Tanimoto Mimi, Jowett Jemma, Stirnberg Petra, Rouse Dean, Leyser Ottoline
Department of Biology, University of York, Heslington, York, UK.
BMC Plant Biol. 2007 Apr 12;7:20. doi: 10.1186/1471-2229-7-20.
The plant hormone auxin exerts many of its effects on growth and development by controlling transcription of downstream genes. The Arabidopsis gene AXR3/IAA17 encodes a member of the Aux/IAA family of auxin responsive transcriptional repressors. Semi-dominant mutations in AXR3 result in an increased amplitude of auxin responses due to hyperstabilisation of the encoded protein. The aim of this study was to identify novel genes involved in auxin signal transduction by screening for second site mutations that modify the axr3-1 gain-of-function phenotype.
We present the isolation of the partial suppressor of axr3-1 (pax1-1) mutant, which partially suppresses almost every aspect of the axr3-1 phenotype, and that of the weaker axr3-3 allele. axr3-1 protein turnover does not appear to be altered by pax1-1. However, expression of an AXR3::GUS reporter is reduced in a pax1-1 background, suggesting that PAX1 positively regulates AXR3 transcription. The pax1-1 mutation also affects the phenotypes conferred by stabilising mutations in other Aux/IAA proteins; however, the interactions are more complex than with axr3-1.
We propose that PAX1 influences auxin response via its effects on AXR3 expression and that it regulates other Aux/IAAs secondarily.
植物激素生长素通过控制下游基因的转录对生长和发育发挥多种作用。拟南芥基因AXR3/IAA17编码生长素响应转录抑制因子Aux/IAA家族的一个成员。AXR3中的半显性突变由于编码蛋白的超稳定化导致生长素反应幅度增加。本研究的目的是通过筛选修饰axr3-1功能获得型表型的第二位点突变来鉴定参与生长素信号转导的新基因。
我们展示了axr3-1（pax1-1）突变体部分抑制子的分离，该抑制子部分抑制了axr3-1表型的几乎每个方面，以及较弱的axr3-3等位基因的表型。pax1-1似乎未改变axr3-1蛋白的周转。然而，在pax1-1背景下，AXR3::GUS报告基因的表达降低，表明PAX1正向调节AXR3转录。pax1-1突变也影响由其他Aux/IAA蛋白的稳定化突变赋予的表型；然而，相互作用比与axr3-1的情况更复杂。
我们提出PAX1通过其对AXR3表达的影响来影响生长素反应，并且它其次调节其他Aux/IAA蛋白。
