Root development has been crucial for the success of vascular plants in terrestrial ecosystems, but not all rooting systems evolved from a common ancestor. Fossil evidence suggests that root development evolved independently at least twice over the course of land plant evolution, once within the euphyllophyte lineage, consisting of the seed plants and ferns, and once within the lycophyte lineage. Despite extensive research on seed plant root development, primarily using the model species Arabidopsis thaliana, we still know very little about the molecular pathways that control root development in ferns horsetails or lycophytes.

In contrast to euphyllophytes, lycophyte roots do not branch by forming lateral roots. Instead a duplication of the root apical meristem causes the root tip to branch dichotomously. This duplication is most likely caused by a symmetrical division of the central apical cell around which these meristems are organized. As each of these two daughter apical cells develop into two new root meristems, one root tip becomes two, thereby inducing this pattern of dichotomous branching. 

By combining classical, well established approaches with new, innovative techniques we aim to identify the genes and molecular pathways regulating the formation and duplication of these stem cell niches. We are particularly interested in discovering differences and similarities between lycophyte and euphyllophyte root developmental programs, revealing the essential pathways governing root development across the plant kingdom, as well as uncovering the hitherto hidden diversity of root development programs (Motte et al., 2022; Yang et al., 2023). 

References:

Hans Motte, Tao Fang, Boris Parizot, Wouter Smet, Xilan Yang, Ward Poelmans, Liam Walker, Maria Njo, George W Bassel, Tom Beeckman, Cellular and gene expression patterns associated with root bifurcation in Selaginella, Plant Physiology, Volume 190, Issue 4, December 2022, Pages 2398–2416, https://doi.org/10.1093/plphys/kiac402

Xilan Yang, Ward Poelmans, Carolin Grones, Abdellah Lakehal, Julie Pevernagie, Michiel Van Bel, Maria Njo, Lin Xu, Hilde Nelissen, Bert De Rybel, Hans Motte, Tom Beeckman, Spatial transcriptomics of a lycophyte root sheds light on root evolution, Current Biology, Volume 33, Issue 19, 2023, Pages 4069-4084.e8, ISSN 0960-9822, https://doi.org/10.1016/j.cub.2023.08.030.