Three-Dimensional Morphological Analysis Revealed the Cell Patterning Bases for the Sexual Dimorphism Development in the Liverwort Marchantia polymorpha.

This article focuses on the cellular and molecular mechanisms underlying sexual dimorphism development in the gametophyte generation of the liverwort Marchantia polymorpha. Using three-dimensional confocal imaging and computational cell segmentation, the study reveals that germline precursor cells, marked by MpBONOBO (MpBNB) expression, are specified at very early stages of sexual branch (gametangiophore) formation, with distinct spatial distribution patterns between males and females. The female-specific transcription factor MpFGMYB regulates female sexual differentiation from these initial stages, as loss-of-function Mpfgmyb mutants exhibit male-like germline precursor distribution and gametangiophore morphology. The findings suggest that in M. polymorpha, germline specification and sexual morphogenesis are tightly coupled processes, contrasting with the sequential development observed in sporophyte-dominant flowering plants.