UC San Diego

Plants face a variety of stresses in their environment, including nutrient scarcity and infectious diseases. To survive and develop in the face of these stresses, plants have evolved complex regulatory mechanisms to perceive, integrate and respond to stress. However, how regulatory mechanisms for different stresses intersect is often poorly understood. Recently Immunoregulatory RNA-binding protein (IRR) was demonstrated to regulate plant immunity and disease resistance through phosphorylation-dependent interaction with transcripts encoding key regulators of immunity. Intriguingly, RIP-Seq experiments demonstrated that dephosphorylated IRR interacts with transcripts encoding nearly all known regulators of responses to iron starvation, indicating that it may be a phosphorylation-regulated integrator of these two stresses. This project developed tools and genetic resources to probe the potential role of IRR in mediating iron starvation responses with three specific aims: (1) To genotype and propagate insertional mutant lines for use in phenotyping assays, (2) To implement an assay to visualize rhizosphere acidification, a critical plant response to solubilize iron in alkaline conditions, and (3) To deploy an assay to quantify relative levels of iron-solubilizing coumarins secreted from plant roots. These assays are now being deployed to understand whether IRR affects key iron starvation responses and to probe the intersection between immune signaling and nutrient starvation responses in plants.