Parsimonious Model of Vascular Patterning Links Transverse Hormone Fluxes to Lateral Root Initiation: Auxin Leads the Way, while Cytokinin Levels Out
Fig 2
Expression and regulation of the auxin transporters.
(A) Geometric and realistic cross sections used for the simulations. Cells were assigned a “cell type” (shown according to the colour code in Fig 1A) that determined the type and localisation of auxin transporters, in line with experimental data. (B) Localisation of the influx transporter. (C) Localisation of the efflux transporter in the outer layers. (D–F) localisation of PIN1, PIN3 and PIN7 in the stele of simulated roots, in accordance with experimental observations [3]. Membranes marked in blue have the potential to express a transporter; lighter colour indicates a lower maximum expression level. (G, H) Response curves for hormonal (G) upregulation and (H) downregulation of the auxin transporters. The expression of PIN3, which is simply upregulated by auxin, is Eup([auxin]); since PIN1 and PIN7 are upregulated by cytokinin and repressed by auxin (via AHP6), their expression level is calculated as Eup([cytokinin])*Edown([auxin]). (I) A schematic of the model used in the simulations.