In situ analysis of lignins in transgenic tobacco reveals a differential impact of individual transformations on the spatial patterns of lignin deposition at the cellular and subcellular levels

Authors

  • Matthieu Chabannes,

    1. UMR CNRS/UPS 5546, Signaux et Messages Cellulaires chez les Végétaux, Pôle de Biotechnologie Végétale, 24 Chemin de Borde-Rouge – BP 17 Auzeville – 31326 Castanet-Tolosan, France,
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    • These authors contributed equally to this work.

  • Katia Ruel,

    1. UMR CNRS/UPS 5546, Signaux et Messages Cellulaires chez les Végétaux, Pôle de Biotechnologie Végétale, 24 Chemin de Borde-Rouge – BP 17 Auzeville – 31326 Castanet-Tolosan, France,
    2. Centre de Recherches sur les Macromolécules Végétales, CNRS, BP 53, 38041 Grenoble Cedex 09, France,
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  • Arata Yoshinaga,

    1. Laboratory of Structure of Plant Cells, Division of Forest and Biomaterials Science, Kyoto University, Kyoto 606–8502 Japan,
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    • These authors contributed equally to this work.

  • Brigitte Chabbert,

    1. Laboratoire de Biochimie, INRA centre de Reims, 2 Esplanade R. Garros, BP 224, 51686 Reims cedex 2, France, and
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  • Alain Jauneau,

    1. Institut Fédératif de Recherche Fr40 ‘Signalisation Cellulaire et Biotechnologie végétale’, Pôle de Biotechnologie végétale, BP 27, 31326 Castanet Tolosan cedex, France
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  • Jean-Paul Joseleau,

    1. Centre de Recherches sur les Macromolécules Végétales, CNRS, BP 53, 38041 Grenoble Cedex 09, France,
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  • Alain-Michel Boudet

    Corresponding author
    1. UMR CNRS/UPS 5546, Signaux et Messages Cellulaires chez les Végétaux, Pôle de Biotechnologie Végétale, 24 Chemin de Borde-Rouge – BP 17 Auzeville – 31326 Castanet-Tolosan, France,
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For correspondence: (fax +33 (0)5 62 19 35 02; e-mail amboudet@smcv.ups-tlse.fr).

Summary

Using tobacco transgenic lines altered in the monolignol biosynthetic pathway and which differ in their lignin profiles we have evaluated lignin deposition at the cellular and subcellular levels using several microanalytical techniques. Surprisingly, whereas a Cinnamoyl CoA reductase (CCR) down-regulated line with a strong decrease in lignin content exhibited an overall reduction in lignin deposition in the walls of the different xylem cell types, this reduction was selectively targeted to the fibers in a double transformant (down-regulated for both CCR and Cinnamyl alcohol dehydrogenase (CAD)) displaying a similar degree of global lignin content decrease. Fiber and vessel secondary walls of the transgenic tobacco line homozygous for the ccr antisense gene (CCR.H) down-regulated plants were dramatically destructured, particularly in the S2 sublayer, whereas the deposition of lignins in the S1 sublayer was not significantly modified. In contrast, cell wall organization was slightly altered in xylem cells of the double transformant. The relative distribution of non-condensed and condensed units in lignin, evaluated microscopically with specific antibodies, was differentially affected in the transgenics studied and, in a general way, a drop in non-condensed lignin units (β− 0–4 interunit linkages) was associated with a loss of cohesion and extensive disorganization of the secondary wall. These results demonstrate that lignification is tightly and independently regulated in individual cell types and cell wall sublayers. They also show that down-regulation of specific genes may induce targeted changes in lignin structure and in spatial deposition patterns of the polymer.

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