Modeling the emergence of polarity patterns for the intercellular transport of auxin in plants

TL;DR

This paper presents a model explaining how auxin transport and PIN protein polarization patterns emerge in plant cells, highlighting the roles of non-linear PIN recycling, noise, and the absence of concentration gradients.

Contribution

It introduces a novel model linking flux sensing to PIN polarization dynamics, showing spontaneous polarization without auxin gradients and the influence of noise on pattern formation.

Findings

Spontaneous PIN polarization occurs with non-linear recycling dynamics.

Ordered polarization patterns are promoted by molecular noise.

No auxin concentration gradient is necessary for polarization emergence.

Abstract

The hormone auxin is actively transported throughout plants via protein machineries including the dedicated transporter known as PIN. The associated transport is ordered with nearby cells driving auxin flux in similar directions. Here we provide a model of both the auxin transport and of the dynamics of cellular polarisation based on flux sensing. Our main findings are: (i) spontaneous intracellular PIN polarisation arises if PIN recycling dynamics are sufficiently non-linear, (ii) there is no need for an auxin concentration gradient, and (iii) ordered multi-cellular patterns of PIN polarisation are favored by molecular noise.