Leucoplasts ("formed, molded") are a category of

plastid A plastid is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. Plastids are considered to be intracellular endosymbiotic cyanobacteria. Examples of plastids include chloroplasts ...

and as such are

organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as Organ (anatomy), organs are to th ...

s found in

plant cell Plant cells are the cells present in Viridiplantae, green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids ...

s. They are non-pigmented, in contrast to other plastids such as the chloroplast.

Background

Lacking

photosynthetic pigment A photosynthetic pigment (accessory pigment; chloroplast pigment; antenna pigment) is a pigment that is present in chloroplasts or photosynthetic bacteria and captures the light energy necessary for photosynthesis. List of photosynthetic pigmen ...

s, leucoplasts are located in non-photosynthetic tissues of plants, such as

root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often bel ...

bulbs In botany, a bulb is a short underground stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs during ...

and

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

s. They may be specialized for bulk storage of

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diet ...

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 ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

and are then known as

amyloplast Amyloplasts are a type of plastid, double-enveloped organelles in plant cells that are involved in various biological pathways. Amyloplasts are specifically a type of leucoplast, a subcategory for colorless, non-pigment-containing plastids. Amylo ...

elaioplast Elaioplasts are one of the three possible forms of leucoplasts, sometimes broadly referred to as such. The main function of elaioplasts is synthesis and storage of fatty acids, terpenes, and other lipids, and they can be found in the embryonic ...

s, or

proteinoplast Proteinoplasts (sometimes called ''proteoplasts'', ''aleuroplasts'', and ''aleuronaplasts'') are specialized organelles found only in plant cells. Proteinoplasts belong to a broad category of organelles known as plastids. Plastids are specialize ...

s (also called aleuroplasts) respectively. However, in many cell types, leucoplasts do not have a major storage function and are present to provide a wide range of essential biosynthetic functions, including the synthesis of fatty acids such as

palmitic acid Palmitic acid (hexadecanoic acid in IUPAC nomenclature) is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms.Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra. The ...

, many amino acids, and tetrapyrrole compounds such as

heme Heme (American English), or haem (Commonwealth English, both pronounced /Help:IPA/English, hi:m/ ), is a ring-shaped iron-containing molecule that commonly serves as a Ligand (biochemistry), ligand of various proteins, more notably as a Prostheti ...

. In general, leucoplasts are much smaller than

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s and have a variable morphology, often described as amoeboid. Extensive networks of

stromule A stromule is a microscopic structure found in plant cells. Stromules ( stroma-filled tubules) are highly dynamic structures extending from the surface of all plastid types, including proplastids, chloroplasts, etioplasts, leucoplasts, amyloplast ...

s interconnecting leucoplasts have been observed in epidermal cells of

hypocotyl The hypocotyl (short for "hypocotyledonous stem", meaning "below seed leaf") is the stem of a germinating seedling, found below the cotyledons (seed leaves) and above the radicle (root). Eudicots As the plant embryo grows at germination, it send ...

s, and

petal Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corol ...

s, and in

callus A callus (: calluses) is an area of thickened and sometimes hardened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, b ...

and suspension culture cells of tobacco. In some cell types at certain stages of development, leucoplasts are clustered around the

nucleus Nucleus (: nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucleu ...

with stromules extending to the cell periphery, as observed for proplastids in the root meristem.

Etioplasts

Pre-granal etioplasts, which are

s that have not matured but can be chloroplasts deprived of light, lack the active pigment. They can thereby can be considered leucoplasts. After several minutes exposure to light, etioplasts transform into functioning chloroplasts and cease being leucoplasts. Amyloplasts are of large size and store starch.

Proteinoplast Proteinoplasts (sometimes called ''proteoplasts'', ''aleuroplasts'', and ''aleuronaplasts'') are specialized organelles found only in plant cells. Proteinoplasts belong to a broad category of organelles known as plastids. Plastids are specialize ...

s store proteins and are found in seeds (pulses), while elaioplasts store fats and oils and are found in seeds. They are also called oleosomes.

External links

* {{Self-replicating organic structures Organelles Plant cells Plant physiology

Background

Etioplasts

See also

External links