Present addresses: Department of Biological Sciences, SungKyunKwan University, Suwon 440-746, South Korea.
Improved forage digestibility of tall fescue (Festuca arundinacea) by transgenic down-regulation of cinnamyl alcohol dehydrogenase
Article first published online: 19 SEP 2003
Plant Biotechnology Journal
Volume 1, Issue 6, pages 437–449, November 2003
How to Cite
Chen, L., Auh, C.-K., Dowling, P., Bell, J., Chen, F., Hopkins, A., Dixon, R. A. and Wang, Z.-Y. (2003), Improved forage digestibility of tall fescue (Festuca arundinacea) by transgenic down-regulation of cinnamyl alcohol dehydrogenase. Plant Biotechnology Journal, 1: 437–449. doi: 10.1046/j.1467-7652.2003.00040.x
- Issue published online: 19 SEP 2003
- Article first published online: 19 SEP 2003
- Received 12 Jun 2003; revised 16 July 2003; accepted 18 July 2003.
- forage grass;
- lignin biosynthesis;
- tall fescue;
- transgenic plant
Lignification of cell walls during plant development has been identified as the major factor limiting forage digestibility and concomitantly animal productivity. cDNA sequences encoding a key lignin biosynthetic enzyme, cinnamyl alcohol dehydrogenase (CAD), were cloned from the widely grown monocotyledonous forage species tall fescue (Festuca arundinacea Schreb.). Recombinant tall fescue CAD expressed in E. coli exhibited the highest Vmax/Km values when coniferaldehyde and sinapaldehyde were used as substrates. Transgenic tall fescue plants carrying either sense or antisense CAD gene constructs were obtained by microprojectile bombardment of single genotype-derived embryogenic suspension cells. Severely reduced levels of mRNA transcripts and significantly reduced CAD enzymatic activities were found in two transgenic plants carrying sense and antisense CAD transgenes, respectively. These CAD down-regulated transgenic lines had significantly decreased lignin content and altered ratios of syringyl (S) to guaiacyl (G), G to p-hydroxyphenyl (H) and S to H units. No significant changes in cellulose, hemicellulose, neutral sugar composition, p-coumaric acid and ferulic acid levels were observed in the transgenic plants. Increases of in vitro dry matter digestibility of 7.2–9.5% were achieved in the CAD down-regulated lines, thus providing a novel germplasm to be used for the development of grass cultivars with improved forage quality.