title: Effect of suppression of arabinoxylan synthetic genes in wheat endosperm on chain length of arabinoxylan and extract viscosity.
abstract: Arabinoxylan (AX) is the dominant component within wheat (Triticum aestivum L.) endosperm cell walls, accounting for 70% of the polysaccharide. The viscosity of aqueous extracts from wheat grain is a key trait influencing the processing for various end uses, and this is largely determined by the properties of endosperm AX. We have previously shown dramatic effects on endosperm AX in transgenic wheat by down-regulating either TaGT43_2 or TaGT47_2 genes (orthologues to IRX9 and IRX10 in Arabidopsis, respectively) implicated in AX chain extension and the TaXAT1 gene responsible for monosubstitution by 3-linked arabinose. Here, we use these transgenic lines to investigate the relationship between amounts of AX in soluble and insoluble fractions, the chain-length distribution of these measured by intrinsic viscosity and the overall effect on extract viscosity. In transgenic lines expressing either the TaGT43_2 or TaGT47_2 RNAi transgenes, the intrinsic viscosities of water-extractable (WE-AX) and of a water-insoluble alkaline-extracted fraction (AE-AX) were decreased by between 10% and 50% compared to control lines. In TaXAT1 RNAi lines, there was a 15% decrease in intrinsic viscosity of WE-AX but no consistent effect on that of AE-AX. All transgenic lines showed decreases in extract viscosity with larger effects in TaGT43_2 and TaGT47_2 RNAi lines (by up to sixfold) than in TaXAT1 RNAi lines (by twofold). These effects were explained by the decreases in amount and chain length of WE-AX, with decreases in amount having the greater influence. Extract viscosity from wheat grain can therefore be greatly decreased by suppression of single gene targets.
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, UK.
authors.forename: Jackie
authors.initials: J
authors.lastname: Freeman
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Lovegrove
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, UK.
authors.forename: Mark David
authors.initials: MD
authors.lastname: Wilkinson
authors.affiliation: INRA Centre de Recherche Angers-Nantes, Nantes, France.
authors.forename: Luc
authors.initials: L
authors.lastname: Saulnier
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, UK.
authors.forename: Peter Robert
authors.initials: PR
authors.lastname: Shewry
authors.affiliation: Plant Biology and Crop Science, Rothamsted Research, Harpenden, UK.
authors.forename: Rowan Andrew Craig
authors.initials: RA
authors.lastname: Mitchell
mesh_terms: D000468:Alkalies / Q000737:chemistry; D053898:Biosynthetic Pathways / Q000235:genetics*; D002850:Chromatography, Gel; D056625:Endosperm / Q000378:metabolism*; D005433:Flour; D017343:Genes, Plant; D006720:Homozygote; D010936:Plant Extracts / Q000737:chemistry; D034622:RNA Interference; D014908:Triticum / Q000235:genetics* / Q000378:metabolism*; D014783:Viscosity; D014867:Water / Q000737:chemistry; D014990:Xylans / Q000096:biosynthesis* / Q000737:chemistry*
chemical_list: D000468:Alkalies; D010936:Plant Extracts; D014990:Xylans; D014867:Water; C085118:arabinoxylan
keywords: Type II cell wall; grass xylan; wheat flour-processing properties
references.citation: Plant J. 2007 Dec;52(6):1154-68
references.pmid: 17944810
references.citation: Plant J. 2014 Oct;80(2):207-15
references.pmid: 25139408
references.citation: Front Plant Sci. 2014 Sep 11;5:456
references.pmid: 25309555
references.citation: Plant Cell. 2007 Feb;19(2):549-63
references.pmid: 17322407
references.citation: Plant Physiol. 2010 Mar;152(3):1209-18
references.pmid: 20089768
references.citation: J Agric Food Chem. 2008 Nov 12;56(21):9740-9
references.pmid: 18921978
references.citation: Carbohydr Res. 2001 Feb 15;330(3):365-72
references.pmid: 11270815
references.citation: Plant J. 2009 Feb;57(4):732-46
references.pmid: 18980662
references.citation: Biomacromolecules. 2011 Jul 11;12(7):2633-41
references.pmid: 21598942
references.citation: Analyst. 1982 Mar;107(1272):307-18
references.pmid: 6283946
references.citation: PLoS One. 2014 Feb 21;9(2):e89620
references.pmid: 24586916
references.citation: Proc Natl Acad Sci U S A. 2012 Jan 17;109(3):989-93
references.pmid: 22215597
references.citation: Plant Physiol. 2007 May;144(1):43-53
references.pmid: 17351055
references.citation: Plant Physiol. 2010 Sep;154(1):78-97
references.pmid: 20631319
references.citation: J Chromatogr A. 2000 Jan 7;866(1):97-104
references.pmid: 10681013
references.citation: J Agric Food Chem. 2010 Sep 8;58(17):9353-61
references.pmid: 20462191
references.citation: Proc Natl Acad Sci U S A. 2010 Oct 5;107(40):17409-14
references.pmid: 20852069
references.citation: Biomacromolecules. 2008 Jul;9(7):2042-7
references.pmid: 18572963
references.citation: Plant Physiol. 2012 Feb;158(2):612-27
references.pmid: 22123899
references.citation: Plant Physiol. 2013 Sep;163(1):95-107
references.pmid: 23878080
references.citation: Plant J. 2014 Oct;80(2):197-206
references.pmid: 25141999
references.citation: Carbohydr Polym. 2013 Jul 1;96(1):31-8
references.pmid: 23688451