Physcomitrium patens: A Single Model to Study Oriented Cell Divisions in 1D to 3D Patterning

Abstract

Development in multicellular organisms relies on cell proliferation and specialization. In plants, both these processes critically depend on the spatial organization of cells within a tissue. Owing to an absence of significant cellular migration, the relative position of plant cells is virtually made permanent at the moment of division. Therefore, in numerous plant developmental contexts, the (divergent) developmental trajectories of daughter cells are dependent on division plane positioning in the parental cell. Prior to and throughout division, specific cellular processes inform, establish and execute division plane control. For studying these facets of division plane control, the moss Physcomitrium (Physcomitrella) patens has emerged as a suitable model system. Developmental progression in this organism starts out simple and transitions towards a body plan with a three-dimensional structure. The transition is accompanied by a series of divisions where cell fate transitions and division plane positioning go hand in hand. These divisions are experimentally highly tractable and accessible. In this review, we will highlight recently uncovered mechanisms, including polarity protein complexes and cytoskeletal structures, and transcriptional regulators, that are required for 1D to 3D body plan formation.

Mosses: Accessible Systems for Plant Development Studies

“…Such studies greatly benefit of the accessibility to single cells in a multicellular context. For instance, asymmetric and directional cell divisions are key life developmental tools to build an organism, but we lack understanding on how these processes are exactly controlled and regulated [12]. Importantly, these developmental drivers are shared between mosses and vascular plants, and to some extent with animals, and associated gene functions seem to be highly conserved despite the long period of independent evolution [13].…”

Control of Arabidopsis shoot stem cell homeostasis by two antagonistic CLE peptide signalling pathways

“…Overall meristem size is restricted by the ERECTA-family signalling pathway, which is activated by EPIDERMAL PATTERNING FACTOR (EPF)-LIKE (EPFL) ligands from the meristem periphery and confines both CLV3 and WUS expression ( Mandel et al, 2014 ; Shpak, 2013 ; Shpak et al, 2004 ; Torii et al, 1996 ; Zhang et al, 2021 ). In the land plant lineage, the shoot meristems of bryophytes such as the moss Physcomitrium patens appear less complex than those of angiosperms and carry only a single apical stem cell which ensures organ initiation by continuous asymmetric cell divisions ( de Keijzer et al, 2021 ; Harrison et al, 2009 ). Broadly expressed CLE peptides were here found to restrict stem cell identity and act in division plane control ( Whitewoods et al, 2018 ).…”

Control of Arabidopsis shoot stem cell homeostasis by two antagonistic CLE peptide signalling pathways

“…Overall meristem size is restricted by the ERECTA-family signalling pathway, which is activated by EPIDERMAL PATTERNING FACTOR (EPF)-LIKE (EPFL) ligands from the meristem periphery and confines both CLV3 and WUS expression (Mandel et al, 2014; Shpak, 2013; Shpak et al, 2004; Torii et al, 1996; Zhang et al, 2021). In the land plant lineage, the shoot meristems of bryophytes such as the moss Physcomitrium patens appear less complex than those of angiosperms, and carry only a single apical stem cell which ensures organ initiation by continuous asymmetric cell divisions (de Keijzer et al, 2021; Harrison et al, 2009). Broadly expressed CLE peptides were here found to restrict stem cell identity, and act in division plane control (Whitewoods et al, 2018).…”