Chapter 2 - Root System Architecture

Abstract

Plants develop most organs post-embryonically, which allows the incorporation of environmental information into decisions concerning when and where to produce new organs. This developmental plasticity is evident in the plant root system, which in dicotyledonous plants such as Arabidopsis thaliana is mostly comprised of lateral and adventitious roots that develop along the length of the primary root. The rate of primary root growth and the location, spacing and growth rate of lateral roots are influenced by the availability of environmental cues such as water and nutrients, which can have dramatic effects on the final architecture of the root system. These environmental responses must intersect with the intrinsic developmental programme of the plant, which is responsible for the general formation and maintenance of the root system. The final root system architecture of any plant is then the product of both intrinsic and environmental response pathways. Carbohydrates and plant hormones such as auxin and cytokinins are required for both intrinsic root development and modulating root system architecture in response to different growth conditions, thus facilitating the optimisation of root growth in complex, heterogeneous environments.