Callus (cell biology)

[1] The culture medium is supplemented with plant growth regulators, such as auxin, cytokinin, and gibberellin, to initiate callus formation or somatic embryogenesis.

Callus induction medium consists of agar and a mixture of macronutrients and micronutrients for the given cell type.

The cells that give rise to callus and somatic embryos usually undergo rapid division or are partially undifferentiated such as meristematic tissue.

In alfalfa (Medicago truncatula), however, callus and somatic embryos are derived from mesophyll cells that undergo dedifferentiation.

The callus tissue then undergoes further cell growth and differentiation, forming the respective organ primordia.

Specific auxin-to-cytokinin ratios in plant tissue culture medium give rise to an unorganized growing and dividing mass of callus cells.

[clarification needed] Nevertheless, callus cells are often considered similar enough for standard scientific analysis to be performed as if on a single subject.

For example, using explants composed of low totipotency cells may prolong the time necessary to obtain callus of sufficient size, increasing the total length of the experiment.

[23][24] Henri-Louis Duhamel du Monceau investigated wound-healing responses in elm trees, and was the first to report formation of callus on live plants.

[27] P. White induced callus derived from tumor-developing procambial tissues of hybrid Nicotiana glauca that did not require hormone supplementation.