氮转化菌群结构对草地瑞香狼毒种群爆发的响应

Nitrogen is one of limited factors for plant growth in arid and semi-arid areas. Changes in nitrogen cycling and nitrogen availability are important responses to plant invasion, while soil microorganisms play dominant roles in transformation and utilization of nitrogen. The burst of Stellera chamaejasme L., a toxic weed, increased nitrogen availability and turnover rate, however, the biological mechanism is not well understood. In this project, S. chamaejasme L. will be selected as a subject. The genes encoding the key enzymes involved in main reactions of nitrogen transformation are used as markers to explore the diversities of nitrogen-cycling microorganisms. Clone library, fluorescence quantitative PCR, analysis of the process of nitrogen transformation and soil physical and chemical properties were used to study the influence of the burst of S. chamaejasme L. on the structures of nitrogen-cycling microflora and the relation between the burst of S. chamaejasme L., the structures of nitrogen-cycling microflora, nitrogen-transforming function and soil properties. The aims of this study are to determine the diversities of nitrogen-cycling microorganisms under the burst of S. chamaejasme L. and elucidate the responses of the structure of microflora. The results submitted by this project will help to understand the mechanism of the influence of key species on nitrogen cycling and the driver factors of the burst of S. chamaejasme L., and will provide some scientific fundamentals for ecological restoration of degraded grasslands, development of soil quality, and prediction and prevention for burst of toxic weed.

氮是干旱和半干旱地区植物生长主要的限制因子之一。氮循环及氮有效性变化是土壤对植物入侵的重要响应，而土壤微生物在氮转化及其利用方面发挥主导性作用。有毒杂草瑞香狼毒种群爆发提高草地氮有效性和氮转化率，但引起这两者变化的生物学机制尚缺乏研究。本项目以瑞香狼毒为对象，以编码土壤氮转化主要过程的关键酶基因为标记，采用克隆文库和荧光定量PCR技术，并测定分析氮转化作用和土壤物理化学性质，研究瑞香狼毒种群爆发对草地固氮、硝化和反硝化作用菌群结构的影响以及瑞香狼毒种群爆发、土壤氮转化微生物群落结构、氮转化功能和土壤特征之间的关系，全面掌握瑞香狼毒种群爆发背景下草地氮转化相关微生物多样性，阐明微生物群落结构对草地退化的响应规律，可深入理解关键种对草地氮循环的影响机制和退化草地瑞香狼毒种群爆发的驱动因素，为退化草地的生态恢复、预测有毒杂草种群爆发和土壤质量的发展趋势以及预防有毒杂草种群爆发提供理论依据。