Cytokinins are a major class of plant hormones that are involved
in various aspects of plant development, ranging from organ
formation and apical dominance to leaf senescence. Cytokinin
and auxin have long been known to interact antagonistically,
and more recent studies have shown that cytokinins also interact
with other plant hormones to regulate plant development. A
growing body of research has begun to elucidate the molecular
and genetic underpinnings of this extensive crosstalk. The rich
interconnections between the synthesis, perception and
transport networks of these plant hormones provide a wide
range of opportunities for them to modulate, amplify or buffer
one another. Here, we review this exciting and rapidly growing
area of cytokinin research.