Nitrogen Influence on Lateral Root Development of Brassicaceae Species

Nitrogen (N) fertilization has been used for decades to increase crop yield but excessive concentrations of nitrate are detrimental to the environment. Modifying root architecture of plants to capture N more efficiently could represent a sustainable solution to maintain crop productivity whilst reducing fertilizer input. Nitrate can readily leach through the soil profile and become quickly depleted in surface strata. Therefore, a root system with rapid exploitation of deep soil would optimize the capture of that mobile resource. The goal of our research is to uncover mechanisms of lateral root growth stimulation or repression by nitrate availability in the model species Arabidopsis thaliana and to exploit that knowledge to improve closely related Brassica crops (oilseed rape). Induced and naturally occurring genetic variability of the model species is exploited in order to identify key genes that determine root morphology and root biomass allocation. The information gained about the Arabidopsis genes and their regulatory networks is used to help to pinpoint functionally related genes and pathways in oilseed rape that map within Nitrogen Use Efficiency (NUE) loci. Our concept has proved to be pertinent in laboratory set-ups, as shown by some oilseed rape cultivars displaying both high lateral root length and shoot biomass production at contrasted N inputs. This suggests that high root branching can be a positive NUE indicator, thereby supporting the long-term objective of research. A measurable outcome will be to provide markers for selecting new crop genotypes for smart farming.