title: Assessment of the protein quality of 15 new northern adapted cultivars of quality protein maize using amino acid analysis.
abstract: Amino acid determinations were carried out on 15 new northern adapted cultivars of quality protein maize (QPM) containing opaque-2 modifier genes to ascertain whether their amino acid scoring patterns could be used to select high-lysine QPM genotypes and to assess their protein quality. Total protein in these cultivars ranged from 8.0 to 10.2% compared to two commercial maize varieties, Dekalb DK435 (7.9%) and Pioneer 3925 (10.3%). Four of these QPM genotypes, QPM-C26, QPM-C21, QPM-C79, and QPM-C59, contained high levels of lysine (4.43-4.58 g of lysine/100 g of protein), whereas the remaining varied from 3.43 to 4.21 g of lysine/100 g of protein, compared to Dekalb DK435 and Pioneer 3925, which contained 2.9 and 3. 1 g of lysine/100 g of protein, respectively. Although lysine is the first limiting amino acid in QPM inbreds, the high-lysine QPM genotypes may supply approximately 70.2-72.6% of human protein requirements, compared to 46.2% for Dekalb DK435 and 50.1% for Pioneer 3925, 55-63% for oats, and 59-60.3% for barley. Northern adapted QPM genotypes may have the potential to increase their lysine content even further, either by an increase in specific high-lysine-containing nonzein proteins, such as the synthesis of factor EF-1a, or by a further reduction in the 19 and 22 kDa alpha-zein in the endosperm or both. This knowledge could assist maize breeders in the selection of new high-performance QPM genotypes with improved protein quality and quantity.
authors.affiliation: Eastern Cereal and Oilseed Research Centre, Central Experimental Farm, Research Branch, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6. zarkadascg@em.agr.ca
authors.forename: C G
authors.initials: CG
authors.lastname: Zarkadas
authors.forename: R I
authors.initials: RI
authors.lastname: Hamilton
authors.forename: Z R
authors.initials: ZR
authors.lastname: Yu
authors.forename: V K
authors.initials: VK
authors.lastname: Choi
authors.forename: S
authors.initials: S
authors.lastname: Khanizadeh
authors.forename: N G
authors.initials: NG
authors.lastname: Rose
authors.forename: P L
authors.initials: PL
authors.lastname: Pattison
mesh_terms: D000596:Amino Acids / Q000032:analysis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics; D004044:Dietary Proteins; D017343:Genes, Plant; D006801:Humans; D009751:Nutritional Requirements; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D013045:Species Specificity; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D003313:Zea mays / Q000737:chemistry* / Q000235:genetics*
chemical_list: D000596:Amino Acids; D004268:DNA-Binding Proteins; D004044:Dietary Proteins; D010940:Plant Proteins; D014157:Transcription Factors; C067402:opaque-2 protein, Zea mays