灰杨根尖不同区段吸收NH4+(NO3-)差异的生理与miRNAs调控机制

根尖是植物吸收氮素(N)的主要器官，但根尖不同区段对于铵态氮(NH4+)/硝态氮(NO3-)的吸收具有差异，其生理和microRNAs(miRNAs)调控机制仍不清楚。本项目拟以灰杨(Populus × canescens)为试材，利用离子选择性微电极技术(SIET)，分析灰杨根尖不同区段对NH4+(NO3-)吸收速率的差异，同时分析氮素吸收同化相关酶活性，揭示生理生化调节规律。在此基础上，利用miRNAs高通量测序技术鉴定根尖不同区段差异表达的miRNAs，并结合降解组测序、数字基因表达谱以及生物信息学等方法，分析miRNAs靶基因的差异表达模式，阐明miRNAs及其靶基因的表达调控机制。最后，综合阐明灰杨根尖不同区段吸收氮素差异的生理与miRNAs调控机制。研究成果既可为培育氮素吸收利用效率高的林木奠定理论基础，也可为人工林的氮肥管理提供科学依据，具有理论与实践意义。

The root is the major organ of the plant for nitrogen acquisition. Different root zones have distinct capacities for uptake of NH4+(NO3-), but the underlying physiological and microRNAs (miRNAs) regulation mechanisms remain unknown. In this study, we will measure the influxes of NH4+(NO3-) in different root zones of Populus×canescens to select roots sections with maximum and minimum influxes of nitrogen ions using the scanning ion-selective electrode technique (SIET). We will also analyze the concentrations of NH4+(NO3-) and activities of enzymes involved in NH4+(NO3-) assimilation in selected root zones with contrast capacities for uptake of nitrogen ions. Furthermore, the miRNAs expression patterns will be analyzed in selected root zones of poplars using RNA-sequencing technology. Based on the identified miRNAs, the target genes and their expression patterns of miRNAs will be analyzed in selected root zones of poplars by sequencing degradome and RNAs. Finally, we will integrate the influxes of nitrogen ions, biochemical and miRNAs date to elucidate the physiological and miRNAs regulation mechanisms underlying the differences in influxes of NH4+(NO3-) in distinct root zones of poplars. The output of this study will provide theoretic basis for breeding woody plants with high nitrogen use efficiency, and also give experimental evidence for nitrogen management in forest plantations.