A Myb-dominated gene regulatory network universally controls sexual cell fate transitions in diatoms

Yet, the regulation of their complex size-dependent life cycles remains obscure. Here, we leveraged single-cell transcriptomics and transgenic reporter lines to uncover the molecular mechanisms behind partner recognition, nuclear fusion, and the remarkable 15-fold size expansion of auxospores.

Gene regulatory network inference revealed that the irreversible commitment to differentiate into gametes is controlled by Myb transcription factors, irrespective of the diel light regime. The sex-specificity of these Mybs across diatom clades and their activity in the global ocean underscores their significance for ploidy transitions in diatoms. These findings reinforce microalgae as powerful models to study cell fate transitions and provide a mechanistic framework for the life cycle dynamics that underpin the functioning of aquatic systems worldwide.