我国北方天然草原土壤编码有机磷矿化基因地理分布特征及成因

Phosphorus (P) is the main limiting factor of grassland productivity. Organic P mineralization plays an important role in plant P supply, and soil microorganisms are the key driving factors of organic P mineralization. However, the geographical distribution characteristics and environmental regulation mechanisms of key functional genes and microbial groups related to organic P mineralization are still not clear. In this project, we will collect the regional soil samples from natural grasslands in northern China, analyze geographical distribution patterns and mechanisms of soil organic P forms and their biological availability based on the organic P fractionation and 31P-NMR technology, elucidate the geographical distribution characteristics of organic P mineralization functional genes and their environmental driving factors combined with high-throughput sequencing, fluorescence quantitative PCR, bioinformatics and statistics, and illustrate the internal relationship between microbial functional groups and soil P components and their bioavailability. The effects of climate change on the mineralization of organic P and its microbiological mechanism will be clarified through long-term experiments of simulated rainfall and warming up. Moreover, we will also set up soil microcosm in laboratory to investigate the functional genes of organic P mineralization regulated by key environmental factors using metatranscriptomics analyses combined with omics technological analysis. Finally, we try to provide theoretical support and practical basis for sustainable development of grassland productivity.

磷是草原生产力的主要限制因子，有机磷矿化在其磷素供给中起着重要作用，而微生物是有机磷矿化的关键驱动因子，但有机磷矿化关键功能基因及微生物类群的地理分布特征及其环境因子调控机理尚不清楚。本项目拟以我国北方天然草原区域性土壤样品为研究对象，基于有机磷分级和31P-NMR技术，分析土壤有机磷形态及其生物有效性的地理分布特征与成因；应用高通量测序、荧光定量PCR，结合生物信息学和统计学等方法，阐明有机磷矿化功能基因地理分布特征及其环境环境驱动因子，解析微生物功能类群与土壤有磷组分及其生物有效性的内在联系。通过模拟降雨和升温长期定位试验，明确气候变化对有机磷矿化的影响及其微生物学机制，并设置关键环境因子调控室内培养试验，采用宏转录组结合多组学分析等方法揭示环境因子调控有机磷矿化过程的微生物学机制，为草原生产力可持续发展提供理论支撑和现实依据。

本研究以我国天然草原土壤为研究对象，调查了不同类型草原土壤有机磷（Po）组分及参与有机磷矿化的微生物地理分布特征及成因。研究结果表明，内蒙古温带草原土壤Po含量50-188 mg/kg，约占全磷（TP）含量的61.0%，主要以中稳性Po为主；西藏高寒草原土壤Po含量为123-597 mg/kg，占TP含量的23%-92%，以中活性Po和高稳性Po为主；31P-NMR检测的磷化合物均以正磷酸盐和磷酸单酯为主，但内蒙古温带草原土壤中没有检测到聚磷酸盐的存在。内蒙古不同类型草原土壤编码碱性磷酸酶（ALP）的phoD基因的优势菌属包括Amycolatopsis、Bacillus、Bradyrhizobium、Streptomyces和Pseudomonas，西藏高寒草原编码phoD基因的主要优势菌属为Bacillus、Streptomyces、Pseudomonas、Bradyrhizobium、Xanthomonas和Nostoc；土壤C/N/P比是内蒙古温带草原编码phoD基因的细菌群落结构的重要驱动因素，而土壤Olsen-P含量、C/N比和N/P比是西藏高寒草原土壤编码phoD基因细菌群落结构的主要驱动因素。短期降水量的改变均显著提高荒漠草原土壤柠檬酸浸提P（Citrate-P）的含量，但增加降水会降低土壤P o含量；，phoD基因群落Shannon多样性和Planctomycetes门的相对丰度则显著增加；降水量变化使细菌群落向高效同化养分的方向演变，其中Citrate-P和SMBN对群落的变化起到关键作用，而土壤P所起的作用大于土壤N，且存在N、P耦合效应。长期增温增水对显著降低土壤有效磷（Olsen-P）含量；；phoD基因群落主要受有机碳（SOC）和盐酸浸提磷（HCl-P）的影响，其β多样性差异主要是由增水而不是增温引起的。干湿交替显著影响荒漠草原土壤细菌群落结构，干燥过程显著降低了土壤细菌群落的功能多样性；而土壤经历再湿润后，细菌群落多样性快速显著增加，这直接影响土壤P养分循环；干湿交替条件下，荒漠草原土壤中Burkholderia、Komagataeibacter、Pseudomonas、Xanthomonas、Rhodopseudomonas等菌属在土壤P循环中起重要作用。本研究结果为天然草原生产力的可持续发展提供了理论依据。