Interallelic complementation at the Arabidopsis CRE1 locus uncovers independent pathways for the proliferation of vascular initials and canonical cytokinin signalling

Authors

  • Berenice García-Ponce De León,

    1. Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de la Universidad Autónoma de Madrid Cantoblanco, 28049 Madrid, Spain, and
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  • Jose Manuel Franco Zorrilla,

    1. Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de la Universidad Autónoma de Madrid Cantoblanco, 28049 Madrid, Spain, and
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  • Vicente Rubio,

    1. Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de la Universidad Autónoma de Madrid Cantoblanco, 28049 Madrid, Spain, and
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  • Preeti Dahiya,

    1. Department of Cell and Developmental Biology, John Innes Center, Colney lane, Norwich NR4 7UH, UK
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  • Javier Paz-Ares,

    1. Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de la Universidad Autónoma de Madrid Cantoblanco, 28049 Madrid, Spain, and
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  • Antonio Leyva

    Corresponding author
    1. Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de la Universidad Autónoma de Madrid Cantoblanco, 28049 Madrid, Spain, and
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For correspondence (fax +34 91 585 45 06; e-mail aleyva@cnb.uam.es).
Current address: Instituto de Biotecnología, UNAM. Av Universidad 2001, Col. Chamilpa 62210, Cuernavaca Morelos, México.
Current address: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8104, USA.

Summary

The differentiation of vascular tissue plays a central role in root architecture and its functionality. Regardless of its importance, the molecular mechanisms involved in the inception of vascular morphogenesis and their interaction with hormones are only now beginning to be understood. The characterisation of the WOODEN LEG (wol/cre1 mutant), impaired in procambial cell proliferation and the identification of WOL/CRE1 as a cytokinin receptor, provided the first genetic evidence pointing to a role of cytokinins in the formation of vascular initials. However, the striking wol phenotype in vascular differentiation is unique among all the available cre1 alleles collection. In this work, we identified a mutant with identical deficiencies in vascular differentiation as wol. Complementation analysis revealed that this mutant rescued the wol short-root phenotype. However, genetic characterisation of the mutant showed that the mutation was located at the CRE1 locus, indicating that both alleles displayed interallelic complementation. Trans-heterozygotes characterisation showed that these plants fully restored the deficiency in vascular differentiation but not the canonical cytokinin signalling. Furthermore, we show that, as measured in root growth inhibition, calli regeneration assays and northern analysis, the original wol allele is in fact more sensitive to cytokinins than the trans-heterozygous plants, or some cre1 alleles showing wild-type vascular morphogenesis. Thus, there is no strict correlation between the phenotype in vascular differentiation displayed by the cre1/wol alleles and canonical cytokinin signalling. These results indicate that at least partially independent regulatory circuits may operate in procambial cell proliferation and in cytokinin responsiveness exerted through the CRE1 receptor.

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