Cytokinin/auxin control of apical dominance

Although the concept of apical dominance control by the ratio of cytokinin to auxin is not new, recent experimen-tation with transgenic plants has given this concept renew-ed attention. In the present study, it has been demonstrated that cytokinin treatments can partially reverse the inhibi-tory effect of auxin on lateral bud outgrowth in intact shoots of Ipomoea nil. Although less conclusive, this also appeared to occur in buds of isolated nodes. Auxin in-hibited lateral bud outgrowth when applied either to the top of the stump of the decapitated shoot or directly to the bud itself. However, the fact that cytokinin promotive effects on bud outgrowth are known to occur when cyto-kinin is applied directly to the bud suggests different trans-port tissues and/or sites of action for the two hormones. Cytokinin antagonists were shown in some experiments t