Kim Hoyeun, Park Pil-Joon, Hwang Hyun-Ju, Lee So-Young, Oh Man-Ho, Kim Sang-Gu
Department of Biological Sciences, Seoul National University, Republic of Korea.
Biosci Biotechnol Biochem. 2006 Apr;70(4):768-73. doi: 10.1271/bbb.70.768.
Transgenic plants overexpressing AXR3/IAA17 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 AXR3/IAA17 gene expression in brassinosteroid (BR)-regulated root development. Exogenous epiBL application significantly induced expression of the AXR3/IAA17 gene as well as several Aux/IAA genes, such as AXR2/IAA7, SLR/IAA14, and IAA28. We analyzed the transcription levels of several Aux/IAA genes related to root development in the BR signaling mutant bri1 and the BR biosynthesis mutant det2. AXR3/IAA17 gene expression was significantly decreased in bri1 plants. In det2 plants, expression of AXR3/IAA17 slightly decreased. This in turn suggests that epiBL induced these Aux/IAA genes, and that these induced gene products might function as factors in root development. Furthermore, AXR3/IAA17 might be involved in the BR signaling pathway, suggesting an intersection node of BR-auxin signaling in root development.
过表达AXR3/IAA17的转基因植物根系生长受到损害。具体而言，它们在侧根和根毛发育方面表现出严重缺陷，类似于表油菜素内酯（epiBL）处理的野生型植物的根表型。在此，我们研究了AXR3/IAA17基因表达在油菜素类固醇（BR）调节的根系发育中的作用。外源施加epiBL显著诱导了AXR3/IAA17基因以及几个Aux/IAA基因的表达，如AXR2/IAA7、SLR/IAA14和IAA28。我们分析了BR信号突变体bri1和BR生物合成突变体det2中几个与根系发育相关的Aux/IAA基因的转录水平。AXR3/IAA17基因在bri1植物中的表达显著降低。在det2植物中，AXR3/IAA17的表达略有下降。这进而表明epiBL诱导了这些Aux/IAA基因，并且这些诱导的基因产物可能作为根系发育的因子发挥作用。此外，AXR3/IAA17可能参与BR信号通路，这表明在根系发育中BR-生长素信号存在一个交汇节点。
