title: Functional relationships of phytoene synthase 1 alleles on chromosome 7A controlling flour colour variation in selected Australian wheat genotypes.
abstract: Flour colour measured as a Commission Internationale de l'Eclairage (CIE) b* value is an important wheat quality attribute for a range of end-products, with genes and enzymes of the xanthophyll biosynthesis pathway providing potential sources of trait variation. In particular, the phytoene synthase 1 (Psy1) gene has been associated with quantitative trait loci (QTL) for flour b* colour variation. Several Psy1 alleles on chromosome 7A (Psy-A1) have been described, along with proposed mechanisms for influencing flour b* colour. This study sought to identify evolutionary relationships among known Psy-A1 alleles, to establish which Psy-A1 alleles are present in selected Australian wheat genotypes and establish their role in controlling variation for flour b* colour via QTL analysis. Phylogenetic analyses showed seven of eight known Psy-A1 alleles clustered with sequences from T. urartu, indicating the majority of alleles in Australian germplasm share a common evolutionary lineage. In this regard, Psy-A1a, Psy-A1c, Psy-A1e and Psy-A1p were common in Australian genotypes with flour b* colour ranging from white to yellow. In contrast Psy-A1s was found to be related to A. speltoides, indicating a possible A-B genome translocation during wheat polyploidisation. A new allele Psy-A1t (similar to Psy-A1s) was discovered in genotypes with yellow flour, with QTL analyses indicating Psy-A1t strongly influences flour b* colour in Australian germplasm. QTL LOD value maxima did not coincide with Psy-A1 gene locus in two of three populations and, therefore, Psy-A1a and Psy-A1p may not be involved in flour colour. Instead two other QTL were identified, one proximal and one distal to Psy-A1 in Australian wheat lines. Comparison of Psy-A1t and Psy-A1p predicted protein sequences suggests differences in putative sites for post-translational modification may influence enzyme activity and subsequent xanthophyll accumulation in the wheat endosperm. Psy-A1a and Psy-A1p were not involved in flour b* colour variation, indicating other genes control variation on chromosome 7A in some wheat genotypes.
authors: Department of Agriculture and Food Western Australia, 3 Baron Hay Ct, South Perth, WA, 6151, Australia.
authors: A C
authors: AC
authors: Crawford
authors: K
authors: K
authors: Stefanova
authors: W
authors: W
authors: Lambe
authors: R
authors: R
authors: McLean
authors: R
authors: R
authors: Wilson
authors: I
authors: I
authors: Barclay
authors: M G
authors: MG
authors: Francki
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism; D000483:Alleles; D000595:Amino Acid Sequence; D001315:Australia; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003116:Color; D003433:Crosses, Genetic; D018744:DNA, Plant / Q000235:genetics; D005433:Flour; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005838:Genotype; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D040641:Quantitative Trait Loci; D014908:Triticum / Q000201:enzymology* / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D019883:Alkyl and Aryl Transferases; D051232:Geranylgeranyl-Diphosphate Geranylgeranyltransferase