KAI2-dependent signaling controls vegetative reproduction in Marchantia polymorpha through activation of LOG-mediated cytokinin synthesis (14).

Marchantia polymorpha reproduces vegetatively (asexually) by producing propagules known as gemmae within gemma cups and sexually through spores. We previously reported that KARRIKIN INSENSITIVE2 (KAI2)-dependent signaling promotes gemma cup and gemma formation. KAI2A perceives unidentified endogenous ligand(s), tentatively referred to as KAI2 ligands (KL).

Auxin signaling is essential for organogenesis but not for cell survival in the liverwort Marchantia polymorpha.

Auxin plays pleiotropic roles in plant development via gene regulation upon its perception by the receptors TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALING F-BOX (TIR1/AFBs). This auxin-regulated transcriptional control mechanism originated in the common ancestor of land plants. Although the complete loss of TIR1/AFBs causes embryonic lethality in Arabidopsis thaliana, it is unclear whether the requirement for TIR1-mediated auxin perception in cell viability can be generalized.

An ancestral function of strigolactones as symbiotic rhizosphere signals.

In flowering plants, strigolactones (SLs) have dual functions as hormones that regulate growth and development, and as rhizosphere signaling molecules that induce symbiosis with arbuscular mycorrhizal (AM) fungi. Here, we report the identification of bryosymbiol (BSB), an SL from the bryophyte Marchantia paleacea. BSB is also found in vascular plants, indicating its origin in the common ancestor of land plants.

Diminished Auxin Signaling Triggers Cellular Reprogramming by Inducing a Regeneration Factor in the Liverwort Marchantia polymorpha.

Regeneration in land plants is accompanied by the establishment of new stem cells, which often involves reactivation of the cell division potential in differentiated cells. The phytohormone auxin plays pivotal roles in this process. In bryophytes, regeneration is enhanced by the removal of the apex and repressed by exogenously applied auxin, which has long been proposed as a form of apical dominance.

Auxin Biology in Bryophyta: A Simple Platform with Versatile Functions.

Bryophytes, including liverworts, mosses, and hornworts, are gametophyte-dominant land plants that are derived from a common ancestor and underwent independent evolution from the sporophyte-dominant vascular plants since their divergence. The plant hormone auxin has been shown to play pleiotropic roles in the haploid bodies of bryophytes. Pharmacological and chemical studies identified conserved auxin molecules, their inactivated forms, and auxin transport in bryophyte tissues.

Design principles of a minimal auxin response system.

Auxin controls numerous growth processes in land plants through a gene expression system that modulates ARF transcription factor activity. Gene duplications in families encoding auxin response components have generated tremendous complexity in most land plants, and neofunctionalization enabled various unique response outputs during development. However, it is unclear what fundamental biochemical principles underlie this complex response system.

Positional cues regulate dorsal organ formation in the liverwort Marchantia polymorpha.

Bryophytes and vascular plants represent the broadest evolutionary divergence in the land plant lineage, and comparative analyses of development spanning this divergence therefore offer opportunities to identify truisms of plant development in general. In vascular plants, organs are formed repetitively around meristems at the growing tips in response to positional cues. In contrast, leaf formation in mosses and leafy liverworts occurs from clonal groups of cells derived from a daughter cell of the apical stem cell known as merophytes, and cell lineage is a crucial factor in repetitive organ formation.

The Roles of the Sole Activator-Type Auxin Response Factor in Pattern Formation of Marchantia polymorpha.

Cell division patterning is important to determine body shape in plants. Nuclear auxin signaling mediated by AUXIN RESPONSE FACTOR (ARF) transcription factors affects plant growth and development through regulation of cell division, elongation and differentiation. The evolutionary origin of the ARF-mediated pathway dates back to at least the common ancestor of bryophytes and other land plants.