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Cytokinins participate in local and long-distance signalling, with the same transport mechanism as purines and nucleosides. [5] Typically, cytokinins are transported in the xylem. [2] Cytokinins act in concert with auxin, another plant growth hormone. The two are complementary, [6] [7] having generally opposite effects. [2]
Auxin also stimulates cell division if cytokinins are present. 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 ...
Cytokinins and auxins often work together, and the ratios of these two groups of plant hormones affect most major growth periods during a plant's lifetime. Cytokinins counter the apical dominance induced by auxins; in conjunction with ethylene, they promote abscission of leaves, flower parts, and fruits.
Some fruit trees have strong apical dominance, and young trees can become "leggy", with poor side limb development. Apical dominance can be reduced in this case, or in cases where limbs are broken off by accident, by cutting off the auxin flow above side buds that one wishes to stimulate. This is often done by orchardists for young trees.
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 ...
Cytokinins participate in short and long-distance signaling and are transported for this signaling through the xylem of plants. [3] Cytokinins control the differentiation of meristem cells in plant development, particularly in shoots and roots where plants undergo growth. [4]
Indole-3-acetic acid (IAA, 3-IAA) is the most common naturally occurring plant hormone of the auxin class. It is the best known of the auxins, and has been the subject of extensive studies by plant physiologists. [1] IAA is a derivative of indole, containing a carboxymethyl substituent. It is a colorless solid that is soluble in polar organic ...
Within the 20-year timespan, many scientists have actively contributed to examining and reevaluating Hager's acid-growth hypothesis. Despite the accumulation of observations that evidently identify the final target of the auxin-induced action to be H +-ATPase, which excretes H + protons to the apoplast and take in K + ions through its rectifying K + channel in the following years, the ...