@article{oai:nagoya.repo.nii.ac.jp:00007508,
 author = {Tanaka, Mina and Takei, Kentaro and Kojima, Mikiko and Sakakibara, Hitoshi and Mori, Hitoshi and 森, 仁志},
 issue = {6},
 journal = {The Plant Journal},
 month = {Mar},
 note = {In intact plants, the shoot apex grows predominantly and inhibits axillary bud outgrowth. After shoot apex decapitation, axillary bud outgrowth begins. This phenomenon is called apical dominance. Although the involvement of auxin, which represses axillary bud outgrowth, and cytokinin (CK), which promotes axillary bud outgrowth, has been proposed, little is known about the underlying molecular mechanisms. Here, we demonstrate that local CK biosynthesis in the nodal stem is negatively regulated by auxin by controlling expression of the gene pea adenosine phosphate-isopentenyltransferase (PsIPT), which encodes a key enzyme in CK biosynthesis. Before decapitation, PsIPT1 and PsIPT2 transcripts were undetectable; after decapitation, they were markedly induced in the nodal stem along with CK accumulation. PsIPTs expression was repressed by the application of indole-3-acetic acid (IAA). In excised nodal stem, PsIPTs expression and CK levels also increased under IAA-free conditions. Furthermore, β-glucuronidase expression under the control of the PsIPT2 promoter region in transgenic Arabidopsis was repressed by IAA. Our results indicate that, in apical dominance, one role of auxin is to repress local CK biosynthesis in the nodal stem and that, after decapitation, CKs, which are thought to be derived from the roots, are locally biosynthesized in the nodal stem rather than in the roots.},
 pages = {1028--1036},
 title = {Auxin controls local cytokinin biosynthesis in the nodal stem in apical dominance},
 volume = {45},
 year = {2006}
}