叶脉是叶片营养物质的运输通道，直接影响叶片形态。解析叶脉发育的机制，对于叶片分子设计育种具有重要意义。PHD-finger4属于锌指蛋白基因，参与基因转录调控。本项目在前期构建的白桦叶片主脉三层基因调控网络中，发现抑制第一层PHD-finger4的表达会增加主脉的长度和直径。然而，PHD-finger4调控主脉发育的机制尚不清楚。针对该问题，本项目采用酵母双杂交和BiFC技术，研究PHD-finger4与第一层其他基因是否存在互作；以前期转基因株系为材料，采用ChIP和PCR技术，确定PHD-finger4与第二层基因的调控关系；克隆并转化第二层UTL1-1、AS2、YAB1基因，采用ChIP-seq技术，分析上述基因与第三层基因的调控关系。通过研究PHD-finger4与网络中各层基因的互作及调控关系，解析PHD-finger4调控叶片主脉发育的分子机制，为白桦叶片分子设计育种提供参考。

Leaf vein is the transport channel of leaf nutrients, which directly affects leaf morphology. It is of great significance for molecular design breeding of leaves to analyze the mechanism of vein development. PHD-finger4 is a zinc finger protein gene, which is involved in gene transcription regulation. In the early stage of our research, a three-layer gene regulatory network of the main vein of Betula pendula ‘Dalecartica’ was constructed, and the PHD-finger4 was in the first layer. Inhibiting the expression of PHD-finger4 increased the length and diameter of main vein. Nevertheless, the molecular mechanism of PHD-finger4 regulating the development of leaf main vein is not clear. Consequently, we want to utilized yeast two-hybrid system and bimolecular fluorescence complementation (BiFC) to characterize the interaction between PHD-finger4 and the first-layer other genes. In addition, the regulation relationship between PHD-finger4 and the second-layer genes was verified by using transgenic lines as materials and the chromatin immunoprecipitation (ChIP) and PCR amplification as techniques. Finally, we will clone and transform UTL1-1, AS2 and YAB1 genes in the second layer, and analyze the relationship between these genes and the third-layer genes by ChIP-seq. This research will reveal the mechanism of PHD-finger4 regulating leaf main vein development by studying the regulatory relationship between PHD-finger4 and other genes in each layer of the network, and provide a reference for molecular design breeding of leaves in birch.