Abstract
Apical dominance is a phenomenon in which a terminal bud inhibits the outgrowth of axillary buds. Auxin and cytokinin are thought to have a major role in this process. Based on our previous data we concluded that a role of auxin delivered from terminal bud is to control cytokinin biosynthesis in the stem by repression of isopentenyltransferase (IPT) expression. To elucidate how auxin represses PsIPT expression, we generated transgenic Arabidopsis containing the GUS reporter gene under the control of promoter region of PsIPT2. Because GUS protein seems to be stable in plant cells, we examined GUS transcript levels. GUS was expressed in 10-day-old transgenic Arabidopsis seedlings and was repressed by IAA treatment. The GUS expression pattern was the same as that of PsIPT2 expression in the pea stem. These results indicated that Arabidopsis have molecular mechanisms of repression similar to those of auxin on PsIPT2 expression in pea.
