Poster: Cell Walls

Abs # 1263: Genetic manipulation of lignin biosynthesis for improving forage digestibility of tall fescue (Festuca arundinacea)

Presenter:	Chen, Lei , clei@noble.org
Authors	Chen, Lei  (A)   Auh, Chungkyoon  (A)   Dowling, Paul  (A)   Chen, Fang  (B)   Hopkins, Andy  (A)   Dixon, Richard A.  (B)   Wang, Zengyu  (A)
Affiliations:	(A): Forage biotechnology group, Samuel Roberts Noble Foundation (B): Plant biology division, Samuel Roberts Noble Foundation

Tall fescue (Festuca arundinacea) is the predominant cool-season forage grass in the United States. Lignification of plant cell walls is a major factor limiting forage digestibility and concomitantly animal productivity. Improvement in forage grass cell wall digestibility has become an important goal of many plant-ruminant animal research programs. Cinnamyl alcohol dehydrogenase (CAD) and caffeic acid O- methyltransferase (COMT) are key enzymes involved in lignin biosynthesis. CAD and COMT cDNA sequences were cloned from tall fescue. Transgenic tall fescue plants carrying either sense or antisense CAD and COMT gene constructs were obtained by microprojectile bombardment of single genotype-derived embryogenic suspension cells. Severely reduced mRNA levels and significantly decreased enzymatic activities were found in four transgenic lines. These CAD and COMT down-regulated tall fescue plants had reduced lignin content and altered lignin composition. No significant changes in cellulose, hemicellulose, neutral sugar composition, p-coumaric acid and ferulic acid levels were observed in the transgenic plants. In vitro dry matter digestibility increased by 7.2% to 10.5% in the transgenic lines, thus providing novel germplasm to be used for the development of grass cultivars with improved forage quality.