Dr. Siobhan Brady
University of California, Davis
Innovation, conservation, and repurposing of gene function in plant root cell type development
Irrespective of species, plant roots have remarkably similar patterning, and thus, many cell types are considered functionally homologous across species. Despite these similarities, there is also diversity in root cell types, such as the exodermis, which is present in a reported 89% of angiosperms, but absent in the intensely studied model species Arabidopsis (Perumalla, Peterson, and Enstone 1990). Additionally, multiple cortical cell types exist in species like tomato and rice (Henry et al. 2015), but only a single cortical cell type exists in Arabidopsis. To understand this diversity we profiled tomato root cell type translatomes and chromatin accessibility. Using xylem differentiation in tomato, relative to Arabidopsis, examples of functional innovation, repurposing and conservation of transcription factors are described. Repurposing and innovation of genes are further observed within an exodermis regulatory network and illustrate its function. Finally, we extend these comparisons between Arabidopsis and tomato, to rice, and explore the question of homology between cell types across diverse species.