University of Missouri

ABOUT THE LAB

Current data indicate that purinergic signaling can potentially affect every cell in the human body. Indeed, one theory is that extracellular ATP (eATP) is the oldest, extracellular signal involved in cell-cell communication. The mechanisms of purinergic signaling are well-established in mammals and, indeed, support a multibillion-dollar pharmaceutical industry. In contrast, relatively little is known about purinergic signaling in plants or other eukaryotes. Plants do not possess canonical P2X or P2Y purinoreceptors but instead recognize eATP through novel lectin-receptor-like kinases, termed P2K. The lab previously identified two, plant purinoreceptors, P2K1 and P2K2, but data suggest that many others remain to be identified. Their research indicates that purinergic signaling in plants impacts environmental stress responses, increases in cellular calcium levels, as well as reactive oxygen species, metabolism, systemic signaling, growth, and cell death. Hence, purinergic signaling is as ubiquitous and impactful in plants as that found in mammals and, indeed, many of the downstream effects are similar. The differences seen, comparing plants and animals, appear largely due to the unique biochemistry of the P2K receptors. Hence, a key objective of their research is the identification of the full repertoire of plant receptors, including additional P2K-type and, perhaps, other novel purinoreceptor families. The goals of their research are to:

1. Identify additional plant purinergic receptors.
2. Identify other genes/proteins involved in purinergic signaling.
3. Expand studies on purinergic signaling to other plant species.

Since our original identification of the first plant purinoreceptors, the laboratory has been highly productive, greatly expanding its knowledge of eukaryotic purinergic signaling beyond the wealth of information available in mammalian systems. The net result of their work is to provide the comparative data to add to the lab’s overall understanding of purinergic signaling in higher eukaryotes, illustrating differences and similarities, and ultimately laying the basis for opportunities to manipulate these pathways for human benefit.

The long-term goal of the lab’s work is to further fundamental understanding of the agronomically important soybean N2-fixing symbiosis. Soybeans are the major source of nitrogen for livestock feed and are also processed into protein-rich products for human consumption. In 2020, soybean was grown on more than 90 million acres in the U.S. with an estimated value of more than $46 billion. Soybean is a major crop worldwide due to its ability to fix atmospheric N2 through its symbiotic relationship with soil bacteria. It has been estimated that more than 60 million metric tons of N2 are fixed by legumes annually with a fertilizer replacement value of $7-10 billion. Their research group has a specific focus on understanding unique areas of the rhizobial-legume symbiosis that are critical for nodule formation and nitrogen fixation. Collectively, their team brings a unique repertoire of techniques that allow for a detailed functional genomic and biochemical analysis of the nodulation process with precision at the molecular level. The lab’s multi-disciplinary research team brings the necessary expertise in functional genomics, microscopy, biochemistry, mass spectrometry and computational biology to achieve the proposed goals. While the early events in symbiotic establishment are well studied at a genetic level, much less is known about the detailed biochemical processes that define the rhizobial infection process. They will use tools developed in the lab from studies in Arabidopsis to provide a detailed examination of the protein complexes within the root hair cell, which are critical for rhizobium infection. This will include a careful examination of the role of the plant innate immunity response. Surprisingly, given the detailed genetic analysis of nodulation, relatively few studies have explored the biochemistry of the infection process. The ultimate goals will be to expand their understanding of the N2-fixing symbiosis filling in critical gaps in their knowledge that may eventually lead to the successful transfer of nitrogen fixing ability to other plants.