Salt-stress regulation of root system growth and architecture in Arabidopsis seedlings.

In order to acclimate to the soil environment, plants need to constantly optimize their root system architecture for efficient resource uptake. Roots are highly sensitive to changes in their surrounding environment and root system responses to a stress such as salinity and drought can be very dynamic and complex in nature. These responses can be manifested differentially at the cellular, tissue, or organ level and between the types of roots in a root system. Therefore, various approaches must be taken to quantify and characterize these responses. In this chapter, we review methods to study basic root growth traits, such as root length, cell cycle activity and meristem size, cell shape and size that form the basis for the emergent properties of the root system. Methods for the detailed analysis of lateral root initiation and postemergence growth are described. Finally, several live-imaging systems, which allow for dynamic imaging of the root, will be explored. Together these tools provide insight into the regulatory steps that sculpt the root system upon environmental change and can be used as the basis for the evaluation of genetic variation affecting these pathways.