title: Development of high amylose wheat through TILLING.
abstract: BACKGROUND
  Wheat (Triticum spp.) is an important source of food worldwide and the focus of considerable efforts to identify new combinations of genetic diversity for crop improvement. In particular, wheat starch composition is a major target for changes that could benefit human health. Starches with increased levels of amylose are of interest because of the correlation between higher amylose content and elevated levels of resistant starch, which has been shown to have beneficial effects on health for combating obesity and diabetes. TILLING (Targeting Induced Local Lesions in Genomes) is a means to identify novel genetic variation without the need for direct selection of phenotypes.
  
  
  RESULTS
  Using TILLING to identify novel genetic variation in each of the A and B genomes in tetraploid durum wheat and the A, B and D genomes in hexaploid bread wheat, we have identified mutations in the form of single nucleotide polymorphisms (SNPs) in starch branching enzyme IIa genes (SBEIIa). Combining these new alleles of SBEIIa through breeding resulted in the development of high amylose durum and bread wheat varieties containing 47-55% amylose and having elevated resistant starch levels compared to wild-type wheat. High amylose lines also had reduced expression of SBEIIa RNA, changes in starch granule morphology and altered starch granule protein profiles as evaluated by mass spectrometry.
  
  
  CONCLUSIONS
  We report the use of TILLING to develop new traits in crops with complex genomes without the use of transgenic modifications. Combined mutations in SBEIIa in durum and bread wheat varieties resulted in lines with significantly increased amylose and resistant starch contents.
authors.affiliation: Arcadia Biosciences, Inc, Seattle, WA 98119, USA. ann.slade@arcadiabio.com
authors.forename: Ann J
authors.initials: AJ
authors.lastname: Slade
authors.forename: Cate
authors.initials: C
authors.lastname: McGuire
authors.forename: Dayna
authors.initials: D
authors.lastname: Loeffler
authors.forename: Jessica
authors.initials: J
authors.lastname: Mullenberg
authors.forename: Wayne
authors.initials: W
authors.lastname: Skinner
authors.forename: Gia
authors.initials: G
authors.lastname: Fazio
authors.forename: Aaron
authors.initials: A
authors.lastname: Holm
authors.forename: Kali M
authors.initials: KM
authors.lastname: Brandt
authors.forename: Michael N
authors.initials: MN
authors.lastname: Steine
authors.forename: John F
authors.initials: JF
authors.lastname: Goodstal
authors.forename: Vic C
authors.initials: VC
authors.lastname: Knauf
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000235:genetics* / Q000378:metabolism; D000483:Alleles; D019943:Amino Acid Substitution; D000688:Amylose / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D001947:Breeding; D018744:DNA, Plant / Q000235:genetics; D056625:Endosperm / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D018745:Genome, Plant / Q000235:genetics*; D005838:Genotype; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011123:Polyploidy; D020033:Protein Isoforms / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D017422:Sequence Analysis, DNA; D013213:Starch / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D020033:Protein Isoforms; D018749:RNA, Plant; D013213:Starch; D000688:Amylose; D015061:1,4-alpha-Glucan Branching Enzyme