如何高效发掘多年生木本植物种质资源蕴藏的优异表观等位基因并对其遗传效应进行精确解析是构建多年生木本植物核心种质亟需解决的关键科学问题。本项目以毛白杨优异种质资源（528个体）为材料，基于已完成的种质资源群体重测序、重硫酸盐测序工作，系统开展：（1）毛白杨种质资源群体表观遗传多样性及遗传结构分析；（2）全基因组表观遗传变异位点的加性、显性与上位性效应解析；（3）DNA甲基化等位位点表达模式分析；（4）利用CRISPR-dCas9技术解析DNA甲基化遗传转录调控机制。研究结果将揭示毛白杨优异种质资源表观遗传变异规律，解析毛白杨种质资源全基因组表观遗传变异位点的联合遗传效应，阐明表观遗传变异位点的遗传转录调控机制。通过项目的设施，将为多年生木本植物种质资源评价、保护与利用提供前沿理论和技术支撑，具有重要的科学价值。

Detection and dissection of epiallelic variations of perennial woody plants germplasm resources and further application of the epigenetic variation for core germplasm selection, is important in protection and utilization of germplasm resources of perennial woody plants. In our project, combining with the genome re-sequencing and bisulfate- sequencing data of Populus tomentosa, we use 528 individuals of germplasm populations from P. tomentosa to systematically launch several research topics as follows: 1) Analysis of epigenetic diversity and epi-population structure ; 2) Identification of additive, dominant, and epistatic effects, and their joint effects, and haplotypic effects of genome-wide epigenetics variations, respectively; 3) Genome wide analysis of expression patterns of epiallelic variations; 4) Analysis of DNA methylation genetic transcription regulatory mechanism using CRISPR-dCas9 technology. Therefore, our study could reveal the epigenetic variation regulation of P. tomentosa germplasm populations, dissect the genome-wide combined effects, including additive, dominant and epistatic effects, of phenotypic variation in germplasm resources of P. tomentosa, elaborate epigenetic transcription regulatory mechanism and establish high-effective theory and strategy for applied core collections. This work will provide innovative achievements, which have theoretical and practical values, on solving the significant theoretical and technical matters in protection and utilization of germplasm resources of perennial woody plants.