title: ChAy/Bx, a novel chimeric high-molecular-weight glutenin subunit gene apparently created by homoeologous recombination in Triticum turgidum ssp. dicoccoides.
abstract: High-molecular-weight glutenin subunits (HMW-GSs) are of considerable interest, because they play a crucial role in determining dough viscoelastic properties and end-use quality of wheat flour. In this paper, ChAy/Bx, a novel chimeric HMW-GS gene from Triticum turgidum ssp. dicoccoides (AABB, 2n=4x=28) accession D129, was isolated and characterized. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed that the electrophoretic mobility of the glutenin subunit encoded by ChAy/Bx was slightly faster than that of 1Dy12. The complete ORF of ChAy/Bx contained 1,671 bp encoding a deduced polypeptide of 555 amino acid residues (or 534 amino acid residues for the mature protein), making it the smallest HMW-GS gene known from Triticum species. Sequence analysis showed that ChAy/Bx was neither a conventional x-type nor a conventional y-type subunit gene, but a novel chimeric gene. Its first 1305 nt sequence was highly homologous with the corresponding sequence of 1Ay type genes, while its final 366 nt sequence was highly homologous with the corresponding sequence of 1Bx type genes. The mature ChAy/Bx protein consisted of the N-terminus of 1Ay type subunit (the first 414 amino acid residues) and the C-terminus of 1Bx type subunit (the final 120 amino acid residues). Secondary structure prediction showed that ChAy/Bx contained some domains of 1Ay subunit and some domains of 1Bx subunit. The special structure of this HMW glutenin chimera ChAy/Bx subunit might have unique effects on the end-use quality of wheat flour. Here we propose that homoeologous recombination might be a novel pathway for allelic variation or molecular evolution of HMW-GSs.
authors.affiliation: Triticeae Research Institute, Sichuan Agricultural University, Wenjiang 611130, China; Key Laboratory of Crop Genetic Resources and Improvement, Ministry of Education, Sichuan Agricultural University, Ya'an 625014, China.
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Guo
authors.forename: Zhe-Guang
authors.initials: ZG
authors.lastname: Bi
authors.forename: Bi-Hua
authors.initials: BH
authors.lastname: Wu
authors.forename: Zhen-Zhen
authors.initials: ZZ
authors.lastname: Wang
authors.forename: Ji-Liang
authors.initials: JL
authors.lastname: Hu
authors.forename: You-Liang
authors.initials: YL
authors.lastname: Zheng
authors.forename: Deng-Cai
authors.initials: DC
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D017343:Genes, Plant; D005983:Glutens / Q000235:genetics*; D059765:Homologous Recombination / Q000502:physiology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D050506:Mutant Chimeric Proteins / Q000235:genetics*; D016366:Open Reading Frames / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014908:Triticum / Q000235:genetics*
chemical_list: D050506:Mutant Chimeric Proteins; D021122:Protein Subunits; D005983:Glutens; C037302:glutenin
keywords: Allelic variation; CTAB; Chimeric gene; Evolution; GISH; HMW-GS; High-molecular-weight glutenin subunit; Homoeologous recombination; IPTG; InDels; LMW-GS; NCBI; National Center for Biotechnology Information; ORF; PCR; SDS-PAGE; SNP; Triticum turgidum ssp. dicoccoides; aa; amino acid(s); base pair(s); bp; cetyltrimethyl ammonium bromide; dNTPs; deoxyribonucleoside triphosphates; genomic in situ hybridization; high-molecular-weight glutenin subunit; insertions and deletions; isopropyl-β-Δ-thiogalactopyranoside; low-molecular-weight glutenin subunit; open reading frame; polymerase chain reaction; single nucleotide polymorphism; sodium dodecyl sulfate polyacrylamide gel electrophoresis