Repressive AUXIN RESPONSE FACTORs contribute to different aspects of totipotency in Marchantia polymorpha.  

Eduardo Flores‐Sandoval, D Magnus Eklund, Syuan‐Fei Hong, John P Alvarez, Tom J Fisher, Edwin R Lampugnani, John F Golz, Alejandra Vázquez‐Lobo, Tom Dierschke, Shih‐Shun Lin, John L Bowman

The evolutionary transition of embryophytes from charophycean algal-like ancestors involved several developmental shifts in both gametophytic and sporophytic generations. Some of these changes included the specification and maintenance of a stem cell niche in both haploid and diploid generations. We report that AUXIN RESPONSE FACTOR transcriptional repressors (Class B and C ARFs) contribute to the establishment of different aspects of totipotency in gametophytic meristems. Class B ARFs are land plant-specific and are essential for meristematic maintenance, competing with the class A ARF activators downstream of exogenous auxin signalling.  Class C ARFs evolved before the origin of land plants and remained independent of the auxin-signalling pathway at least in the liverwort ancestor. Meanwhile, Class C ARFs co-evolved with a repressing microRNA (MIR160) since the origin of embryophytes and modulate the balance of totipotent versus differentiated cell states in multiple developmental contexts, including reproductive transitions. I present that ARF re-wiring from pre-exisitng components in streptophyte ancestors was as major contributor to the establishment of the land plant lineage.

Presenting Author:  Eduardo Flores‐Sandoval

Author Affiliation: School of Biological Sciences, Monash Uni, Melbourne VIC 3800