Brassinosteroid Signals Control Expression of the AXR3/IAA17 Gene in the Cross-Talk Point with Auxin in Root Development
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Transgenic plants overexpressing <I>AXR3/IAA17</I> were impaired in root growth. Specifically, they exhibited severe defects in lateral root and root hair development similar to the root phenotypes of epi-brassinolide (epiBL)-treated wild-type plants. Here, we investigated the involvement of <I>AXR3/IAA17</I> gene expression in brassinosteroid (BR)-regulated root development. Exogenous epiBL application significantly induced expression of the <I>AXR3/IAA17</I> gene as well as several <I>Aux/IAA</I> genes, such as <I>AXR2/IAA7</I>, <I>SLR/IAA14</I>, and <I>IAA28</I>. We analyzed the transcription levels of several <I>Aux/IAA</I> genes related to root development in the BR signaling mutant <I>bri1</I> and the BR biosynthesis mutant <I>det2</I>. <I>AXR3/IAA17</I> gene expression was significantly decreased in <I>bri1</I> plants. In <I>det2</I> plants, expression of <I>AXR3/IAA17</I> slightly decreased. This in turn suggests that epiBL induced these <I>Aux/IAA</I> genes, and that these induced gene products might function as factors in root development. Furthermore, <I>AXR3/IAA17</I> might be involved in the BR signaling pathway, suggesting an intersection node of BR-auxin signaling in root development.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(4), 768-773, 2006-04-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry