Abstract Detail

Advances in Modelling Plant Development

Dupouy, Lionel X. [1], Silk, Wendy K. [2].

Models of Bacterial Colonization of Root Tips Must Include Root Development.

Microbial activity in the rhizosphere contributes to nutrient bioavailability and crop growth, as well as soil biodiversity and soil structure. Successful microbial colonization of the rhizosphere requires early establishment on growing root surfaces to benefit from root exudates. Root growth and developmental gradients in root properties influence the establishment and functioning of the rhizosphere. Three points of view are relevant. From the point of view of the moving root tip we see a chemical field surrounding the tip as the tip moves to deeper soil layers. A complementary perspective is the point of view of the stationary soil particle that will eventually lie beside a mature root cell. The fixed soil particle will experience the processes (efflux or uptake) associated with a neighboring root element, so that fluxes corresponding to the different root locations will be encountered in a predictable sequence. For instance if the root tip is moving 0.5 mm h^-1 downward, every half-hour the flux into or from the soil particle will be for a root element that is located 0.25 mm farther from the root tip. The third perspective is that of a particle attached to a cell initially on the surface of the root tip. This is the Lagrangian specification of root interaction with the soil. With time the cellular particle accelerates away from the tip to reach a displacement velocity equal to the root elongation rate, as the cell decelerates to a final fixed location in the soil profile. Working simultaneously in the moving reference frame attached to the root tip and the stationary reference frame of the soil horizon is essential to understanding rhizosphere development and soil impacts on plants, yet few rhizosphere studies in the literature take root growth into account. Here, we summarize a new model for bacterial colonization of a growing root. We investigate interactions taking place between the root surface and bacteria when a root tip enters unexplored regions of soil. We present a theoretical framework that generalizes prevailing approaches for describing root cell kinematics, bacterial growth, and adhesion on root surfaces. The model shows that key traits for successful microbial colonization are root elongation rate, bacterial attachment rate and root cap carrying capacity.

1 - The James Hutton Institute , , Invergowrie Dundee, Scotland, DD2 5DA, UK
2 - University Of California Davis, Dept Of Land Air & Water, One Shields Ave., Davis, CA, 95616-8627, USA

Keywords:
rhizosphere
root tip
root growth
bacterial colonization
Lagrangian specification
Development
plant microbe interactions.

Presentation Type: Symposium Presentation
Session: SY10
Location: Salon 13/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 1:45 PM
Number: SY10002
Abstract ID:128
Candidate for Awards:None