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The POLARIS gene of Arabidopsis encodes a predicted peptide required for correct root growth and leaf vascular patterning

Casson, S.A.; Chilley, P.; Topping, J.F.; Evans, I.M.; Souter, M.; Lindsey, K.


S.A. Casson

P. Chilley

J.F. Topping

I.M. Evans

M. Souter


The POLARIS (PLS) gene of Arabidopsis was identified as a promoter trap transgenic line, showing -glucuronidase fusion gene expression predominantly in the embryonic and seedling root, with low expression in aerial parts. Cloning of the PLS locus revealed that the promoter trap T-DNA had inserted into a short open reading frame (ORF). Rapid amplification of cDNA ends PCR, RNA gel blot analysis, and RNase protection assays showed that the PLS ORF is located within a short (500 nucleotides) auxin-inducible transcript and encodes a predicted polypeptide of 36 amino acid residues. pls mutants exhibit a short-root phenotype and reduced vascularization of leaves. pls roots are hyperresponsive to exogenous cytokinins and show increased expression of the cytokinin-inducible gene ARR5/IBC6 compared with the wild type. pls seedlings also are less responsive to the growth-inhibitory effects of exogenous auxin and show reduced expression of the auxin-inducible gene IAA1 compared with the wild type. The PLS peptide-encoding region of the cDNA partially complements the pls mutation and requires the PLS ORF ATG for activity, demonstrating the functionality of the peptide-encoding ORF. Ectopic expression of the PLS ORF reduces root growth inhibition by exogenous cytokinins and increases leaf vascularization. We propose that PLS is required for correct auxin-cytokinin homeostasis to modulate root growth and leaf vascular patterning.

Journal Article Type Article
Publication Date Aug 1, 2002
Deposit Date May 17, 2007
Journal Plant Cell
Print ISSN 1040-4651
Electronic ISSN 1532-298X
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 14
Issue 8
Pages 1705-1721
Public URL
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