Expression atlas of Selaginella moellendorffii provides insights into the evolution of vasculature, secondary metabolism and roots

Selaginella moellendorffii is a representative of the lycophyte lineage and is studied to understand the evolution of land plant traits such as the vasculature, leaves, stems, roots, and secondary metabolism. However, only few studies investigated about the gene expression and transcriptional coordination of Selaginella genes, precluding us from understanding the evolution of transcriptional programs behind these traits. We present a gene expression atlas comprising all major organs, tissue types, and the diurnal gene expression profiles for S. moellendorffii. We show that the transcriptional gene module responsible for the biosynthesis of lignocellulose evolved in the ancestor of vascular plants, and pinpoint the duplication and subfunctionalization events that generated multiple gene modules involved in the biosynthesis of various cell wall types. We demonstrate how secondary metabolism is transcriptionally coordinated and integrated with other cellular pathways. Finally, we identify ...