Genome wide association to test how different nitrogen sources regulate growth and defense metabolism

The dichotomy of nitrogen’s essentialness for life and limited availability means that it is a key component in any effort to maintain or increase crop yields. Because Nitrogen is a core component of amino acids, it is a critical element for plant growth. Additionally, amino acids are the building blocks for a large number of defense metabolites like the glucosinolates in Brassicas. Thus, the proper mobilization of nitrogen is also essential to ensure defense against herbivores and pathogens. Thus, coordinating growth and defense requires the efficient use of nitrogen to maximize productivity while still being responsive to environmental threats. Work is beginning to test how Nitrogen, specifically nitrate, and growth are linked, and there is little information on the integration of nitrogen availability and defense metabolism in plants. There is even less known about how differences in nitrate vs ammonia may shift this coordination.

To test how nitrogen level and source link with defense metabolism we measured growth and glucosinolates on 1,135 Arabidopsis thaliana natural accessions on two different concentrations of nitrate and ammonia. Genome wide association is allowing us to identify genes that coordinate these processes and show that regulatory genes and effects vary depending on the nitrogen source. These genes will allow us to understand and potentially manipulate these responses to increase plant productivity and defense.