Impact of different levels of cinnamyl alcohol dehydrogenase down-regulation on lignins of transgenic tobacco plants |
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Authors: | Nabila Yahiaoui Christiane Marque Kathryn E. Myton Jonathan Negrel Alain Michel Boudet |
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Affiliation: | (1) UMR CNRS/UPS 5546, Centre de Biologie et Physiologie Végétales, 118, route de Narbonne, F-31062 Toulouse CEDEX, France, FR;(2) Laboratoire de Phytoparasitologie, INRA-CNRS, INRA BV1540, F-21034 Dijon CEDEX, France, FR |
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Abstract: | The effects of cinnamyl alcohol dehydrogenase (CAD, EC.1.1.1.195) down-regulation on lignin profiles of plants were analysed in four selected transgenic lines of tobacco (Nicotiana tabacum L. cv. Samsun) exhibiting different levels of CAD activity (8–56% of the control). A significant decrease in thioacidolysis yields (i.e. yield of β-O-4 linked monomers) and in the ratio of syringyl to guaiacyl monomers (S/G) was observed for three transgenic lines and the most drastic reduction (up to 50%) was correlated with the lowest level of CAD activity. Higher lignin extractability by mild alkali treatment was confirmed, and, in addition to a tenfold increase in C6-C1 aldehydes, coniferyl aldehyde was detected by high-performance liquid chromatography in the alkali extracts from the xylem of transgenic plants. In-situ polymerisation of cinnamyl aldehydes in stem sections of untransformed tobacco gave a xylem cell wall coloration strikingly similar to the reddish-brown coloration of the xylem of antisense CAD-down-regulated plants. Overall, these data provide new arguments for the involvement of polymerised cinnamyl aldehydes in the formation of the red-coloured xylem of CAD-down-regulated plants. Received: 24 January 1997 / Accepted: 14 May 1997 |
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Keywords: | : Antisense strategy Cinnamyl alcohol dehydrogenase Cinnamyl aldehyde Nicotiana Transgenic tobacco Lignin |
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