Signaling pathways controlling legume root system development
Plant adaptation to changing environmental conditions largely depends on root system developmental plasticity : depending on water and nutrient availability, as well as biotic and abiotic stresses, the root system architecture is modified by dynamically regulating organ growth, number and distribution. In addition to the formation of lateral roots, legume plants are able to form under soil nitrogen limiting conditions another root lateral organ, the nitrogen-fixing nodule (for reviews see Crespi and Frugier, 2008 ; Gonzalez-Rizzo et al., 2009). This legume-specific organogenesis is induced in response to a symbiotic interaction with bacteria collectively referred to as Rhizobia.
We are interested in understanding mechanisms allowing legumes to coordinate root and nodule development depending on changing environmental conditions : nutrient availability, such as nitrate ; abiotic stresses such as salt or drought ; root pathogens or symbionts. This is critical both to improve yield stability of legume crops used in sustainable agriculture, as well as for understanding bottlenecks that restrict symbiotic nitrogen-fixing nodule organogenesis to legume plants, in the perspective of transferring this capacity to other crops.
In this goal, reverse and forward genetic approaches allowed us to identify in the Medicago truncatula model legume different signaling pathways regulating legume root system development depending on environmental cues.