title: Using the Hexaploid Nature of Wheat To Create Variability in Starch Characteristics.
abstract: In hexaploid crops, such as bread wheat, it should be possible to fine-tune phenotypic traits by identifying wild-type and null genes from each of the three genomes and combining them in a calculated manner. Here, we demonstrate this with gene combinations for two starch synthesis genes, SSIIa and GBSSI. Lines with inactive copies of both enzymes show a very dramatic change in phenotype, so to create intermediate phenotypes, we used marker-assisted selection to develop near-isogenic lines (NILs) carrying homozygous combinations of null alleles. For both genes, gene dosage effects follow the order B > D ≥ A; therefore, we completed detailed analysis of starch characteristics for NIL 3-3, which is null for the B-genome copy of the SSIIa and GBSSI genes, and NIL 5-5, which has null mutations in the B- and D-genome-encoded copies of both of these genes. The effects of the combinations on phenotypic traits followed the order expected on the basis of genotype, with NIL 5-5 showing the largest differences from the wild type, while NIL 3-3 characteristics were intermediate between NIL 5-5 and the wild type. Differences among genotypes were significant for many starch characteristics, including percent amylose, chain length distribution, gelatinization temperature, retrogradation, and pasting properties, and these differences appeared to translate into improvements in end-product quality, since bread made from type 5-5 flour showed a 3 day lag in staling.
authors.affiliation: Nippon Flour Mills Company, Limited , Atsugi, Kanagawa 243-0041, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Inokuma
authors.affiliation: Bioriginal Food & Science Corporation , Saskatoon, Saskatchewan S7J 0R1, Canada.
authors.forename: Patricia
authors.initials: P
authors.lastname: Vrinten
authors.affiliation: Nippon Flour Mills Company, Limited , Atsugi, Kanagawa 243-0041, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Shimbata
authors.affiliation: Nippon Flour Mills Company, Limited , Atsugi, Kanagawa 243-0041, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Sunohara
authors.affiliation: Tohoku National Agriculture Research Center , Morioka, Iwate 020-0198, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.affiliation: Tohoku National Agriculture Research Center , Morioka, Iwate 020-0198, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Saito
authors.affiliation: Tohoku National Agriculture Research Center , Morioka, Iwate 020-0198, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Taniguchi
authors.affiliation: Tohoku National Agriculture Research Center , Morioka, Iwate 020-0198, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D018628:Gene Dosage; D005838:Genotype; D011123:Polyploidy; D013213:Starch / Q000737:chemistry* / Q000378:metabolism; D014908:Triticum / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D013213:Starch
keywords: GBSSI; SSIIa; hexaploid; near-isogenic line; starch; variability; wheat