Summary of Research Interests

The plant root system provides the plant with water and nutrients and keeps it stably anchored in the soil. Although the root system appears quite complex, in fact it is made up of a single "unit", the root, repeated over and over. Upon germination, a single embryonic root emerges from the seed and grows to become the primary root. Lateral roots that are anatomically nearly identical to the primary root are produced along its length. Over time, lateral roots will form from these lateral roots in turn. The formation of a single lateral root is a highly regulated developmental process. We have studied this process in detail (Malamy and Benfey, 1997a,b), and shown that plants can regulate the formation of a lateral root at multiple developmental stages. (Click here for an overview of lateral root development)

Root systems continue to grow throughout the lifetime of the plant. Different types of root system architectures (ie deep or shallow, highly branched or unbranched) have been described for different plant species. Therefore, there must be species-specific genes that determine how root systems grow. However, we also know that root systems are extremely responsive to environmental conditions such as the availability or distribution of water and nutrients. Therefore, in thinking about how a plant regulates the growth and development of the root system, we must think about intrinsic developmental pathways and environmental sensing/response pathways. To help us think about these mechanisms, we have devised a developmental plasticity model. This model suggests that environmental response pathways act by modulating elements of intrinsic developmental pathways, with the final output being the formation of lateral roots.

Developmental Plasticity Model

To test this model, and to identify some of the key regulators of root system morphology, the Malamy lab has designed several assays to characterize root system growth in response to water and nutrient cues in the model plant Arabidopsis thaliana. We have used these assays to

2) perform forward genetic screens; and

3) study natural variation in root system development.