草甘膦除草剂中佐剂对大豆根际土壤微生物群落的影响及其机制研究

The commercial planting of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) transgenic glyphosate-resistant soybeans with large area has brought significant economic and social benefits. However, many studies have shown that with the dramatic increase in the dosage of glyphosate herbicide, the larger amount of adjuvants of glyphosate would produce certain ecological risks to the soil environment, especially to the rhizosphere soil and its microbial community which acting as the main link between soil and environment. Therefore, it is of great scientific significance to analyze the effects of adjuvants on the rhizosphere soil microbial community and soil ecological environment. In this project, by using the EPSPS transgenic glyphosate-resistant soybean as material, and by analyzing the high-throughput sequencing of rhizosphere microbial metagenome and metatranscriptome, GEOCHIP and soil quality index, we intends to deeply clarify the effects of POEA, one kind of glyphosate herbicide adjuvant widely applied, on the rhizosphere microbial community and its possible mechanism. In addition, urea phosphate (UPP), one kind of new good environment adjuvant, will be used as control. The implementation of this project would not only reveal the possible risk and its theoretical mechanism of glyphosate adjuvant on soil microbial community, but also provide references for the selection and application of efficient adjuvants with low toxicity, environmental management, risk control, as well as the conservation and sustainable utilization of soil ecological resources.

尽管转EPSPS基因抗草甘膦大豆的商业化大面积种植带来了显著的经济社会效益，但不少研究显示，伴随着草甘膦除草剂用量的剧增，其制剂中的大量佐剂可能对土壤环境存在一定的生态风险，尤其是对于衔接土壤环境与植物间交互作用的主要纽带——根际土壤及其微生物群落。因此，探讨草甘膦佐剂对大豆根际土壤微生物群落及土壤生态环境的影响无疑具有重要意义。本项目拟以转EPSPS基因抗草甘膦大豆等为试材，采用宏基因组、宏转录组等高通量测序、GEOCHIP土壤微生物功能基因芯片及土壤质量指标分析，深入研究已广泛应用的草甘膦制剂中的佐剂成分POEA对转EPSPS基因抗草甘膦大豆根际土壤微生物群落的影响及其可能机理（同时以另一新型环境良好佐剂UPP为参照）。项目实施不仅可揭示主要的草甘膦农药佐剂对土壤微生物的可能风险及理论机制，也可为低毒高效农药佐剂的选择应用与环境风险管控提供参考，为土壤生态保护及可持续利用作出贡献。

抗草甘膦转基因作物作为最具代表性的转基因作物，可产生显著的经济社会效益，但伴随除草剂大量使用，草甘膦及其佐剂对作物矿质营养、病害以及土壤微生物影响的生态风险日益引人关注，因此有必要深入研究草甘膦尤其是其佐剂影响土壤微生物群落的潜在在风险及其可能的机制。本项目主要以抗草甘膦转基因大豆品系为作物种植材料，采用人为可控环境条件的根际箱实验与实际大田试验相结合的方式，借助于16S rRNA、ITS可变区、宏基因组高通量测序、GeoChip功能基因芯片等多种分析技术，通过分析植物形态与生理生化性状、土壤理化性质与肥力相关指标，深入研究了除草剂草甘膦及其常用佐剂（POEA）、新型环境友好佐剂（UPP）对土壤环境微生物群落结构组成、功能基因表达的影响及其机理，并与土壤质量、肥力以及由此而引起的作物生长状况变化相关联。主要研究结果表明，与单独施加草甘膦相比，草甘膦和常规剂量佐剂POEA或UPP的联用对抗草甘膦转基因大豆根际土壤细菌、真菌群落的α以及β多样性总体上没有产生显著影响；但在物种分类学水平上均可显著富集一些植物促生根际细菌、溶磷真菌以及病原微生物，且这些物种的丰度变化一定程度上与佐剂剂量依赖效应有关；值得注意的是，部分因佐剂施用而富集的物种在对应的佐剂高剂量施用时反而发生了去富集作用，回到了与单独施加草甘膦时相近的丰度水平。进一步分析发现，相比于草甘膦单独施用，常规剂量的佐剂POEA与草甘膦联用可显著降低转基因大豆根际土中大量与C、N、P营养元素循环相关的功能基因丰度，而UPP则无此种影响。此外，尽管转基因大豆根际微生物群落因草甘膦佐剂的施用存在上述多种影响，大豆植株性状及其根际土的理化性质并未因佐剂施用发生显著变化。目前已发表标注资助号（31870495）的SCI论文10篇，申请国家发明专利1项。培养4名博士生和7名硕士生。