Over-expression of specific HvCslF cellulose synthase-like genes in transgenic barley increases the levels of cell wall (1,3;1,4)-β-d-glucans and alters their fine structure.
Cell walls in commercially important cereals and grasses are characterized by the presence of (1,3;1,4)-β-d-glucans. These polysaccharides are beneficial constituents of human diets, where they can reduce the risk of hypercholesterolemia, type II diabetes, obesity and colorectal cancer. The biosynthesis of cell wall (1,3;1,4)-β-d-glucans in the Poaceae is mediated, in part at least, by the cellulose synthase-like CslF family of genes. Over-expression of the barley CslF6 gene under the control of an endosperm-specific oat globulin promoter results in increases of more than 80% in (1,3;1,4)-β-d-glucan content in grain of transgenic barley. Analyses of (1,3;1,4)-β-d-glucan fine structure indicate that individual CslF enzymes might direct the synthesis of (1,3;1,4)-β-d-glucans with different structures. When expression of the CslF6 transgene is driven by the Pro35S promoter, the transgenic lines have up to sixfold higher levels of (1,3;1,4)-β-d-glucan in leaves, but similar levels as controls in the grain. Some transgenic lines of Pro35S:CslF4 also show increased levels of (1,3;1,4)-β-d-glucans in grain, but not in leaves. Thus, the effects of CslF genes on (1,3;1,4)-β-d-glucan levels are dependent not only on the promoter used, but also on the specific member of the CslF gene family that is inserted into the transgenic barley lines. Altering (1,3;1,4)-β-d-glucan levels in grain and vegetative tissues will have potential applications in human health, where (1,3;1,4)-β-d-glucans contribute to dietary fibre, and in tailoring the composition of biomass cell walls for the production of bioethanol from cereal crop residues and grasses.
Burton
Rachel A
RA
School of Agriculture, Food and Wine, and the Australian Centre for Plant Functional Genomics, University of Adelaide, Glen Osmond, SA, Australia.
Collins
Helen M
HM
Kibble
Natalie A J
NA
Smith
Jessica A
JA
Shirley
Neil J
NJ
Jobling
Stephen A
SA
Henderson
Marilyn
M
Singh
Rohan R
RR
Pettolino
Filomena
F
Wilson
Sarah M
SM
Bird
Anthony R
AR
Topping
David L
DL
Bacic
Antony
A
Fincher
Geoffrey B
GB
D002473:Cell Wall / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D004043:Dietary Fiber / Q000378:metabolism; D005818:Genetic Engineering; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D030821:Plants, Genetically Modified / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D047071:beta-Glucans / Q000378:metabolism*
D004043:Dietary Fiber; D010940:Plant Proteins; D012333:RNA, Messenger; D047071:beta-Glucans; D005964:Glucosyltransferases