根深叶茂，两者相辅相成。林木不定根发生的遗传调控机理迄今尚无明确的结论。杨树是林木分子生物学研究的模式树种，生根性状在杨树遗传改良中占有重要地位。本项目以miRNA及其靶基因互作为切入点，围绕生长素信号转导途径，开展杨树不定根发生的分子调控研究。首先，建立和完善杨树不定根发生的实验系统，阐明不定根形态建成，揭示根原基形成中特定组织或细胞对生长素信号的发根感受性；同时，利用降解组测序技术，检测和验证miR160、miR167、miR390、miR393及其ARF和TIR1/AFB家族靶基因，结合靶基因剪切位点同义突变，在杨树原生质体中定性和定量地分析它们之间的相互作用；最后，通过表达载体构建和杨树遗传转化，对转基因杨树进行系统地分子检测和表型分析，结合生根试验和不同激素诱导处理，解析上述miRNA与生长素信号互作对杨树不定根发生的调控作用，为改良杨树生根性状和种质创新提供理论依据。

Deep roots give rise to flourishing leaves, the two complement each other. However, up to now, genetic mechanisms underlying adventitious rooting for forest trees remain elusive. Poplar is accepted as a model system for molecular tree biology, and its rooting traits play an important role in the genetic improvement of poplars. Based on the interactions between miRNA and its target genes as a starting point, with the auxin signaling network as the focus, this project will study the molecular mechanism of poplar adventitious rooting. By establishing and improving the experimental system of poplar adventitious rooting, this study will investigate its morphogenesis and reveal auxin signal sensitivity of specific tissues or cell in root primordia. Meanwhile, miR160、miR167、miR390、miR393 and their target genes (ARF and TIR1/AFB) will be detected and validated by degradome sequencing technology, and the interactions between the above miRNAs and their target genes will be tested by PCR mutagenesis strategy and using transient expression assay in poplar protoplasts. Finally, we will systematically analyze their functions in adventitious rooting by expression vector construction and poplar genetic transformation experiments to explore the molecular regulatory networks of poplar adventitious rooting. This will provide a theoretical basis for the improvement of poplar rooting traits.