cytokinin (kinin) Any of a group of plant growth substances chemically related to the purine adenine. Cytokinins are involved in numerous aspects of plant metabolism. They stimulate cell division in the presence of auxin and have also been found to delay senescence, overcome apical dominance, and promote cell expansion. They are produced by growing roots in spring and translocated to the stem to stimulate growth of buds. The endosperm of seeds contains high concentrations of cytokinins, which are thought to be involved in development of the embryo. Zeatin is a naturally occurring cytokinin. Carefully formulated mixtures of cytokinins and auxins are used in micropropagation to generate cloned plantlets from undifferentiated callus tissue.

cytokinin (kinetin or kinin) Any of a group of plant hormones that stimulate cell division. Cytokinins work in conjunction with auxins to promote swelling and division in the plant cells producing lateral buds. They can also slow down the aging process in plants, encourage seeds to germinate and plants to flower, and are involved in plant responses to drought and water-logging. They are used commercially to produce seedless grapes, to stimulate germination of barley in brewing, and to prolong the life of green-leaf vegetables.

cytokinin One of a group of plant hormones, including kinetin, that act synergistically with auxins to promote cell division but, unlike auxins, promote lateral growth.

kinetin (6-fururylaminopurine) A degradation product of animal DNA, which does not occur naturally and which has properties similar to those of cytokinins. Applied to certain leaves, kinetin delays senescence in its vicinity and attracts nutrients.