酚类化合物在植物抗病、抗逆过程中发挥着重要作用，酚类衍生物木质素还是造纸和利用生物质生产酒精的主要屏障。我们前期的研究表明，miR1444a很可能介导多酚氧化酶参与调控毛果杨酚类化合物和木质素的产生。为了验证这一假设，本项目将以基因组全序列测定已完成的毛果杨为试材，构建miR1444a过表达载体，遗传转化，获得miR1444a过表达的转基因毛果杨；比较分析转基因和非转基因植物体中酚类化合物和木质素的组分和含量变化，结合转录组和降解组的高通量分析，找出miR1444a表达量、基因表达量、酚类化合物的组成与含量、木质素的组成与含量之间的关系；从全基因组水平构建miR1444a调控的基因网络，验证miR1444a介导多酚氧化酶调控酚类化合物和木质素产生的假设，阐明其分子机制，为彻底揭示毛果杨酚类化合物和木质素产生的遗传调控机制和利用基因工程手段调控酚类化合物和木质素的产生奠定基础。

Phenolic compounds play significant roles in plant response to biotic and abiotic stresses. Lignin, a phenolic derivative, is the main barrier in paper pulping and bioethanol production. Based on our previous results, it is very likely that miR1444a regulates the production of phenolic compounds and lignin in Populus trichocarpa through targeting polyphenol oxidase genes for cleavage. With the aim to test this hypothesis, we propose to use P. trhichocarpa, which has the whole genome sequence available, as experimental materials. We will construct miR1444a overexpression vector and then introduce it into P. trichocarpa. The content and composition of phenolic compounds and lignin will be comparatively analyzed in transgenics and non-transgenics. High-throughput degradome sequencing and RNA-seq will be performed for transcriptome-wide analysis of genes directly cleaved or indirectly regulated by miR1444a. All of the data obtained will be further comprehensively analyzed for elucidating the relationships among miR1444a expression level, protein-coding gene expression level, the content and composition of phenolic compounds, and the content and composition of lignin in P. trichocarpa. We expect that the regulatory network of miR1444a will be constructed at the whole genome level and the regulatory mechanism of miR1444a on the production of phenolic compounds and lignin will be finally elucidated. The results will provide useful information for elucidating the genetic regulatory mechanism of phenolic compounds and lignin production and will serve as a basis for controlling phenolic compounds and lignin production through genetic engineering approaches.