胡杨披针形叶和宽卵圆形叶之间差异表达基因的表观遗传调控机理初探

The poplar species Populus euphratica Oliv. has a typical heterophylly, which associated with growth stages and the external environment, is also regulated by the strict genetic development program. However, the molecular regulation mechanism of P. euphratica heteromorphic leaf genesis is still not clear until today. This project based on the establishment of the transcriptome expression profiles in our previous studies, the lanceolate and broad-oval leaves of P. euphratica under different habitats will be selected as materials, to determine DNA methylation and histone acetylation locus in P. euphratica genome by MeDIP-Seq and ChIP- Seq, respectively, then compare with the sequencing results of transcriptome and microRNAs, finally, obtain the number and the functional categories of differentially expressed genes regulated by DNA methylation and histone acetylation. On the basis of the experimental verification, the networks of epigenetic regulatory in P. euphratica heteromorphic leaf genesis will be preliminary constructed, these results can provide a reference basis for elucidating the molecular mechanism of P. euphratica heteromorphic leaf morphogenesis.

胡杨具有典型的异形叶性，与生长发育阶段和外部环境密切相关，也受严格的遗传发育程序调控。但是目前胡杨异形叶发生的分子调控机制仍不清楚。本项目在前期研究建立的胡杨异形叶发生转录组差异表达谱基础上，以不同生境下的胡杨披针形叶和宽卵圆形叶为材料，利用甲基化DNA免疫共沉淀测序和染色质免疫共沉淀测序技术在全基因组水平上分别查明发生表观修饰的DNA甲基化和组蛋白乙酰化位点，并与转录组和microRNA测序结果进行比较， 明确受DNA甲基化和组蛋白乙酰化调控的差异表达基因数目及其功能和类别，在实验验证的基础上，初步构建胡杨异形叶发生的表观遗传调控网络，为阐明胡杨异形叶形成的分子机理提供参考依据。

本项目以胡杨的条形叶、披针形叶、卵圆形叶和阔卵圆形叶为材料，构建了它们的表观基因组图谱、mRNA表达谱、miRNA表达谱、lncRNA表达谱和circRNA表达谱，并进行了多组学关联分析。我们发现胡杨9328个新mRNA、91个新miRNA、1977个新lncRNA、1379新circRNA；发现胡杨从条形叶到阔卵圆形叶DNA甲基化水平逐渐升高；鉴定出1374个mRNA、19个miRNA、71个lncRNA和2个circRNA与胡杨异形叶发生相关。然后对这些数据时行了关联分析，发现胡杨异形叶发生过程中，139个基因转录受到DNA甲基化位点的调控，其中7个为胡杨异形发生相关mRNA；17个胡杨发生相关miRNA能够影响46胡杨发生相关mRNA的表达；11个lncRNA能通过拮抗7个miRNA来影响27个胡杨异形叶发生相关mRNA的表达；2个circRNA 能通过拮抗9个miRNA来影响27个胡杨异形叶发生相关mRNA的表达。根据上述结果，本项目分析了表观遗传学修饰、非编码RNA、转录因子在胡杨异形叶发生过程中的作用，构建了胡杨异形叶发生的调控网络图，阐明了DNA甲基化影响GA和ABA信号通路中关键基因的表达，miRNA、lncRNA、circRNA和mRNA通过参与植物激素信号通路共同调控胡杨异形叶的发生，这些因素相互之间存在复杂的调控关系。另外，本项目进行过程中还发明了胡杨雌雄鉴定的简便方法，可以用于胡杨苗期的雌雄鉴定。