The plastidial MEP-pathway signature in mitochondrial structure and function

Mitochondria are known as the ‘power-house’ in both animal and plant cells. In plant cells, mitochondria are the site of respiration where fuel derived from photosynthesis in the chloroplasts is converted to energy currency. Mitochondria can move within the cell, and upon encountering each other undergo fusion, resulting in the merger of two mitochondria into a single larger mitochondrion.

Conversely, a single mitochondrion can divide into two distinct mitochondria via fission. The balanced frequencies of fusion and fission determine the overall morphology of the mitochondrial population, and are crucial for maintaining mitochondrial functions such as respiratory capacity and response to stress signals. This project will use genetic manipulations of a biochemical route (the “MEP pathway”) used to respond to stress, in order to uncover how alteration of a chloroplast’s metabolism affects the genes and proteins that determine the shape and activity of mitochondria.

The outcome of this research will determine the potential signaling functions of chloroplasts through the MEP-pathway and determine if chloroplasts affect mitochondria directly, or if the signal must first travel through the cell nucleus in order to remodel mitochondrial shape and function. These results could be used to help plants become more resistant to parasites, and tolerant of growth in dry or other stressful areas.

This project will also provide laboratory training for undergraduate and graduate students as well as postdoctoral fellows; and will expose high school students to the study of plant biochemistry and its importance to the growth of plants and role in food production.

Although both the mevalonic acid pathway and MEP pathway synthesize plant isoprenoids, the MEP pathway is indispensable to plant growth, which suggests that it has other functions. Mutants in the MEP pathway give rise to cells with altered mitochondrial fission and fusion rates leading to altered morphologies. This project will investigate communication between chloroplast and mitochondria via the MEP-pathway through two Aims: A) Alter specific steps of the MEP pathway and examine mitochondrial morphology via biochemistry, genetics, and fluorescent and electron microscope tomography; B) Use physiological, genetic, and transcriptomics techniques to investigate which steps of mitochondrial morphogenesis are perturbed.

This work will provide fundamental insights into the molecular and biochemical links required for functional coordination of two interdependent types of organelles in plants, providing greater understanding of interorganellar communication in all eukaryotic cells as well as understanding of biochemistry of plant resistance to harsh conditions. In addition, the PI will bring local students from five nearby underfunded high schools into the laboratory for yearlong training.

The PI as well as students and postdoctoral fellows in the laboratory will also participate in organizing and judging local science fairs.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.