Functional diversity of specialized vesicles derived from the endoplasmic reticulum in plants

Purdue University, West Lafayette IN

Investigators

Abstract

Protein trafficking between subcellular compartments is an essential and basic process of cellular life. Plants contain various types of functionally specialized vesicles that accumulate or transport specific proteins important for plant growth, development, and stress responses. In Brassica plants (plants in the cabbage and mustard family), there are specialized vesicles called endoplasmic reticulum (ER) bodies that can generate toxic compounds upon tissue damage as a “mustard oil bomb” against pathogens and herbivores. ER bodies and their associated chemical arsenal were thought to occur only in Brassica plants, but recent studies have shown that ER body-related vesicles are present in all plants. The functions of these vesicles are unknown. This project seeks to understand these ER body-related vesicles and how they contribute to the diversity of biological functions in plants. The Broader Impacts of this project include teaching and training students to conduct their own mini-research projects and the PI will also participate as a mentor for high school science fairs. Vesicle-mediated protein trafficking between subcellular compartments is a basic process of cellular life. Plants contain various types of functionally specialized, ER-derived vesicles (ERDVs) that accumulate or transport specific proteins important for plant growth, development, and stress pathways. In the highly conserved secretory pathway, ER-synthesized proteins fold and pass onto the Golgi apparatus through COPII-coated vesicles before transport to other subcellular compartments. However, in plant cells, some specific ER-synthesized proteins pass into specialized ERDVs and are transported to other compartments in a Golgi-independent manner. ER bodies in Brassica plants are specialized ERDVs that generate toxic chemicals against herbivores and pathogens. These ER bodies are found only in Brassica plants and their origins are unknown. NAI2 is an ER body protein with homologs only in Brassica and is required for ER body formation. Three related NAI2-interacting proteins (NAIP1 to 3) from Arabidopsis are also required for ER body formation but have homologs in all plants. While NAIP1 is specifically associated with ER bodies, NAIP2 and 3 are also associated with related ERDVs containing other proteins. Thus, there is a novel family of ER body-related, NAIP-containing vesicles in all plants. The goal of this project is to establish the functional diversity of the NAIP vesicles by identifying their cargo proteins, determining the regulatory roles of NAIP vesicles, and analyzing additional factors important for the biogenesis of NAIP vesicles. Progress of this project will enhance the understanding of the molecular basis of plant traits such as seed germination, vascular development, and plant defense, which has a multitude of applications, including those in the agricultural setting. 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.