AtOFPs regulate cell elongation by modulating microtubule orientation via direct interaction with TONNEAU2

Area of Science:

• Plant Biology
• Molecular Biology
• Cell Biology

Background:

• OVATE family proteins (OFPs) are plant-specific transcriptional repressors involved in growth regulation.
• OFPs have been shown to interact with TONNEAU1 Recruiting Motif (TRM) proteins, affecting tomato fruit shape.

Purpose of the Study:

• To investigate the role of OFP family proteins in plant cell expansion and microtubule organization.
• To elucidate the interaction between OFPs and microtubule-associated proteins.

Main Methods:

• Generating mutant plants with knock-down OFP expression.
• Overexpressing OFPs in transgenic plants.
• Investigating protein-protein interactions using co-immunoprecipitation.
• Performing genetic analysis to determine the requirement of TON2.

Main Results:

• Knock-down of OFP1, OFP2, OFP3, and OFP5 resulted in longer hypocotyls and cotyledons due to enhanced cell elongation.
• OFP overexpression disturbed cortical microtubule arrays and caused abnormal pavement cell expansion, leading to kidney-shaped cotyledons.
• OFP2 and OFP5 directly interact with TONNEAU2 (TON2), which is essential for OFP function.
• Altering OFP expression affected light and brassinosteroid (BR)-regulated microtubule reorientation, with BR treatment reducing OFP2 accumulation.

Conclusions:

• OFP family proteins negatively regulate cell expansion by modulating microtubule reorganization.
• The function of OFPs in cell expansion is dependent on TONNEAU2 (TON2).
• OFP2 plays a role in mediating brassinosteroid-regulated microtubule reorientation.