Omic Analysis at the Level of One Single Legume Cell Type to Reveal the Conservation and Divergence of the Regulatory Mechanisms of Gene Transcription

Each plant cell type is characterized by a specific transcriptomic signature. Hence, the multi-cellular complexity of plant tissues is a limitation to our understanding of the molecular mechanisms controlling plant gene expression and, as a consequence, the conservation and divergence of these mechanisms between plant species. To overcome this difficulty, we have established the root hair cell as a simple model system to analyze and compare transcriptional regulatory mechanisms between plants. The main function of this single outgrowing root epidermal cell is the uptake of water and nutrients, and, in legumes, the root hair is also the first cell type infected by rhizobia. Hence, due to these unique features, the root hair cell is used as a model to characterize the molecular mechanisms controlling plant gene expression in response to abiotic and biotic stresses and the evolution of these mechanisms between plant species.

To demonstrate the advantages working on the root hair cell, we will present the results of a comparative transcriptomic and genomic analysis conducted at the level of isolated Arabidopsis thaliana and Glycine max root hair cells. We will describe the evolutionary pathways leading to the transcriptional divergence and conservation of the preferential expression of soybean paralogous and Arabidopsis orthologous genes in root hairs. Taking advantage of this evolutionary study and combining bioinformatics, molecular, cellular and microscopic tools, we will also present results revealing the conservation of the activity of plant promoters and regulatory elements in the root hair cells of different plant species.