title: Genome Wide Association Mapping for Arabinoxylan Content in a Collection of Tetraploid Wheats.
abstract: BACKGROUND
  Arabinoxylans (AXs) are major components of plant cell walls in bread wheat and are important in bread-making and starch extraction. Furthermore, arabinoxylans are components of soluble dietary fibre that has potential health-promoting effects in human nutrition. Despite their high value for human health, few studies have been carried out on the genetics of AX content in durum wheat.
  
  
  RESULTS
  The genetic variability of AX content was investigated in a set of 104 tetraploid wheat genotypes and regions attributable to AX content were identified through a genome wide association study (GWAS). The amount of arabinoxylan, expressed as percentage (w/w) of the dry weight of the kernel, ranged from 1.8% to 5.5% with a mean value of 4.0%. The GWAS revealed a total of 37 significant marker-trait associations (MTA), identifying 19 quantitative trait loci (QTL) associated with AX content. The highest number of MTAs was identified on chromosome 5A (seven), where three QTL regions were associated with AX content, while the lowest number of MTAs was detected on chromosomes 2B and 4B, where only one MTA identified a single locus. Conservation of synteny between SNP marker sequences and the annotated genes and proteins in Brachypodium distachyon, Oryza sativa and Sorghum bicolor allowed the identification of nine QTL coincident with candidate genes. These included a glycosyl hydrolase GH35, which encodes Gal7 and a glucosyltransferase GT31 on chromosome 1A; a cluster of GT1 genes on chromosome 2B that includes TaUGT1 and cisZog1; a glycosyl hydrolase that encodes a CelC gene on chromosome 3A; Ugt12887 and TaUGT1genes on chromosome 5A; a (1,3)-β-D-glucan synthase (Gsl12 gene) and a glucosyl hydrolase (Cel8 gene) on chromosome 7A.
  
  
  CONCLUSIONS
  This study identifies significant MTAs for the AX content in the grain of tetraploid wheat genotypes. We propose that these may be used for molecular breeding of durum wheat varieties with higher soluble fibre content.
authors.affiliation: Department of Soil, Plant and Food Sciences, Section of Genetics and Plant Breeding, University of Bari 'Aldo Moro', Via G. Amendola 165/A, Bari, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Marcotuli
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee, Scotland.
authors.forename: Kelly
authors.initials: K
authors.lastname: Houston
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee, Scotland.
authors.forename: Robbie
authors.initials: R
authors.lastname: Waugh
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, Australia.
authors.forename: Geoffrey B
authors.initials: GB
authors.lastname: Fincher
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, Australia.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Burton
authors.affiliation: Department of Soil, Plant and Food Sciences, Section of Genetics and Plant Breeding, University of Bari 'Aldo Moro', Via G. Amendola 165/A, Bari, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Blanco
authors.affiliation: Department of Soil, Plant and Food Sciences, Section of Genetics and Plant Breeding, University of Bari 'Aldo Moro', Via G. Amendola 165/A, Bari, Italy.
authors.forename: Agata
authors.initials: A
authors.lastname: Gadaleta
mesh_terms: D001499:Bayes Theorem; D053898:Biosynthetic Pathways / Q000235:genetics; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D030541:Databases, Genetic; D018506:Gene Expression Regulation, Plant; D005819:Genetic Markers; D018745:Genome, Plant; D055106:Genome-Wide Association Study; D005838:Genotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics; D019655:Quantitative Trait, Heritable; D012639:Seeds / Q000235:genetics; D057891:Tetraploidy; D014908:Triticum / Q000235:genetics*; D014990:Xylans / Q000235:genetics*
chemical_list: D005819:Genetic Markers; D014990:Xylans; C085118:arabinoxylan