Virtual Root — interactive auxin transport model

shoot end ↑ · ↓ root tip

0µM

hover / tap a cell to inspect it

Presets

Controls

PIN efflux strength (µm/s)

AUX1 influx strength / tip trap (µm/s)

QC auxin production (µM/s)

Auxin decay (1/s)

PIN3/7 level — columella (lower = microgravity)

Gravitropism: bias columella PIN to the lower side Show anatomy labels Show auxin-flux arrows DII-VENUS view (bright = low auxin, as under the microscope)

Try a preset, then watch it converge. Gravistimulate to redistribute auxin to the lower side (the start of root bending); 🛰️ Spaceflight (µG) lowers columella PIN3/7 — as seen in the CARA / OSD-120 ISS root transcriptome — so auxin becomes confined to the QC with no lateral bias. Without a preferred side, the root keeps growing but loses a consistent direction — and flight images confirm it: root-angle dispersion rises in space (OSD-121: 51.2° vs 45.3° on the ground, p < 0.0001). PIN2 / aux1 mutant break the return flow / tip trap. The white arrows trace the auxin reflux loop.