An oil body is a
lipid
Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...
-containing structure found in plant cells. The term can refer to at least two distinct kinds of structures in different kinds of plants.
In liverworts
Liverwort
Liverworts are a group of non-vascular land plants forming the division Marchantiophyta (). They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry ...
complex oil bodies are structures unique to liverworts that contain
isoprenoid essential oil
An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...
s and are surrounded by a single membrane. The size, shape, color, and number of oil bodies per cell is characteristic of certain species and may be used to identify these.
In vascular plants
Some species of
vascular plants also contain intracellular structures called oil bodies. Vascular plant oil bodies consist mainly of
triacylglycerols surrounded by a layer consisting of
phospholipid
Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
s and the protein
oleosin. These oil bodies occur largely in seeds but also occur in other plant parts, including leaves.
In seeds
Oil bodies are the organelle that has evolved to hold triglycerides in plant cells. They are therefore the principal store of chemical energy in oleaginous seeds. The structure and composition of plant seed oil bodies has been the subject of research from at least as far back as the 1980s, with several papers published in the 80s and 90s. Recent work, using updated techniques, has given a detailed molecular profile of oil bodies. It now seems that proteins out-number lipids on the surface of oil bodies, and that one protein in particular, called oleosin, dominates.
The lipid and protein fractions of oil bodies are remarkable because they maintain a coherent monolayer over a wide temperature and hydration range.
Gallery
Microscopic views of liverwort cells, showing a variety of oil body shapes and arrangements.
File:Nardia scalaris Blattzellen IMG 8353.jpg, '' Nardia scalaris'', a leafy liverwort
File:Ptilidium ciliare laminazellen.jpeg, '' Ptilidium ciliare'', a leafy liverwort
File:Chiloscyphus pallescens zellen.jpeg, ''Chiloscyphus pallescens'', a leafy liverwort
File:Cephalozia connivens flankenblatt.jpeg, ''Cephalozia connivens'', a leafy liverwort which lacks oil bodies
File:Metzgeria furcata lamina.jpeg, '' Metzgeria furcata'', a thallose liverwort
References
Liverworts
Plant anatomy
Cell anatomy
{{Bryophyte-stub