Department of Entomology, China Agricultural University, Beijing 100193, China.
Department of Entomology, China Agricultural University, Beijing 100193, China.
Ecotoxicol Environ Saf. 2022 May 1;236:113452. doi: 10.1016/j.ecoenv.2022.113452. Epub 2022 Mar 30.
Bt cotton successfully controlled major devastating pests in cotton，such as Helicoverpa armigera and Spodoptera exigua, and led to a drastic decrease in insecticide use in cotton fields, and it has been grown commercially worldwide. However, Bt cotton cultivation left Bt toxin residues in the soil, resulting in a response by its microbiome that caused potential environmental risks. In this research, the metagenomics analysis was performed to investigate the structure and functions of the soil bacterial community in the Bt cotton field from the Binzhou, Shandong province of China, where the Bt cotton has been cultivated for over fifteen years. Analysis of the function genes proved that the receptors of Bt toxins were absent in the soil bacteria and Bt toxins failed to target the soil bacteria. The microbiome structure and function were highly influenced by Bt cotton cultivation, however, no significant change in the total abundance of the bacteria was observed. Proteobacteria was the largest taxonomic group in the soil bacterial (42-52%) and its abundance was significantly increased after Bt cotton cultivation. The increase of Proteobacteria abundance resulted in an increase in ABC transporters gene abundance, indicating the improved ability of detoxification metabolism over Bt cotton cultivation. Xanthomonadales could be a biomarker of the Bt cotton group, whose abundance was significantly increased to contribute to the increase of the genes abundance in ABC transporters. The abundance of apoptosis genes was significantly decreased, and it might be related to the increase of Proteobacteria abundance by Bt cotton cultivation. In addition, Myxococcales was responsible for carotenoid biosynthesis, whoes genes abundance was significantly decreased due to the decrease of Myxococcales abundance by Bt cotton cultivation. These changes in soil bacterial community structure and functions indicate the influence by Bt cotton cultivation, leading to an understanding of the bacteria colonization patterns due to successive years of Bt cotton cultivation. These research results should be significant for the rational risk assessment of Bt cotton cultivation.
转Bt 基因棉花成功控制了棉花上的主要毁灭性害虫，如棉铃虫和斜纹夜蛾，导致棉花田杀虫剂用量大幅减少，已在全球范围内商业化种植。然而，Bt 棉花种植在土壤中留下了 Bt 毒素残留，导致其微生物组产生反应，从而带来潜在的环境风险。在这项研究中，对来自中国山东省滨州市的 Bt 棉花种植田的土壤细菌群落结构和功能进行了宏基因组分析，该地区已经种植 Bt 棉花超过十五年。功能基因分析证明，Bt 毒素的受体不存在于土壤细菌中，Bt 毒素也不能靶向土壤细菌。Bt 棉花种植对微生物组的结构和功能有很大影响，但细菌的总丰度没有明显变化。变形菌门是土壤细菌中最大的分类群（42-52%），在 Bt 棉花种植后其丰度显著增加。变形菌门丰度的增加导致 ABC 转运蛋白基因丰度的增加，表明 Bt 棉花种植后解毒代谢能力提高。黄单胞菌目可能是 Bt 棉花组的生物标志物，其丰度显著增加，导致 ABC 转运蛋白基因丰度增加。凋亡基因的丰度显著下降，这可能与 Bt 棉花种植导致变形菌门丰度增加有关。此外，粘球菌目负责类胡萝卜素生物合成，由于 Bt 棉花种植导致粘球菌目丰度下降，其基因丰度显著下降。这些土壤细菌群落结构和功能的变化表明了 Bt 棉花种植的影响，了解了由于连续多年种植 Bt 棉花导致的细菌定殖模式。这些研究结果对于 Bt 棉花种植的合理风险评估具有重要意义。
