Chalmers Conferences, 9th European Conference on Mathematical and Theoretical Biology

Mathematical modeling of auxin transport in root meristem of pin mutants
Victoria V Mironova, Fedor Kazantsev

Last modified: 2014-06-09


Plant hormone auxin acts as a morphogen in regulation of tissue patterning. In the root, auxin response maxima mark the positions of the root apical meristem (RAM) initiation and functioning. Auxin distribution pattern in the RAM is formed due to active transportation through PIN family carriers located on a plasma membranes. Despite the key role of PINs in the auxin gradient establishment, the RAM may compensate knockout of one of them. It has been shown that in pin mutants, the rest PIN paralogs change their expression domains so that to compensate an absence of one of them (Vieten et al., 2005). We investigated this effect by mathematical modeling.

For this purpose we modified our previously published model for auxin transport in the RAM (Mironova et al., 2012). In the model, we simulated auxin distribution in the rectangular cell layout MxN by means of auxin active transport and diffusion. Auxin flow from the shoot was the only source of auxin in the cell layout. Four auxin transporters were considered in the model: PIN1-PIN4. The level of PIN transporters was calculated as the functions dependent on auxin itself. The functions were calibrated using experimental data on auxin treatment of roots in PIN::PIN-GFP plants (Vieten et al., 2005).

First, we adjusted the model parameters to get auxin response maximum in the 5th cell from the root end from zero initial conditions. Second, expression of one of the auxin transporter was switched off and the model was recalculated with the basic set of parameters and zero initial conditions. For all pin1, pin2, pin3 and pin4 mutants, we were able to get the new stationary solution with the auxin maximum in the 5th cell by attenuating only one parameter – auxin flow from the shoot. Our results shows that auxin-dependent PIN expression provide for both: (1) tissue-specific PINs expression in the RAM; (2) compensation of an absence of one of PINs in pin mutants.

Vieten et al. (2005). Functional redundancy of PIN proteins is accompanied by auxin-dependent cross-regulation of PIN expression. Development, 132(20), 4521-4531

Mironova et al. (2012). Combined in silico/in vivo analysis of mechanisms providing for root apical meristem self-organization and maintenance. Annals of botany, 110(2), 349-360.


mathematical model, auxin, root, morphogenesis