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Hormones213-page9 - when the seeds normally require light...

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Plant Growth Regulators - 9 Cytokinins and Gene Activity Cytokinins are the signal molecules for a receptor (AKH) that activates a protein kinase transduction pathway that ultimately phosphorylates a transcription factor that binds to the promoter region of over 20 different cytokinin response genes. Cytokinin Functions As stated, cytokinins promote cytokinesis, so their location in root meristems, embryos and fruits is not surprising. Cytokinins migrate from roots to the shoot systems of plants in xylem tissue. Cytokinins can promote germination in some seeds in the absence of light,
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Unformatted text preview: when the seeds normally require light for germination • The effects of cytokinins are often studied in tissue culture. Normally, cytokinins work in conjunction with auxins, which promote elongation and cell expansion. When auxin is added to a tissue culture medium, cells in the absence of cytokinins enlarge, but division does not take place. When kinetin and IAA are both added to a tissue culture medium, cells divide rapidly producing many small cells. The ratio of cytokinins to auxin controls what tissues differentiate in the tissue culture....
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