植物根系对粪肥施用土壤中抗生素抗性基因的选择性消除及机理研究

With the increasing use of antibiotics, the abundance and diversity of antibiotic resistance genes (ARGs) show a growing trend in the environment, which is a hidden danger to human health. Soil applied with livestock manure is one of the most serious ARGs pollution areas. Plant growth has a great influence on soil ARGs. We found that the abundance of some ARGs in soil was significantly reduced after planting, and even below detectable limit after continuous cropping. The mechanism behind this phenomenon is still unknown. In this project, soybean and rice continuous cropping will be carried out in the soil treated with manure. Variations of ARGs in soil, including rhizosphere soil and non-rhizosphere soil, before and after planting of each batch of plants will be detected by high-throughput PCR. The effects of root exudates on soil ARGs and related mechanisms will be studied by using a variety of omics techniques. Key components of root exudates will be identified and verified. Finally, the mechanism of plant selective remediation of ARGs in soil will be elucidated. An accurate understanding of the selection rules and mechanisms of soil ARGs by plants, especially in the practical environment of long-term application of manure, can provide a theoretical support for repairing ARGs pollution by using plants.

随着抗生素的大量使用，抗生素抗性基因 (Antibiotic resistance genes, ARGs) 在环境中的丰度和多样性不断增长，给人类健康带来隐患。常年施用禽畜粪便等农家肥的土壤是ARGs污染的重灾区。植物的生长对土壤ARGs有较大影响，申请人发现土壤中部分ARGs的丰度在植物种植后显著降低，且随植物种植代数的增加而降低至检测阈值下，其背后的机制仍然未知。本项目以多年施用粪肥的土壤为基质，在其中多代种植大豆或水稻，使用高通量PCR检测每代植物种植前后土壤中ARGs的变化(包括根际土和非根际土)，结合多种组学技术研究根系分泌物对土壤ARGs的影响规律和相关机理，找出关键的根系分泌物组分并进行验证。最终，阐明植物对土壤ARGs的选择性修复机制。该项目研究为植物修复ARGs污染，特别是在长期施用粪肥的土壤这一实际环境的ARGs修复提供理论支持。

了解抗生素耐药基因(Antibiotic resistance genes, ARGs)在植物根际的传播和出现，对于评估现代ARGs在土壤地球健康中的风险至关重要。然而，人们对植物根际的选择机制知之甚少。本项目首先分析了拟南芥根际微生物组三代富集过程中根际抗生素耐药基因组的动态变化，发现植物定向富集具有多种ARGs的有益功能细菌。利用宏基因组技术评估了四种常见作物(大麦、籼稻、粳稻和小麦)中耐药基因组的富集潜力，发现小麦根际含有更丰富的ARGs。最终对小麦根际微生物组进行了三代连续培育，发现约60%的ARGs与小麦根际富集的有益细菌有关，这些细菌可能进入土壤食物网并对人类健康产生潜在风险，尽管它们在植物根际也发挥着有益的功能。本项目取得的研究成果为ARGs在植物根际的传播提供了新的见解，所获得的数据可能有利于农业可持续发展和生态安全。