氮素是调控林木木材形成的主要环境因子，改变细胞壁多糖和木质素含量。申请人前期研究表明，水解细胞内/外核苷磷酸的关键酶APY1/2主要在维管组织表达，参与氮素调控木材纤维细胞壁的形成，但具体的作用机制尚不清楚。本项目以84K杨（Pg）为研究对象，在前期研究基础上，分析PgAPY1/2的组织和细胞定位；创制杨树过表达和基因敲除株系，鉴定PgAPY1/2的酶学特性；利用免疫荧光、高效阴离子交换色谱、qRT-PCR等技术分析氮素盈亏条件下各株系木材纤维细胞壁的组成、高尔基体核苷糖转运、细胞外ATP含量以及胞外ATP信号途径下游基因PER52等的转录表达模式，明确PgAPY1/2参与氮素调控细胞壁形成的生理途径，综合阐明PgAPY1/2在氮素调控木材纤维细胞壁形成中的作用机制。研究结果可为利用氮素提高木材产量与品质提供科学依据。

Nitrogen supply affects wood production and quality, as well as the content of cell wall polysaccharides and lignin. APYs are key enzymes for hydrolyzing intra-/extracellular nucleoside phosphates. APYs mediate the regulation of the formation of wood cell wall by nitrogen, but the specific mechanisms are still unclear. In this study, we will clone PgAPY1/2 genes from Populus alba×Populus glandulosa for functional analysis. Tag fusion expression vectors will be constructed to investigate the tissue and subcellular localization. To identify molecular functions of the PgAPY1/2 genes, we will analyze the enzymatic characteristics and nucleoside sugar transport using PgAPY1/2 overexpression and genomic-editing poplars. To elucidate the physiological pathway of nitrogen-regulated cell wall formation mediated by PgAPY1/2, we will analyze the chemical composition of the wood cell wall, the content of cell wall polysaccharides, the level of extracellular ATP, and the expression levels of eATP downstream genes, using Fourier infrared spectroscopy, immunofluorescence, qRT-PCR, respectively. Finally, we will elucidate physiological and molecular mechanisms underlying PgAPY1/2-mediated nitrogen regulation of cell wall formation in poplars. The output of this study will provide theoretic basis for the use of nitrogen to increase wood production and quality.