title: Effects of starch synthase IIa gene dosage on grain, protein and starch in endosperm of wheat.
abstract: Starch synthases (SS) are responsible for elongating the alpha-1,4 glucan chains of starch. A doubled haploid population was generated by crossing a line of wheat, which lacks functional ssIIa genes on each genome (abd), and an Australian wheat cultivar, Sunco, with wild type ssIIa alleles on each genome (ABD). Evidence has been presented previously indicating that the SGP-1 (starch granule protein-1) proteins present in the starch granule in wheat are products of the ssIIa genes. Analysis of 100 progeny lines demonstrated co-segregation of the ssIIa alleles from the three genomes with the SGP-1 proteins, providing further evidence that the SGP-1 proteins are the products of the ssIIa genes. From the progeny lines, 40 doubled haploid lines representing the eight possible genotypes for SSIIa (ABD, aBD, AbD, ABd, abD, aBd, Abd, abd) were characterized for their grain weight, protein content, total starch content and starch properties. For some properties (chain length distribution, pasting properties, swelling power, and gelatinization properties), a progressive change was observed across the four classes of genotypes (wild type, single nulls, double nulls and triple nulls). However, for other grain properties (seed weight and protein content) and starch properties (total starch content, granule morphology and crystallinity, granule size distribution, amylose content, amylose-lipid dissociation properties), a statistically significant change only occurred for the triple nulls, indicating that all three genes had to be missing or inactive for a change to occur. These results illustrate the importance of SSIIa in controlling grain and starch properties and the importance of amylopectin fine structure in controlling starch granule properties in wheat.
authors.affiliation: CSIRO Food Futures Flagship, PO Box 93, North Ryde, NSW 1670, Australia.
authors.forename: Christine
authors.initials: C
authors.lastname: Konik-Rose
authors.forename: Jenny
authors.initials: J
authors.lastname: Thistleton
authors.forename: Helene
authors.initials: H
authors.lastname: Chanvrier
authors.forename: Ihwa
authors.initials: I
authors.lastname: Tan
authors.forename: Peter
authors.initials: P
authors.lastname: Halley
authors.forename: Michael
authors.initials: M
authors.lastname: Gidley
authors.forename: Behjat
authors.initials: B
authors.lastname: Kosar-Hashemi
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Oscar
authors.initials: O
authors.lastname: Larroque
authors.forename: Joseph
authors.initials: J
authors.lastname: Ikea
authors.forename: Steve
authors.initials: S
authors.lastname: McMaugh
authors.forename: Ahmed
authors.initials: A
authors.lastname: Regina
authors.forename: Sadequr
authors.initials: S
authors.lastname: Rahman
authors.forename: Matthew
authors.initials: M
authors.lastname: Morell
authors.forename: Zhongyi
authors.initials: Z
authors.lastname: Li
mesh_terms: D015415:Biomarkers; D018628:Gene Dosage; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D016133:Polymerase Chain Reaction; D012639:Seeds / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D013213:Starch / Q000096:biosynthesis* / Q000737:chemistry; D013214:Starch Synthase / Q000235:genetics* / Q000502:physiology; D014908:Triticum / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*
chemical_list: D015415:Biomarkers; D010940:Plant Proteins; D013213:Starch; C111377:starch synthase II; D013214:Starch Synthase