Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture, Beijing, 100081, PR China.
Department of Microbiology, Cornell University, Ithaca NY, 14853, USA.
Environ Pollut. 2019 Oct;253:302-311. doi: 10.1016/j.envpol.2019.07.018. Epub 2019 Jul 9.
Fomesafen, a long-lived protoporphyrinogen-oxidase inhibitor, specially developed for post-emergence control of broad-leaf weeds, is used widely in soybean fields in northern China (Dayan and Duke, 2010). The impact of fomesafen on microbial communities in rhizosphere soils, however, is unknown. In this study we examined fomesafen degradation as well as its effects in the rhizosphere of soybean plants grown in a greenhouse. Fomesafen had shorter half-life in rhizosphere soil than previously reported for bulk soil from the same location (87 vs 120 days). The enzyme activity of soil extracts and the microbial community composition of 16S rRNA genes (16S) amplified from soil DNA were also investigated. Although not immediately apparent, both the high (37.5 mg kg) and low (18.75 mg kg) doses of fomesafen significantly decreased urease and invertase activities in the rhizosphere soil from days 30 and 45 respectively until the end of the experiment (90 days). Analysis of 16S amplicons demonstrated that fomesafen had a dose dependent effect, decreasing alpha diversity and altering beta diversity. Significant phylum level decreases were observed in five of the ten phyla that were most abundant in the control. Proteobacteria was the only phylum whose relative abundance increased in the presence of fomesafen, driven by increases in the genera Methylophilacaea, Dyella, and Sphingomonas. The functional implications of changes in 16S abundance as predicted using PICRUSt suggested that fomesafen enriched for enzymes involved in xenobiotic metabolism and detoxification (cytochrome P450s and glutathione metabolism). Our data suggest that, despite being degraded more rapidly in the rhizosphere than in bulk soil, fomesafen had long-lasting functional impacts on the soil microbial community.
氟磺胺草醚是一种长寿命的原卟啉原氧化酶抑制剂，专门开发用于阔叶杂草的苗后防治，在中国北方的大豆田中广泛使用（Dayan 和 Duke，2010）。然而，氟磺胺草醚对根际土壤微生物群落的影响尚不清楚。在这项研究中，我们研究了氟磺胺草醚在温室中种植的大豆根际土壤中的降解及其作用。与同一地点的原状土壤相比，氟磺胺草醚在根际土壤中的半衰期更短（87 天比 120 天）。还研究了土壤提取物的酶活性和从土壤 DNA 扩增的 16S rRNA 基因（16S）的微生物群落组成。虽然不明显，但高（37.5 mg kg）和低（18.75 mg kg）剂量的氟磺胺草醚分别从第 30 天和第 45 天开始，一直到实验结束（90 天），显著降低了根际土壤中的脲酶和转化酶活性。16S 扩增子分析表明，氟磺胺草醚具有剂量依赖性效应，降低了 alpha 多样性并改变了 beta 多样性。在对照中最丰富的十个门中，有五个门观察到明显的门水平下降。在氟磺胺草醚存在的情况下，变形菌门是唯一相对丰度增加的门，这是由甲基噬氢菌属、Dyella 属和 Sphingomonas 属的增加驱动的。根据 PICRUSt 预测 16S 丰度的变化所暗示的功能意义表明，氟磺胺草醚富集了参与外来化合物代谢和解毒（细胞色素 P450 和谷胱甘肽代谢）的酶。我们的数据表明，尽管在根际土壤中的降解速度比在原状土壤中更快，但氟磺胺草醚对土壤微生物群落仍有持久的功能影响。
