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When cytokinin and auxin are both added together, the cells expand and differentiate. When cytokinin and auxin are present in equal levels, the parenchyma cells form an undifferentiated callus. A higher ratio of cytokinin induces growth of shoot buds, while a higher ratio of auxin induces root formation. [2]
When auxin and cytokinin are applied to callus, rooting can be generated with higher auxin to cytokinin ratios, shoot growth is induced by lower auxin to cytokinin ratios, and a callus is formed with intermediate ratios, with the exact threshold ratios depending on the species and the original tissue. Auxin also induces sugar and mineral ...
Zeatin, a cytokinin Cytokinins (CKs) are a group of chemicals that influence cell division and shoot formation. They also help delay senescence of tissues, are responsible for mediating auxin transport throughout the plant, and affect internodal length and leaf growth.
The shoot tip rising from the SAM inhibits the growth of the lateral bud by repressing auxin. When the shoot is cut off, the lateral bud begins to lengthen which is mediated by a release of cytokinin. Once the apical dominance has been lifted from the plant, elongation and lateral growth is promoted and the lateral buds grow into new branches.
A classical experiment by Folke Skoog and Carlos O. Miller on tobacco pith used as the starting explant shows that the supplementation of culture media by different ratios of auxin to cytokinin concentration induces the formation of roots – with higher auxin to cytokinin ratio, the rooting (rhizogenesis) is induced, applying equal amounts of ...
Kinetin is often used in plant tissue culture to induce callus formation (in conjunction with auxin) and regenerate shoot tissues from callus (with lower auxin concentration). For a long time, it was believed that kinetin was an artifact produced from the deoxyadenosine residues in DNA , which degraded when standing for long periods or when ...
Gradual removal of auxin and cytokinin and introduction of abscisic acid (ABA) will allow an embryo to form. [17] Using somatic embryogenesis has been considered for mass production of vegetatively propagated conifer clones and cryopreservation of germplasm .
For example, an excess of auxin will often result in a proliferation of roots, while an excess of cytokinin may yield shoots. A balance of both auxin and cytokinin will often produce an unorganised growth of cells, or callus, but the morphology of the outgrowth will depend on the plant species as well as the medium composition. As cultures grow ...