EURO-PEC - European Plant Embryology Consortium

Embryogenesis lays down the foundations of the plant body on which postembryonic development elaborates in a repetitive manner. The early embryo of Arabidopsis is a highly suitable system to study key developmental regulators and the context in which they act because of the limited number of cells and their predictable division patterns. This collaborative research project (CRP) addresses molecular mechanisms underlying each of four critical differentiation events that occur consecutively in early embryogenesis: (1) differential specification of embryonic identity versus extra-embryonic, (2) generation of epidermis versus inner cells, (3) formation of vascular tissue and ground tissue precursors, and (4) specification of shoot and root identity including their respective stem- cell system. We will use previously identified key regulators of these events as starting points and identify the context in which they act. We will also perform genome-wide approaches, including transcript profiling in mutant embryos and chromatin immunoprecipitation followed by next-generation sequencing to identify binding sites and biologically meaningful target genes of key transcriptional regulators. Furthermore, we will employ independent cell-type specific transcriptome profiling approaches to help define the global molecular landscape of these key differentiation events. Finally, we will characterize microRNA-mediated post-transcriptional control as a novel layer of regulation in early embryogenesis. This collaboration will identify regulatory frameworks governing embryonic cell differentiation events and interactions between them. In addition to the advanced genome-wide approaches, genetic analysis as well as 3D- and live embryo imaging will be used to define the role of newly identified regulators in early embryonic patterning. The consortium comprises five international partners each with a strong record in studying developmental decisions in the embryo. The partner labs have been instrumental in identifying the key developmental regulators that form the starting point of this CRP. While sharing a strong interest in understanding early plant embryogenesis, all partners study a different key step and have complementary methodological expertise. Findings, materials and technologies will be shared among the partners to create a common basis for dissecting the developmental decisions. Coordination of individual efforts is critical to prevent duplication of work and will enable identification of links between developmental steps. This collaborative project will help to organize and consolidate a competitive European research base for studying the most fundamental building blocks of plant development. This will be the only way forward in generating a comprehensive understanding of the earliest formative events in plant life, and will provide the much-needed basis for rational applications in plant breeding, propagation and biotechnology.

Understanding the genetic mechanisms that control plant development is key to developing novel crops with improved yield traits. Plant development relies on the continuous formation of new organs, each consisting of multiple cell types, by meristems stem cell groups at the growth tips. While meristems are active throughout plant life, they are initially specified in the early embryo. In this collaborative project, five European groups have combined their efforts to dissect the genetic control of tissue and stem cell specification in the early Arabidopsis embryo. Each group focused on a single, crucial aspect of plant development, and generated genome-wide data on cell type-specific gene expression, as well as genomic binding sites for key developmental regulators. The project has delivered new insights into the cellular decisions underlying cell fate specification. New genes have been identified that are activated in the embryonic cell lineage at the earliest stages of embryogenesis, several of which were shown to be important for embryo development. Likewise, sets of genes were identified that are activated either in the first epidermal cells, or in the first precursor of the ground tissue and vascular tissues, and their further analysis will reveal the mechanisms underlying the formation of these tissues. Furthermore, the function of shoot- and root-specifying transcription factors was dissected in the embryo. Finally, the Austrian sub-project has discovered new roles of a class of small RNAs that do not encode for proteins, called microRNAs, in the control of embryo development. The individual subprojects within the EURO-PEC project, as well as the integration of data across subprojects, has provided a rich substrate for future investigations on the molecular and genetic mechanisms controlling plant embryo development, and datasets generated during this project are compiled in a user-friendly open network portal.