The food-storing tissue inside the seed is known as endosperm. Endosperm stores nutrients required for the development of the embryo during seed germination. Nutrients in the endosperm can be consumed as food by humans and animals. It is formed by the triple fusion of the primary endosperm nucleus during double fertilization of angiosperms. A prominent endosperm can be identified in monocot seeds. It mainly consists of starch. Hence, the endosperm is the dibble portion of the seed. Some seeds contain oils in their endosperms. The sugars in the endosperm can be used for beer production.
Key Areas Covered
1. What is Endosperm
– Definition, Structure, Types
2. What is the Function of the Endosperm
– Role of Endosperm
Key Terns: Embryo, Endosperm, Oils, Proteins, Seed Germination, Starch
What is Endosperm
Endosperm is a part of a seed that acts as a food store for the developing embryo of plants. It is formed by the triple fusion of the primary endosperm nucleus during double fertilization. Double fertilization occurs in angiosperms. The resulting nucleus of the triple fusion is generally triploid as it is formed by the fusion of three haploid nuclei together. The fertilized nucleus is divided by mitosis, forming a tissue called endosperm. Endosperm is typically considered as polyploid; this can be varied from 2n to 15n. The fertilized nucleus is divided by mitosis, forming a tissue called endosperm. Starch is mostly found in the endosperm. Some endosperms contain oils and proteins as well.
Monocots contain a prominent endosperm. They are called endospermic seeds. Since the endosperm in dicots is less prominent, their seeds are called non-endospermic seeds. All endosperms can be divided into three based on the mode of development.
- Nuclear type endosperms – Nuclear type endosperms are produced by the free nuclear divisions of primary endosperm nucleus. Ex: Coconut water
- Cellular type endosperm – Cellular type endosperm is formed by the covering of primary endosperm nucleus by a cell wall. Ex: Coconut meat
- Helobial type endosperm – Helobial type endosperm is formed by combining both nuclear type and cellular type endosperms. Ex: Coconut
The endosperm of coconut is shown in figure 1.
Figure 1: Coconut Endosperm
What is the Function of the Endosperm
Endosperm is mainly composed of nutrients such as starch, proteins or oils. These nutrients are used for many purposes.
- During seed germination – The nutrients in the endosperm are used in the development of embryo during germination. During germination, seeds are apart from their mother tree. The seeds do not contain chlorophyll for photosynthesis. Therefore, there isn’t any source of energy available for germination. Hence, plants store nutrients in the seed itself to aid in the development of the embryo.
- As a food – The starch in the cereal crops can be consumed by humans and animals as food. Ex: Whole wheat flour is used in the bakery industry, Barley endosperm is used in the beer production. Nutritional value of wheat kernel is shown in figure 2.
Figure 2: Nutritional Value of Wheat Kernel
Some endosperms such as endosperms in legume seeds store proteins as nutrients. Oils can also be extracted from endosperms such as coconut oil, corn oil, sunflower oil, etc.
Conclusion
Endosperm is a structure of a seed that stores nutrients. Nutrients may be stored in the form of starch, proteins or oils. These nutrients are used by the seed during germination to develop an embryo. In addition, starch, proteins, and oils of the endosperm can be used as food for humans and animals.
Reference:
1. Yan, D, et al. “The Functions of the Endosperm during Seed Germination.” Plant & Cell Physiology., U.S. National Library of Medicine, Sept. 2014, Available here.
Image Courtesy:
1. “Coconut layers” By Kerina yin – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Wheat-kernel nutrition” By Wheat-kernel_nutrition.svg: Jkwchuiderivative work: Jon C (talk) – Wheat-kernel_nutrition.svg (CC BY-SA 3.0) via Commons Wikimedia
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