Question

How do auxins and cytokinin work together?

Answer 1

Auxin and cytokinin are the plant hormones. Auxin helps in elongation of the stem, phototropism, geotropism and also at various stages of the life process. Cytokinins are involved in cell division and growth.

Complete answer:
The plant hormones are the signalling molecules which are produced in very small quantities by plants. The plant hormones regulate the growth and development in plants like embryo development, stress tolerance, defence, regulation of organ size, reproductive development etc. Some important plant hormones are ABA, auxin, cytokinin, ethylene etc.
The Auxins are important hormones which mediate cell division and root differentiation. Cytokinin helps in RNA synthesis and enhances the activity of protein and enzymes. Auxin and cytokinin are the most important plant hormones whose combination acts as a potent signalling molecule. In case of shoot growth, it is seen that the low level of auxin along with the high level of cytokinin works best for cell division. The activity of the auxin is inhibited by the low cytokinin concentration.
The antagonistic behaviour of auxin and cytokinin is seen in the case of Apical dominance. Auxins promote apical dominance whereas the presence of cytokinin promotes the sprouting of lateral buds.

Thus, we can conclude that the auxins and cytokinin are antagonistic to each other at higher auxin concentration.

Note:
Apical dominance means the main central stem is dominant over the side stems and its own side twigs. Auxins promote the formation of apical buds and inhibit the formation of lateral buds whereas cytokinin promotes the formation of lateral buds.