Paf1复合体控制萼片三维形态的分子机制

器官三维形态建成是发育生物学的难点和重要科学问题。拟南芥萼片是研究植物器官形态建成的模式系统。申请人前期研究筛选到若干拟南芥萼片三维形态异常突变体，测序分析表明它们是Paf1（RNA聚合酶相关因子1）复合体基因发生突变造成。Paf1复合体参与RNA聚合酶II的转录过程，在发育过程中起重要作用。本项目以Paf1复合体基因VIP4为例，研究其控制拟南芥萼片弯曲度的细胞学和分子机制。一方面采用活体实时成像、生物力学分析和计算机模拟，研究vip4突变影响萼片弯曲度的细胞学机制。另一方面以RNA-seq结合ChIP-seq等大规模手段研究VIP4靶基因，并筛选vip4突变体的抑制基因，通过研究VIP4靶基因和抑制基因的功能及其互作机制，阐明VIP4控制萼片发育的分子机制。本研究将有助于解析植物器官三维形态建成，深化对植物器官功能的认识，具有重要的理论价值。

Understanding three-dimensional morphogenesis is a key scientific question and also a difficult question in the developmental biology field. The Arabidopsis sepal has been established as a model system for studying plant organ morphogenesis. We have screened out several Arabidopsis mutants with deformed three-dimensional sepal morphology. These mutants have sepals curved outwards, compared with the inwards-curved wild-type sepals. Through mapping by sequencing we found that these mutants were all caused by mutations in genes encoding components of the polymerase-associated factor 1 complex (Paf1 complex). Paf1 complex play prominent roles in regulating gene expression via modulating chromatin structure and controlling transcription. In this project, we are going to elucidate the mechanism of how Paf1 complex genes control sepal curvature, by investigating the vip4 mutant, which has a mutation in one of the Paf1 complex genes VIP4. Live-imaging and other microscopic techniques as well as computer simulation will be employed to study the mechanism of abnormal sepal curvature in the vip4 mutant on molecular and cellular levels. In the meantime, RNA-seq combined with ChIP-seq will be utilized to identify VIP4 target genes. Further, a suppressor screen using radio-mutagenized vip4 seeds will be carried out to study genes involved in VIP4-regulated sepal development. By studying the function of the VIP4 target genes and suppressor genes as well as the relations between these genes and VIP4, a regulatory network involved in Paf1 complex genes’ controlling of sepal morphogenesis will be established. Our proposed project will advance the research on three-dimensional organ morphogenesis in plants, lead to a deep understanding of the function of plant organs, and generate significant scientific value.