Plant cells use auxin efflux to explore geometry

Area of Science:

• Plant biology
• Cell biology
• Biophysics

Background:

• Animal morphogenesis relies on cell movement, while plant development uses cell axis alignment to directional cues.
• Mechanical stress and auxin gradients are key directional inputs in plant tissues.
• Dissecting the roles of mechanical and chemical signals in plant tissues is experimentally challenging.

Purpose of the Study:

• To develop a novel method to isolate the role of chemical signals in plant cell axis alignment.
• To investigate how auxin gradients influence cell orientation independently of mechanical cues.
• To propose a model for touch-independent geometry exploration guided by auxin.

Main Methods:

• A novel experimental system using plant cells without cell walls was created.
• Microfluidic devices were used to generate controlled auxin gradients.
• Rectangular microvessels were integrated orthogonally to the auxin gradient to impose geometric cues.

Main Results:

• Cells aligned their new axis with the microvessel geometry before physical contact.
• Auxin efflux was identified as essential for this touch-independent alignment.
• The study demonstrated that auxin gradients can direct cell axis orientation.

Conclusions:

• Plant cell axis alignment can be directed by auxin gradients, independent of mechanical stress.
• A model is proposed where auxin gradients guide cell axis alignment in tissues with minimal mechanical tension.
• This approach offers a new way to study cell-environment interactions in plant development.