title: Effect of lignin content and subunit composition on digestibility in clones of timothy (Phleum pratense L.).
abstract: Lignin amount and subunit composition were analyzed from stems and leaf sheaths of timothy (Phleum pratense L.) clones of different in vitro digestibility. Lignin concentration in stems and leaf sheaths was higher in clones of low digestibility than those of high digestibility. No change in lignin concentration occurred in stems as digestibility decreased. Intriguingly, the lignin concentration was lower and the syringyl/guaiacyl (S/G) ratio was higher in stems compared to leaf sheaths at all developmental stages studied. The developmental-associated decrease in digestibility correlated with the increase in S units in lignin in stems and leaf sheaths and in the amounts of p-coumaric acid and ferulic acid residues in the cell wall of stems. Yields of copper oxidation products increased in stems during maturation indicating qualitative changes in the lignin structure. This correlated strongly with the developmentally linked decrease in digestibility. The information obtained is valuable for breeding and for DNA marker development.
authors.affiliation: Department of Agricultural Sciences, University of Helsinki , FI-00014 Helsinki, Finland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kärkönen
authors.forename: Tarja
authors.initials: T
authors.lastname: Tapanila
authors.forename: Tapio
authors.initials: T
authors.lastname: Laakso
authors.forename: Mervi M
authors.initials: MM
authors.lastname: Seppänen
authors.forename: Mika
authors.initials: M
authors.lastname: Isolahti
authors.forename: Maarit
authors.initials: M
authors.lastname: Hyrkäs
authors.forename: Perttu
authors.initials: P
authors.lastname: Virkajärvi
authors.forename: Pekka
authors.initials: P
authors.lastname: Saranpää
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D019976:Cloning, Organism; D004032:Diet / Q000662:veterinary*; D004043:Dietary Fiber / Q000032:analysis* / Q000378:metabolism; D004063:Digestion; D005387:Finland; D008031:Lignin / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D008954:Models, Biological; D015394:Molecular Structure; D031784:Phleum / Q000737:chemistry* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D012418:Ruminants
chemical_list: D004043:Dietary Fiber; D008031:Lignin
keywords: cell wall; digestibility; ferulic acid; lignin amount; lignin linkage structure; lignin subunit composition; timothy