浮萍根系分泌物芥酸酰胺的释放留存特征及影响反硝化的作用机理研究

反硝化是农田氮素损失的重要途径。影响氮素反硝化过程的植物－微生物互作机制是植物营养领域的研究热点。植物可通过根系分泌物来促进微生物的反硝化活性，然而对其释放留存特征和作用机理缺乏深入研究。本项目以农田中广泛存在的浮萍和反硝化细菌Pseudomonas fluorescens为研究对象，综合运用气相色谱、色谱－质谱联用技术和根际互作研究方法，以浮萍根系分泌物脱氮促进物质芥酸酰胺为切入点，研究其在根际环境中的释放规律及不同环境因子的影响，考察芥酸酰胺的积累规律和自身降解情况，以揭示其在浮萍根际环境中的释放留存特征；探讨芥酸酰胺对P. fluorescens脱氮途径、反硝化产物和反硝化还原酶活性的影响以及NO3-、O2 对反硝化促进过程的影响，以期阐明芥酸酰胺促进反硝化脱氮的作用机理。研究成果可为浮萍－微生物根际互作体系调控农田生态系统氮素反硝化损失和净化富营养水体氮提供科学依据和应用基础。

Denitrification is an important pathway for agricultural nitrogen loss. The plant-microbe interaction mechanism responsible for affecting nitrogen transformation and utilization is a hot topic in the field of plant nutrition. Plant can stimulate the denitrification activity of microorganisms through root exudates. However, there is a lack of intensive study of its mechanism, and release and accumulation characteristics. With the application of gas chromatography, gas chromatography-mass spectrometry techniques and rhizosphere interactions methods, this project focuses on the plant duckweed widely distributed in agricultural area and the denitrifying bacterium Pseudomonas fluorescens. Based on the N-removal stimulants in duckweed root exudates erucamide, the exudation characteristic of erucamide, the effect of different factors, and the accumulation and biodegradation of erucamide were also investigated to clarify the release and accumulation characteristics of erucamide and the key regulation factor. The effect of erucamide on nitrogen removal pathway, denitrification products, denitrification reductase activity, and factors (NO3- and O2) involved in the stimulation was discussed to reveal the mechanism underlying duckweed root exudate erucamide on bacterial nitrogen removal. This study can provide the scientific basis and applied value for effectively regulating nitrogen loss by denitrification in agro-ecosystems and purifying nitrogen from eutrophic water body by duckweed-microorganism interactions in the rhizosphere.