Nutritional Control of Root Architectural Traits

Root growth and development are of outstanding importance for maintaining plant performance, especially under adverse soil conditions. When nutrients are sparingly available or unevenly distributed, plants can alter the degree of root branching and/or the length of different root orders to optimize soil exploration. Such modifications of root architectural traits indicate that nutrient-dependent signals are integrated into developmental processes to reshape the three-dimensional configuration of root systems. However, the identity of the genes involved in this coordination remains still largely elusive. Thus, we have assessed which root development-related (RDR) genes are transcriptionally responsive to nutrient deficiencies in Arabidopsis thaliana. Our results indicate that most nutrient-responsive RDR genes were affected by a single nutrient deficiency. This finding goes along with our observations that nutrients shape distinctively the root system architecture by altering root traits at nutrient-specific degrees. Furthermore, in another study we have found that roots can also exhibit a localized response to the spatially-restricted availability of the micronutrient iron. In this case, the auxin influx carrier AUX1 is involved in diverting the auxin flow into lateral roots to stimulate specifically the elongation of those lateral roots that have access to iron. Although such response is conserved among different natural accessions of A. thaliana, distinct iron levels were necessary to trigger the iron-mediated lateral root elongation depending on the accession line. The identification of more genes associated with the modulation of root architectural traits in response to nutrients will assist breeding efforts for improving crop productivity under reduced fertilizer inputs.