Root responses to abiotic stress - a comparative look at root system architecture in maize and sorghum.

Under all environments, roots are important for plant anchorage and acquiring water and nutrients. However, there is a knowledge gap as to how root architecture contributes to stress-tolerance in a changing climate. Two closely related plant species, maize and sorghum, have distinct root system architectures and different levels of stress-tolerance, making comparative analysis between these two species an ideal approach to resolve this knowledge gap. However, the current research has focused on shared aspects of the root system that are advantageous under abiotic stress conditions as opposed to differences. Here we summarize the current state of knowledge comparing the root system architecture relative to plant performance under water deficit, salt stress, and low phosphorus in maize and sorghum. Under water deficit, steeper root angles and deeper root systems are proposed to be advantageous for both species. In saline soils, a reduction in root length and root number has been described as advantageous, but this work is limited. Under low phosphorus (P), root systems that are shallow and wider are beneficial for topsoil foraging. Future work investigating the differences between these species will be critical for understanding the role of root system architecture in optimizing plant production for a changing global climate.