Plants serve as crucial food sources for humans and animals, and they provide non-food products such as medicines, biofuel, wood, and textiles. Thus, improving crop production is important both for enhancing the national economy and for stabilizing food security. However, plant pathogens greatly reduce crop yields, negatively impacting these important goals. Similar to humans and animals, plants have effective mechanisms to protect themselves against pathogens; but if a plant host is unable to induce proper defenses, a pathogen may invade and colonize the host. For a plant to manifest a fully active defense response against invading pathogens, cells need to ensure that proteins with defense functions are trafficked to their correct subcellular location. If such proteins enter an erroneous vesicular trafficking route, they will be delivered to the incorrect subcellular compartment, resulting in proteins that cannot perform their cellular job to detect and induce defense responses.

This project focused on a set of proteins termed vesicular trafficking components that help other proteins with defense roles (called defense cargo) to travel to their cellular location at which they function. This study has uncovered novel physiological roles for two vesicular trafficking components -by functioning either alone or together- to help traffic various defense cargo proteins to and from the plasma membrane (PM). The PM is the cell surface membrane that provides the external boundary of a plant cell, and many proteins with critical roles in plant defense reside in the PM. This study advanced the limited understanding that proteins with roles during early or later stages of pathogen infection need to be at the PM in the correct abundance to detect invading bacterial pathogens and/or induce appropriate cellular defense responses. Using the Goldilocks principle, the levels of defense proteins in the PM must be just right as this project showed that too little defense proteins in the PM prevented plants to induce sufficient immune responses, making a plant more vulnerable to infection by bacterial pathogen. But too much of certain defense cargo proteins in the PM led to heightened or uncontrolled defense responses, which in turn contributed to decreased biomass production. In addition, this project discovered previously unknown cellular roles of these vesicular trafficking components beyond plant defense, including in plant growth and development by modulating the abundance of hormone transporters in the PM.

Overall, discoveries made by this project have provided new insights that in the longer term will lead to novel strategies to enhance plant resistance against pathogen infections and improve other plant responses for increased yield and food security in the US and around the world.

In addition to its biological importance, this project has provided multi-disciplinary training to better prepare three PhD students and one postdoctoral fellow to become successful members of the national scientific work force. In addition, more than 10 first-year undergraduate students have received interdisciplinary research training in plant biology to improve their scientific understanding and literacy by learning to design and perform experiments, analyze data, draw conclusions, and communicate their results. This project has also resulted in enhancing the oral and written communication skills as several of these graduate and undergraduates have received regional and (inter)national honors and awards based on their research discoveries and training received through this project.

Last Modified: 12/31/2023
Modified by: Antje Heese