RESTORE · Reconstructing the ancestral state of plant symbiotic cell types

Life on land as we know it today would not exist without a key plant innovation 450 million years ago: the ability to form symbiosis with arbuscular mycorrhiza (AM) fungi. Intriguingly, this symbiosis is restricted to specific cell types. For example, in vascular plants arbuscules form in root cortical cells, while in rootless non-vascular plants they occur in aerial tissues such as the thallus in Marchantia paleacea. The fact that this trait evolved once and has been maintained across most extant plants suggests that AM symbiosis competence is an intrinsic cell type property inherited from the most recent common ancestor that first formed this association.To test this hypothesis, RESTORE aims to understand how specific cell types acquired and maintained the competence to host symbionts over hundreds of millions of years by: (i) generating a single-cell transcriptomic atlas of M. paleacea as a model non-vascular plant, (ii) identifying conserved gene regulatory modules from single-cell data of AM-relevant tissues across extant species, refined with phylogenomic analyses, and (iii) functionally validating top candidate regulators in both M. paleacea and the vascular legume Medicago truncatula, assessing their role in AM symbiosis.This interdisciplinary project brings together the host lab’s expertise in evo-devo and plant symbiosis, where M. paleacea has been established as a novel model, with my experience in cross-species single-cell transcriptomics and taking advantage of the growing availability of single-cell datasets. RESTORE will not only establish a new conceptual framework for evo-devo studies considering cellular diversification across species evolution but also provide knowledge to expand symbiotic cell fates in crops, offering new strategies for sustainable agriculture. At the same time, it will strength my profile as an independent researcher at the interface of evo-devo, computational biology and plant-microbe interactions.