Among the auxin-type hormone regulators used in in vitro culture, we find Indole Butyric Acid (IBA), Indole Acetic Acid (IAA), Naphthalem Acetic Acid (NAA), 2,4-D amine. In addition to Auxins we also have other hormone regulators such as Cytokinins responsible for stimulating cell division in non-meristematic tissues.
▶ Initially they were called quinines, however due to the internal use of the name for a group of compounds for animal physiology, the term cytokinin (cytokinesis or cell division) was adapted. They are produced in growth zones such as meristems in root tips. The highest concentrations of cytokinins are found in embryos and young developing fruits.
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Cytokinin is also formed in roots and translocated through the xylem to the shoot. However, when the compounds are found in leaves they are completely immobile. Among the cytokinin-type hormone regulators used in in vitro culture, we have Zeatin (Zea), Kinetin (Kin), Benzyl amino purine (BAP), and Adenine Sulfate (SA).
Other hormones are gibberellins whose main effect is to stimulate the longitudinal growth of the stem. Dwarfism is probably an alteration that prevents the formation of gibberellins, for which reason the application of these substances to dwarf plants corrects this defect.
Gibberellins stimulate stem elongation in certain biennial plants that remain in the rosette stage during the first year; they also stimulate flowering in these plants.
Climatic factors (temperature, light, among others) condition flowering by acting on plants and modifying the formation and distribution of gibberellins. Other effects of gibberellins are formation of parthenocarpic fruits, induction of premature flowering, interruption of dormancy of certain tubers and some seeds.
NOTE: Reference material.