Inositol Pyrophosphate Phosphatases as Key Enzymes to Understand and Manipulate Phosphate Sensing in Plants

Phosphorus (P) is one of the three major macronutrients that plants need to grow and survive. When P is scarce, plants utilize a network of characterized responses known as the Phosphate Starvation Response (PSR) to remobilize internal stores of P as well as external P from soil. Emerging evidence shows the PSR is regulated by a specialized group of secondary messenger molecules, inositol pyrophosphates (PP-InsP). PP-InsPs and their precursors, inositol phosphates (InsPs), are important for plant abiotic stress responses, hormone signaling, and other stress responses. While PP-InsPs are critical for plant survival, much about the roles of PP-InsPs and how they are regulated remains to be understood. Further, the enzymes responsible for the synthesis of PP-InsPs in plants have been recently discovered; however, not much is known about the enzymes that degrade PP-InsPs in plants. The goal of the work presented herein is to understand critical aspects of the PP-InsP signaling in plants and leverage this information into a P phytoremediation strategy. To achieve this, I have investigated a group of PP-InsP phosphatases and assessed long-term impacts of depleting PP-InsPs in two plant species, Arabidopsis thaliana (Arabidopsis) and Thlaspi arvense (Pennycress). Exploring the impact of plant PP-InsP phosphatases has allowed me to explore critical aspects of PP-InsP sensing that show great promise for informing P remediation strategies.