Endosperm

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Endosperm

Endosperm is the tissue produced in the seed

Seed

A seed is a small Plant embryogenesis plant enclosed in a covering called the seed coat, usually with some Food storage. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant....
s of most flowering plant

Flowering plant

The flowering plants or angiosperms are the most widespread group of Embryophytes. The flowering plants and the gymnosperms are the only extant groups of Spermatophyte....
s around the time of fertilization. It surrounds the embryo

Embryo

An embryo is a multicellular organism ploidy eukaryote in its earliest stage of development, from the time of first cell division until birth, Egg , or germination....
and provides nutrition in the form of starch

Starch

File:Amylose2.svgFile:Amylopektin Sessel.svgStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds....
, though it can also contain oils and protein

Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
. This makes endosperm an important source of nutrition in human diet. For example, wheat

Wheat

Wheat , is a worldwide cultivated Poaceae from the Levant region of the Middle East. Globally, after maize, wheat is the second most-produced food among the cereal just above rice....
endosperm is ground into flour for bread

Bread

Bread is a staple food prepared by baking a dough of flour and water. It may be leavened or unleavened. Edible salt, fat and a leavening agent such as yeast are common ingredients, though bread may contain a range of other ingredients: milk, Egg , sugar, spice, fruit , vegetables , Nut or seeds ....
(the rest of the grain is included as well in whole wheat flour

Whole wheat flour

Whole wheat flour is a Powder substance derived by grinding or mashing the wheat whole grain. It is used in baking but typically added to other "white" flours to provide nutrients , texture, and body to the finished product....
), while barley

Barley

Barley is an annual plant cereal grain derived from the grass Hordeum vulgare. It serves as a major animal feed crop, with smaller amounts used for malting and in health food, as well as the making of alcoholic beverages beer and whisky....
endosperm is the main source for beer

Beer

Beer is the world's oldest and most widely consumed alcoholic beverage and the third most popular drink overall after water and tea. It is produced by the brewing and Fermentation of starches, mainly derived from cereal?the most common of which is malted barley, although wheat, maize , and rice are widely used....
production.

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Encyclopedia

Endosperm is the tissue produced in the seed

Seed

Flowering plant

Embryo

Starch

Protein

Wheat

Bread

Whole wheat flour

Barley

Beer

Coconut

The Coconut Palm is a member of the Family Arecaceae . It is the only species in the genus Cocos, and is a large palm, growing to 30 m tall, with pinnate leaf 4-6 m long, pinnae 60-90 cm long; old leaves break away cleanly leaving the trunk smooth....
"meat" and "milk", and corn

Corn

Corn may refer to:...
, including popcorn

Popcorn

Popcorn or popping corn is a type of maize, which explodes from the kernel and puffs up when heated. Corn popping was originally discovered by Native Americans in the United States, but became popular as a snack food during the United States Great Depression....
.

Origin of endosperm

Primitive plants have seeds that have small embryos and abundant endosperm, and the evolutionary development of seed plants tends to show a trend towards plants with mature seeds with little or no endosperm. In more modern plants the embryo occupies most of the seed and the endosperm is non developed or consumed before the seed matures.

Double fertilization

Endosperm is formed when the two sperm nuclei

Sperm

The term sperm is derived from the Greek word sperma and refers to the male reproductive Cell . In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell....
inside a pollen

Pollen

Pollen is a fine to coarse powder consisting of Gametophyte , which produce the male gametes of spermatophyta. A hard coat covering the pollen grain protects the sperm cells during the process of their movement between the stamens of the flower to the pistil of the next flower....
grain reach the interior of an embryo sac

Ovule

Ovule literally means "small ovum." In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: The integuments forming its outer layer, the nucellus , and the megaspore-derived female gametophyte in its center....
or female gametophyte. One sperm nucleus fertilizes the egg

Ovum

An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization....
, forming a zygote

Zygote

A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
, while the other sperm nucleus usually fuses with the two polar nuclei at the center of the embryo sac, forming a primary endosperm cell (its nucleus is often called the triple fusion nucleus). This cell created in the process of (double fertilization

Fertilisation

Fertilisation , is the fusion of gametes to produce a new organism. In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo....
) develops into the endosperm. Because it is formed by a separate fertilization, the endosperm constitutes an organism separate from the embryo.

About 70% of angiosperm species have endosperm cells that are polyploids, typically triploid (containing three sets of chromosomes) but can vary widely from diploid (2n) to 15n.

One primitive species of flowering plant, Nuphar polysepala
Nuphar

Nuphar is genus of aquatic plants in the family Nymphaeaceae, with a temperate Northern Hemisphere distribution. The common name, shared with some other genera in the same family, is water lily or waterlily....
, has endosperm that is diploid, resulting from the fusion of a pollen nucleus with one, rather than two, maternal nuclei. It is believed that early in the development of angiosperm linages, there was a duplication in this mode of reproduction, producing seven-celled/eight-nucleate female gametophytes, and triploid endosperms with a 2:1 maternal to paternal genome ratio.

Endosperm formation

There are two different types of endosperm formation, the nuclear (or liquid endosperm) type, where formation of cell wall is delayed for a number of cell divisions, and the cellular, where cell wall formation is initiated as the nuclei divide. The nuclear type is the most common one in angiosperms. Sweet corn is picked for eating at the tender liquid endosperm stage, before cell walls have formed and the sugars have been converted to starch. The 'milk' of the coconut

Coconut

The role of endosperm in seed development

In some groups (e.g. grains of the family Poaceae

Poaceae

Poaceae or Gramineae is a family in the Class Liliopsida of the Magnoliophyta. Plants of this family are usually called grasses; the shrub- or tree-like plants in this family are called bamboo ....
) the endosperm persists to the mature seed stage as a storage tissue, in which case the seeds are called "albuminous" or "endospermous", and in others it is absorbed during embryo development (e.g., most members of the family Fabaceae

Fabaceae

Fabaceae or Leguminosae is a large and economically important family of flowering plants, which is commonly known as the legume family, pea family, bean family or pulse family....
, including the common bean

Common bean

The common bean, Phaseolus vulgaris, is an herbaceous annual plant domesticated independently in ancient Mesoamerica and the Andes, and now grown worldwide for its edible bean, popular both dry and as a green bean....
, Phaseolus vulgaris), in which case the seeds are called "exalbuminous" or "cotyledonous" and the function of storage tissue is performed by enlarged cotyledons ("seed leaves"). In certain species (e.g. corn, Zea mays); the storage function is distributed between both endosperm and the embryo. Some mature endosperm tissues store fats (e.g. castor bean, Ricinis communis) and others (including grains, such as wheat and corn) store mainly starches. The dust-like seeds of orchids have no endosperm. Orchid seedlings are mycoheterotrophic in their early development. In some other species, such as coffee

Coffee

Coffee is a brewed drink prepared from roasted seeds, commonly called coffee beans, of the Coffea. Caffeinated coffee has a stimulating effect in humans....
, the endosperm also does not develop. Instead the nucellus produces a nutritive tissue termed "perisperm". The endosperm of some species is responsible for seed dormancy. Endosperm also mediates the transfer of nutrients from the mother plant to the embryo, it acts as a location for gene imprinting, and is responsible for aborting seeds produced from genetically mismatched parents. In angiosperms, the endosperm contain hormones such as cytokinin

Cytokinin

Cytokinins are a class of plant growth substances that promote cell division. They are primarily involved in Cell growth, cellular differentiation, and other physiology processes....
s, which regulate cellular differentiation and embryonic organ formation.

Cereal grains

Cereal

Cereals, or cereal grains, are mostly Poaceae cultivated for their edible brans or fruit seeds . Cereal grains are grown in greater quantities and provide more energy worldwide than any other type of crop; they are therefore staple foods....
crops are grown for their palatable fruit

Fruit

The term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. In botany, which is the scientific study of plants, fruits are the ripened Ovary of flowering plants....
(grains

Cereal

Caryopsis

In botany, a caryopsis is a type of simple dry fruit — one that is monocarpelate and indehiscent and resembles an achene, except that in a caryopsis the pericarp is fused with the thin seed #Seed_structure....
), which are primarily endosperm. In the caryopsis, the thin fruit wall is fused to the seed coat. Therefore, the nutritious part of the grain is the seed and its endosperm. In some cases (e.g. wheat, rice) the endosperm is selectively retained in food processing (as in white flour), and the embryo and seed coat removed. Endosperm thus has an important role within the human diet, worldwide.

The aleurone

Aleurone

Aleurone is a protein found in protein granules of maturing seeds and tubers. The term is also used for the outermost cell layer of the seed coat, the aleurone layer....
is a maternal tissue that is retained as part of the seed in many small grains. The aleurone functions for both storage and digestion. During germination it secretes the amylase

Amylase

Amylase is an enzyme that breaks starch down into sugar. Amylase is present in human saliva, where it begins the chemical process of digestion....
enzyme that breaks down endosperm starch into sugars to nourish the growing seedling.