Table 1. Model parameters.

Parameter	Description	Value	Unit
Mechanical model component
RAF	AF reorientation rate	0.02	h–1
DAF	AF degradation rate	0.01	h–1
Auxin transport model component
bIAA	basal auxin production rate	0*	nM/h
DIIAA	auxin diffusion rate in the intercellular space	1	μm2/h
dIAAb	basal auxin degradation rate	0.0125, Perianez-Rodriguez et al., 2021	nM/h
dIAAMax	maximum auxin degradation rate coefficient	0.125	h–1
KIAAMax	coefficient for half-max auxin degradation	5	nM
KAUX1	coefficient of auxin importing rate by AUX/LAX	1	μm/h
KPIN	coefficient of auxin export rate by PIN	1.4, Mironova et al., 2010	μm/h
bAUX1	AUX/LAX basal expression	1	nM/h
AUX1expr	auxin-induced AUX/LAX maximal expression	30	nM/h
AUX1K	auxin-induced AUX/LAX half-max expression	0.01	nM
AUX1tr	AUX/LAX trafficking rate	1	h–1
AUX1Max	maximum concentration of AUX/LAX	2	nM
AUX1MaxMem	maximum concentration of AUX/LAX on membrane sections	15	nM
dAUX1	AUX/LAX degradation rate	0.08	h–1
bPIN	PIN basal expression	0.2, Mironova et al., 2010	nM/h
PINexpr	auxin-induced PIN maximal expression	50	nM/h
PINK	auxin-induced PIN half-max expression	0.05	nM
PINtr	PIN trafficking rate	1	h–1
PINMax	maximum PIN concentration inside the cell	2	nM
PINMaxMem	the maximum concentration of PIN on membrane sections	15	nM
dPIN	PIN degradation rate	0.08, Mironova et al., 2010	h–1
dPINmax	maximum PIN degradation rate on membranes	0.8	h–1
kAF	coefficient for AF orientation contribution to PIN sensitivity	†	-
kP	coefficient for auxin flow contribution to PIN sensitivity	3	-
kAFP	coefficient for interaction AF orientation+ auxin flow contribution to PIN sensitivity	3	-
kG	coefficient for cell geometry contribution to PIN sensitivity	3	-
Kaf	half-max AF orientation contribution to PIN sensitivity	0.5	-
Kgeom	half-max cell geometry contribution to PIN sensitivity	0.5	-
PIN polarization parameters
Kflux	auxin-flux half-max contribution on PIN sensitivity	0.1	nM μm
bREG	regulator basal expression	10	nM/h
bPOL	polarizer basal expression	10	nM/h
dPOL	regulator decay rate	0.08	h–1
dREG	polarizer decay rate	0.08	h–1
Kregtr	regulator base trafficking rate	1	h–1
Kpoltr	polarizer base trafficking rate	0.01	h–1
Dreg	regulator diffusion rate	1	μm2/h
Dpol	polarizer diffusion rate	0.1	μm2/h
KdispPOL	polarizer displacement rate	10	h–1
KregIAA	regulator auxin-induced half-max trafficking rate	0.01	nM
KpolIAA	polarizer auxin-induced half-max trafficking rate	0.01	nM
KregGradT	regulator max trafficking rate activation by auxin gradient	1	nM/h
KregGradK	regulator auxin gradient-induced half-max trafficking rate	1	nM
KpolIP	half-max value of polarizer contribution on PIN sensitivity	0.1	nM
Auxin-dependent root growth parameters
kEMax	cell wall maximum stiffness	1	-
K1auxin	half-max cell wall relaxation coefficient by auxin	0.05	nM
K2auxin	half-max cell wall stiffening coefficient by auxin	3	nM

^*auxin basal expression is set to zero for the default wild type model. However, when local production in the QC is necessary, the value is set to 10.

^†this parameter is set to 0 in the default model and included in the formulas only for completeness.