title: Manipulating the phenolic acid content and digestibility of italian ryegrass (Lolium multiflorum) by vacuolar-targeted expression of a fungal ferulic acid esterase.
abstract: In grass cell walls, ferulic acid esters linked to arabinosyl residues in arabinoxylans play a key role in crosslinking hemicellulose. Although such crosslinks have a number of important roles in the cell wall, they also hinder the rate and extent of cell wall degradation by ruminant microbes and by fungal glycohydrolyase enzymes. Ferulic acid esterase (FAE) can release both monomeric and dimeric ferulic acids from arabinoxylans making the cell wall more susceptible to further enzymatic attack. Transgenic plants of Lolium multiflorum expressing a ferulic acid esterase gene from Aspergillus niger, targeted to the vacuole under a constitutive rice actin promoter, have been produced following microprojectile bombardment of embryogenic cell cultures. The level of FAE activity was found to vary with leaf age and was highest in young leaves. FAE expression resulted in the release of monomeric and dimeric ferulic acids from cell walls on cell death and this was enhanced severalfold by the addition of exogenous beta-1,4-endoxylanase. We also show that a number of plants expressing FAE had reduced levels of cell wall esterified monomeric and dimeric ferulates and increased in vitro dry-matter digestibility compared with nontransformed plants.
authors.affiliation: Plant Animal and Microbial Science, Department, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth SY23 3EB, Wales, UK.
authors.forename: Marcia M de O
authors.initials: MM
authors.lastname: Buanafina
authors.forename: Tim
authors.initials: T
authors.lastname: Langdon
authors.forename: Barbara
authors.initials: B
authors.lastname: Hauck
authors.forename: Sue J
authors.initials: SJ
authors.lastname: Dalton
authors.forename: Phil
authors.initials: P
authors.lastname: Morris
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D001234:Aspergillus niger / Q000235:genetics / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D004063:Digestion; D024861:Genetic Enhancement / Q000379:methods; D062385:Hydroxybenzoates / Q000737:chemistry* / Q000378:metabolism*; D008129:Lolium / Q000737:chemistry* / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000737:chemistry / Q000378:metabolism; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000378:metabolism; D014617:Vacuoles / Q000737:chemistry / Q000378:metabolism
chemical_list: D062385:Hydroxybenzoates; D011994:Recombinant Proteins; D002265:Carboxylic Ester Hydrolases; C070196:feruloyl esterase; C017616:phenolic acid