Globoid (botany)

Globoid (Botany)

Illustration of crystalloids and globoids in plant cells.

In botany, a globoid is a spherical or nearly spherical structure found within the cells of certain plants. These structures are typically associated with the storage of phosphorus and other minerals in the form of phytin, a salt of phytic acid. Globoids are commonly found in the aleurone layer of seeds, where they play a crucial role in the storage and mobilization of nutrients during seed germination.

Structure and Composition

Globoids are composed primarily of phytin, which is a complex of inositol hexakisphosphate (phytic acid) and various cations such as calcium, magnesium, and potassium. The presence of these cations helps to stabilize the structure of the globoid and facilitates the storage of phosphorus in a form that is not readily soluble, thus preventing its loss from the seed.

Function

The primary function of globoids is to serve as a reserve of phosphorus and other essential minerals. During seed germination, the stored phosphorus is mobilized and utilized for the synthesis of nucleic acids, ATP, and other vital molecules necessary for the growth and development of the seedling. The breakdown of globoids is mediated by the action of phytase enzymes, which hydrolyze phytic acid to release inorganic phosphate and inositol.

Occurrence

Globoids are most commonly found in the seeds of cereals and legumes, where they are located within the protein bodies of the aleurone layer. They can also be found in other plant tissues, such as the endosperm and cotyledons, although they are less prevalent in these areas.

Related Structures

Globoids are often found in association with crystalloids, which are another type of storage structure found in plant cells. Crystalloids are composed of protein and are typically found within the same protein bodies as globoids. The relationship between globoids and crystalloids is not fully understood, but both structures are thought to play complementary roles in nutrient storage and mobilization.

Related Pages

• Phytin
• Aleurone layer
• Phytase
• Seed germination
• Endosperm