The BNB-GLID module regulates germline fate determination in Marchantia polymorpha

Area of Science:

• Plant developmental biology
• Evolutionary genetics
• Reproductive biology

Background:

• Germline fate determination in plants involves reprogramming somatic cells, a process poorly understood in land plant evolution.
• The genetic underpinnings of germline specification and its evolutionary trajectory remain largely unknown.

Purpose of the Study:

• To identify key regulators of germline fate determination in the liverwort Marchantia polymorpha.
• To investigate the evolutionary conservation and functional divergence of germline specification genes.

Main Methods:

• Gene knockout and overexpression studies in Marchantia polymorpha.
• Analysis of gene orthologs in Arabidopsis thaliana.
• Promoter binding assays to investigate gene regulation.

Main Results:

• The GERMLINE IDENTITY DETERMINANT (GLID) protein is essential for germline initiation in Marchantia polymorpha; its loss results in the absence of gametes.
• Overexpression of MpGLID induces male germline cell formation in male thalli.
• MpBONOBO (BNB) activates MpGLID by direct promoter binding, inducing male germ cell-like cells.
• The Arabidopsis ortholog AtMS1 cannot rescue MpGLID function, indicating functional divergence.

Conclusions:

• The BNB-GLID module is an ancient regulatory system for germline determination in land plants.
• This module is conserved in bryophytes but has been functionally rewired in flowering plants, primarily for tapetum development.
• The study sheds light on the evolution of germline specification and its genetic control across land plants.