Impact of the Environment on Root Architecture in Dicotyledoneous Plants

Root architecture plays an important role in water and nutrient acquisition and in the ability of the plant to adapt to the soil. Lateral root growth and development is the main determinant of the shape of the root system, a trait controlled by internal cues and external factors. In this chapter, we discuss the impact of abiotic stresses, mainly drought and salt, on the action and number of root meristems to determine root architecture. In addition to Arabidopsis, we discuss recent results on model legumes able to interact symbiotically with soil rhizobia to form new meristems leading to the nitrogen-fixing nodule. The molecular mechanisms regulating lateral root initiation and emergence as well as root nodule formation in legumes allow plants to coordinate root growth with the soil environment.