Cytokinins
A cytokinin is a plant hormone that, in combination with auxin, stimulates cell division in plants and determines the course of differentiation. Substances that have these properties are widespread both in bacteria and in eukaryotes. In vascular plants,most cytokinins seem to be produced in the roots and transported from there throughout the rest of the plant. Cytokinins seem to be necessary for mitosis and cell division to take place. They apparently work by influencing the synthesis or activation of proteins that are specifically required for mitosis.
The naturally occurring cytokinins all appear to be derivatives of the purine base, adenine. In contrast to auxins, cytokinins promote the growth of lateral branches. Similarly, auxins promote the formation of lateral roots, whereas cytokinins inhibit it. As a consequence of these relationships, the balance between cytokinins and auxin determines, along with other factors, the appearance of a mature plant,
แหล่งข้อมูล: Understanding Biology. Page 727.
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