title: Characterization of opaque2 modifier QTLs and candidate genes in recombinant inbred lines derived from the K0326Y quality protein maize inbred.
abstract: Quality protein maize (QPM) is a high lysine-containing corn that is based on genetic modification of the opaque2 (o2) mutant. In QPM, modifier genes convert the starchy endosperm of o2 to the vitreous phenotype of wild type maize. There are multiple, unlinked o2 modifier loci (Opm) in QPM and their nature and mode of action are unknown. We previously identified seven Opm QTLs and characterized 16 genes that are differentially up-regulated at a significant level in K0326Y QPM, compared to the starchy endosperm mutant W64Ao2. In order to further characterize these Opm QTLs and the genes up-regulated in K0326Y QPM, we created a population of 314 recombinant inbred lines (RILs) from a cross between K0326Y QPM and W64Ao2. The RILs were characterized for three traits associated with endosperm texture: vitreousness, density and hardness. Genetic linkage analysis of the RIL population confirmed three of the previously identified QTLs associated with o2 endosperm modification in K0326Y QPM. Many of the genes up-regulated in K0326Y QPM showed substantially higher levels of expression in vitreous compared with opaque RILs. These included genes associated with the upstream regulation of the ethylene response pathway, and a gene encoding a regulatory subunit of pyrophosphate-dependent fructose-6-phosphate 1-phosphotransferase, an adaptive enzyme of the glycolytic pathway.
authors.affiliation: Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68588-0665, USA. dholding2@unl.edu
authors.forename: David R
authors.initials: DR
authors.lastname: Holding
authors.forename: Brenda G
authors.initials: BG
authors.lastname: Hunter
authors.forename: John P
authors.initials: JP
authors.lastname: Klingler
authors.forename: Song
authors.initials: S
authors.lastname: Wu
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Guo
authors.forename: Bryan C
authors.initials: BC
authors.lastname: Gibbon
authors.forename: Rongling
authors.initials: R
authors.lastname: Wu
authors.forename: Jan-Michele
authors.initials: JM
authors.lastname: Schulze
authors.forename: Rudolf
authors.initials: R
authors.lastname: Jung
authors.forename: Brian A
authors.initials: BA
authors.lastname: Larkins
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D056726:Genetic Association Studies; D006244:Hardness; D007178:Inbreeding; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000235:genetics*; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics*; D040641:Quantitative Trait Loci / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D011995:Recombination, Genetic / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*; D015028:Zein / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C102290:OHP1 protein, Zea mays; D010940:Plant Proteins; D014157:Transcription Factors; D015028:Zein