate exposure and those that had no known exposure. Soil fungal communities were characterized after three cycles of wheat growth in the greenhouse followed by termination with glyphosate or manual clipping of plants. We found that cropping system, location, year, and root proximity were the primary drivers of fungal community compositions, and that glyphosate had only small impacts on fungal community composition or diversity. However, the taxa that responded to glyphosate applications differed between rhizosphere and bulk soil and between cropping systems. Further, a greater number of fungal OTUs responded to glyphosate in soils with a long history of glyphosate use. Finally, fungal co-occurrence patterns, but not co-occurrence network characteristics, differed substantially between glyphosate-treated and non-treated communities. Results suggest that most fungi influenced by glyphosate are saprophytes that likely feed on dying roots.
草甘膦是全球使用最广泛的除草剂，也是免耕种植系统杂草控制的重要工具。然而，人们对草甘膦对土壤微生物群落的长期影响表示担忧。我们研究了重复施用草甘膦对美国华盛顿东部旱地小麦种植区四种土壤中小麦根际和非根际土壤真菌群落的影响。此外，我们使用来自配对田地的土壤，对比了长期接触草甘膦和无已知接触的真菌群落的反应。在温室中进行了三轮小麦生长后，用草甘膦终止或手动剪除植物，对土壤真菌群落进行了特征描述。我们发现，种植制度、地点、年份和根系接近度是真菌群落组成的主要驱动因素，草甘膦对真菌群落组成或多样性只有很小的影响。然而，根际和非根际土壤以及种植系统之间，对草甘膦处理的反应不同。此外，在长期使用草甘膦的土壤中，更多的真菌 OTUs 对草甘膦有反应。最后，草甘膦处理和未处理群落之间的真菌共现模式差异很大，但共现网络特征没有差异。结果表明，受草甘膦影响的大多数真菌都是腐生菌，可能以死亡的根系为食。
