Specific expression of LATERAL SUPPRESSOR is controlled by an evolutionarily conserved 3' enhancer.

Area of Science:

• Plant developmental biology
• Molecular genetics
• Evolutionary biology

Background:

• Plant architecture is determined by axillary meristems (AMs), which originate from leaf axils.
• The LATERAL SUPPRESSOR (LAS) gene is crucial for AM formation, with specific expression patterns at leaf boundaries.
• Understanding the mechanisms controlling LAS gene expression is vital for comprehending organ boundary definition and meristem initiation.

Purpose of the Study:

• To investigate the regulatory elements controlling the specific expression of the LATERAL SUPPRESSOR (LAS) gene.
• To elucidate the mechanisms establishing precise transcript accumulation in organ boundary regions.
• To explore the evolutionary conservation and functional significance of LAS regulatory sequences.

Main Methods:

• Analysis of deletion constructs within the LAS promoter region.
• Promoter swapping experiments using different promoters (e.g., 35S minimal, PISTILLATA).
• Phylogenetic analysis of LAS orthologs and transcomplementation experiments.

Main Results:

• An essential enhancer element located 3.2 kb downstream of the LAS gene was identified.
• This downstream enhancer is sufficient to confer boundary-specific expression, even with minimal upstream promoters.
• The LAS 3' enhancer also exhibits suppressor functions and is evolutionarily conserved across plant species, including grasses.

Conclusions:

• A highly conserved enhancer/suppressor element downstream of the LAS gene acts as the primary regulatory module for its boundary-specific expression.
• This finding sheds light on the mechanisms controlling organ boundary formation and AM initiation in plants.
• The functional conservation of these regulatory sequences highlights their importance in plant development across diverse species.