A PLETHORA3/7 transcription factor shapes cucumber shoot architecture

Area of Science:

• Plant developmental biology
• Molecular genetics
• Transcriptomics

Background:

• PLETHORA (PLT) transcription factors are key regulators of plant shoot development.
• Previous studies in Arabidopsis and tomato suggest PLTs control phyllotactic regularity and branching.
• The roles of PLTs in other plant species remain largely unknown.

Purpose of the Study:

• To investigate the function of PLETHORA transcription factors in cucumber (Cucumis sativus) shoot development.
• To determine if CsPLTs exhibit conserved or diversified roles compared to PLTs in other species.

Main Methods:

• Phylogenetic analysis of CsPLT homologs.
• Transcriptomic profiling of CsPLT expression domains.
• Genome-wide in vitro binding assays (DAP-seq) to identify target genes.
• Phenotypic analysis of cucumber TILLING mutants for CsPLT genes.

Main Results:

• CsPLT3/7 and CsPLT5 are expressed in complementary domains within the cucumber shoot apex.
• CsPLTs bind to an ANT-like motif and regulate Shoot Apical Meristem (SAM)-organizing genes.
• Csplt3/7 mutants display severe defects, including a flattened apex, altered internode length, stem architecture, flower morphology, and axillary organ initiation.
• Mutant phyllotaxis shifted from spiral towards distichous orientation.

Conclusions:

• The PLT3/7 clade plays crucial roles in cucumber shoot apical meristem formation and subsequent development.
• Cucumber PLTs exhibit both conserved functions (SAM organization) and diversified roles (specific architectural traits) in shoot development.
• This study provides evidence for conserved and divergent functions of PLT3/7 across plant families.