Functional and Systems Biology

Understanding a Key Metabolic Pathway in Plants

Scientists delve deeper into an important plant cellular pathway that affects plant defense, growth and development, and adaptation to stressors.

May 23, 2022

This study makes significant strides in understanding one such pathway, the MVA pathway, which is extremely important to plant health. (Illustration by Nathan Johnson | Pacific Northwest National Laboratory)

The Science

Plants constantly face stressors from threats such as herbivores, pathogens, and environmental changes, but they have important metabolic processes in place to help fend off and adapt to these stressors. This study investigated one such process known as the mevalonate (MVA) pathway in a small flowering plant commonly used in experimental studies. While the importance of this pathway is well understood in animals, it is less so in plants. Researchers used a method called forward genetic screening, which uses genetic mutations to identify how the targeted genes affect an organism, and showed that for this model plant, a high energy-containing molecule transfers its energy to mevalonate kinase, the key MVA pathway enzyme involved in the response of this plant to stress.

The Impact

This study highlights how critical the MVA pathway is in plant metabolic signaling processes. It also underscores how a form of extracellular signaling, known as purinergic signaling, has a wide-ranging and significant impact on many plant processes. Overall, this work closes a significant knowledge gap related to this key pathway in plant metabolism, whose regulation is universally important to plant health. In addition, the connections made in this study may unveil new genetic targets for engineering crops to increase yield or better survive under stressful environmental conditions.

Summary

Plant cells fend off herbivores and pathogens and adapt to environmental change through a variety of metabolic processes. One such process involves the mevalonate (MVA) pathway. To better elucidate the details of the MVA pathway in plants, a multi-institutional team of scientists combined a forward genetic screen of Arabidopsis thaliana—a small, flowering plant—with calcium (Ca2+) imaging. Their findings identified the critical role of mevalonate kinase (MVK), a key enzyme in the MVA pathway, in a type of plant metabolic signaling known as purinergic signaling. Specifically, the team found that extracellular Adenosine Triphosphate (eATP) plays a key role because MVK interacts directly with the eATP receptor known as P2K1, and phosphate is thereby transferred to MVK. Finally, when these phosphate sites on MVK are mutated, both the cytoplasmic calcium response and enzymatic activity of MVK are eliminated, and the resistance of this Arabidopsis species to pathogens is depressed.

This study shows that the plasma membrane around P2K1 receptors has a direct impact on plant cellular metabolism through the transfer of phosphate from eATP to MVK, emphasizing the vital role of signaling by purine molecules such as ATP in plants. This work adds to the growing body of knowledge about the importance of eATP signaling in plants because it demonstrates how P2K1 alters plant metabolism by regulating MVK.

Metabolic analysis was performed at the Environmental Molecular Sciences Laboratory (EMSL), a Department of Energy Office of Science, Biological and Environmental Research program user facility.

Contacts

Gary Stacey, University of Missouri staceyg@missouri.edu

Ljiljana Paša-Tolić, Environmental Molecular Sciences Laboratory ljiljana.pasatolic@pnnl.gov

Funding

This research was supported by the following:

National Institutes of Health, National Institute of General Medical Sciences grant
Next-Generation BioGreen 21 Program Systems and Synthetic Agrobiotech Center, Rural Development Administration, Republic of Korea grant
ERA-NET for Coordinating Action in Plant Sciences, U.S. National Science Foundation grant

Publication

S.H. Cho, et al., "Activation of the plant mevalonate pathway by extracellular ATP." Nature Communications 13, 450 (2022). [DOI: 10.1038/s41467-022-28150-w]