pax1-1 partially suppresses gain-of-function mutations in Arabidopsis AXR3/IAA17.
BACKGROUND
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.


RESULTS
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.


CONCLUSIONS
We propose that PAX1 influences auxin response via its effects on AXR3 expression and that it regulates other Aux/IAAs secondarily.
Tanimoto
Mimi
M
Department of Biology, University of York, Heslington, York, UK. htanimot@uoguelph.ca
Jowett
Jemma
J
Stirnberg
Petra
P
Rouse
Dean
D
Leyser
Ottoline
O
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002874:Chromosome Mapping; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005875:Gibberellins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D036226:Seedlings / Q000254:growth & development; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
C110728:AXR3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D005875:Gibberellins; D007210:Indoleacetic Acids; D009687:Nuclear Proteins; C521044:PAX1 protein, Arabidopsis; D014157:Transcription Factors; C007842:gibberellic acid