Cytokinins

Cytokinins are one of several categories of Plant Growth Regulators, or PGR .

History
Cytokinins were first discovered in the laboratory by Folke K. Skoog (of Murashige and Skoog), when experimenting upon coconut milk.

Processes
Cytokinins are involved in several plant processes, including cell division, root and shoot morphogenesis and are responsible for the inhibition of sensecence, or plant aging. They are also utilised for signalling, applying the same transport mechanisms as those for purines and nucleosides.

In Plant Tissue Culture
Cytokinins are used in Plant Tissue Culture Growth Media, sometimes in combination with Auxins. Both can be supplemented in the growth substrate, though both occur naturally. When transferring an apical bud, high levels of cytokinins are added to the growth media to overcome apical dominance, whereby the shoot tip biosynthesizes large amounts of auxins.

Types of Cytokinins
There are two types of Cytokinins: Adenine-type Cytokinins and Phenylurea-type Cytokinins.

Adenine-type Cytokinins
The Adenine-type Cytokinins occur naturally in plants, forming in the roots, leaves and stems. Examples of Adenine-type Cytokinins include: Kinetin, Zeatin and 6-Benzylaminopurine.

Phenylurea-type Cytokinins
The Phenylurea-type Cytokinins have not been proven to occur naturally in plants. An example of Phenylurea-type Cytokinins is Thidiazuron, or TDZ.

PhytoTech Products
Kinetin

Zeatin

6-Benzylaminopurine

Thidiazuron