New Insights Into the Role of Seed Oil Body Proteins in Metabolism and Plant Development

Abstract

Oil bodies (OBs) are ubiquitous dynamic organelles found in plant seeds. They have attracted increasing attention recently because of their important roles in plant physiology. First, the neutral lipids stored within these organelles serve as an initial, essential source of energy and carbon for seed germination and post-germinative growth of the seedlings. Secondly, they are involved in many other cellular processes such as stress responses, lipid metabolism, organ development, and hormone signaling. The biological functions of seed OBs are dependent on structural proteins, principally oleosins, caleosins, and steroleosins, which are embedded in the OB phospholipid monolayer. Oleosin and caleosin proteins are specific to plants and mainly act as OB structural proteins and are important for the biogenesis, stability, and dynamics of the organelle; whereas steroleosin proteins are also present in mammals and play an important role in steroid hormone metabolism and signaling. Significant progress using new genetic, biochemical, and imaging technologies has uncovered the roles of these proteins. Here, we review recent work on the structural or metabolic roles of these proteins in OB biogenesis, stabilization and degradation, lipid homeostasis and mobilization, hormone signal transduction, stress defenses, and various aspects of plant growth and development.

OsClo5 functions as a transcriptional co‐repressor by interacting with OsDi19‐5 to negatively affect salt stress tolerance in rice seedlings

“…Caleosins have been demonstrated to play critical roles in many cellular and biological processes that are coupled closely to synthesis during the mature stage or degradation of storage lipids during seed germination, lipid trafficking/turnover and structural stabilization of LDs in plants (Poxleitner et al ., 2006; Huang, 2018; Shao et al ., 2019). An endoplasmic reticulum (ER)‐localized caleosin and an LDs‐localized caleosin have been identified in the embryos of Brassica napus (Hernandez‐Pinzon et al ., 1999).…”

High oil accumulation in tuber of yellow nutsedge compared to purple nutsedge is associated with more abundant expression of genes involved in fatty acid synthesis and triacylglycerol storage

“…Oil body proteins have been shown to maintain oil body integrity and protect TAG from coalescence and degradation [ 53 , 74 ], emphasizing the importance of TAG packaging/stability in oil bodies, which was thought to be rate limiting and a key determinant for oil accumulation [ 76 , 77 ]. An increasing body of evidence have indicated that oil accumulation appeared to be tightly associated with the expression levels of TAG storage genes, particularly OBO genes.…”

Identification of Functional Noncoding RNA-encoded Proteins on Lipid Droplets

“…For instance, LD resident protein in plants, oleosin, is proposed to comprise an N-terminal amphipathic domain, a central hydrophobic domain, and a C-terminal amphipathic a-helical domain. The central domain anchors oleosin into the hydrophobic core of LD and N- and C-terminal domains are proposed to reside on the monolayer phospholipid membrane of LDs(35, 36). Using bioinformatic tools, we analyzed the possible secondary structure of LDAMP1 (Supplemental Information).…”