Dynamic chromatin accessibility deploys heterotypic cis/trans-acting factors driving stomatal cell-fate commitment

Area of Science:

• Plant biology
• Developmental biology
• Genetics

Background:

• Chromatin architecture and transcription factor (TF) binding are crucial for cell-fate specification during development.
• The precise regulatory interplay between chromatin dynamics and TF binding in lineage progression is not fully understood.

Purpose of the Study:

• To map the dynamic chromatin landscapes during stomatal cell-lineage progression.
• To elucidate the roles of lineage-specific bHLH TFs in governing cell-state transitions.
• To uncover the mechanisms of TF-mediated chromatin regulation in cell-fate commitment.

Main Methods:

• Atlas generation of dynamic chromatin landscapes.
• Identification of co-cis regulatory elements (CREs) and TF binding motifs.
• Analysis of TF complex formation and recruitment of chromatin modifiers.

Main Results:

• Major chromatin accessibility reprogramming occurs during the proliferation-to-differentiation transition.
• Novel co-CREs with BBR/BPC (GAGA) and bHLH (E-box) motifs were identified for the early precursor stage.
• Master-regulatory bHLH TFs SPEECHLESS and MUTE consecutively bind to initiate and terminate proliferation.
• BPC TFs complex with MUTE to repress SPEECHLESS expression via histone modifications.

Conclusions:

• Cell-state-specific heterotypic TF complexes facilitate cell-fate commitment.
• TF complexes recruit chromatin modifiers through key co-CREs to regulate developmental transitions.
• This work provides a mechanistic understanding of chromatin regulation in cell-lineage progression.