Overexpression of EgROP1, a Eucalyptus vascular-expressed Rac-like small GTPase, affects secondary xylem formation in Arabidopsis thaliana

Authors

  • Camille Foucart,

    1. UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F–31326 Castanet Tolosan, France
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  • Alain Jauneau,

    1. IFR 40, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F–31326 Castanet Tolosan, France
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  • Jean-Marc Gion,

    1. UPR39 Génétique Forestière, Cirad-BIOS, Campus de Baillarguet TA 10C, F–34398 Montpellier Cedex 5, France
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  • Nicolas Amelot,

    1. UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F–31326 Castanet Tolosan, France
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  • Yves Martinez,

    1. IFR 40, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F–31326 Castanet Tolosan, France
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  • Patricia Panegos,

    1. UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F–31326 Castanet Tolosan, France
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  • Jacqueline Grima-Pettenati,

    1. UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F–31326 Castanet Tolosan, France
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  • Pierre Sivadon

    1. UMR 5546 CNRS/Université Toulouse III, Pôle de Biotechnologies Végétales, 24 chemin de Borde Rouge, BP 42617 Auzeville, F–31326 Castanet Tolosan, France
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Author for correspondence:
Jacqueline Grima-Pettenati
Tel:+33 562 193 513
Email: grima@scsv.ups-tlse.fr

Summary

  • • To better understand the genetic control of secondary xylem formation in trees we analysed genes expressed during Eucalyptus xylem development.
  • Using eucalyptus xylem cDNA libraries, we identified EgROP1, a member of the plant ROP family of Rho-like GTPases. These signalling proteins are central regulators of many important processes in plants, but information on their role in xylogenesis is scarce.
  • • Quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) confirmed that EgROP1 was preferentially expressed in the cambial zone and differentiating xylem in eucalyptus. Genetic mapping performed in a eucalyptus breeding population established a link between EgROP1 sequence polymorphisms and quantitative trait loci (QTLs) related to lignin profiles and fibre morphology. Overexpression of various forms of EgROP1 in Arabidopsis thaliana altered anisotropic cell growth in transgenic leaves, but most importantly affected vessel element and fibre growth in secondary xylem. Patches of fibre-like cells in the secondary xylem of transgenic plants showed changes in secondary cell wall thickness, lignin and xylan composition.
  • • These results suggest a role for EgROP1 in fibre cell morphology and secondary cell wall formation making it a good candidate gene for marker-based selection of eucalyptus trees.

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