Novel LMW glutenin subunit genes from wild emmer wheat (Triticum turgidum ssp. dicoccoides) in relation to Glu-3 evolution

• DOI: 10.1007/s00427-014-0484-x
• Publication Date: 2014-12-02T17:06:54Z
• Authors: Lumin Qin; Yu Liang; Daozheng Yang; Lei Sun; Guangmin Xia; Shuwei Liu
• Keywords: 2. Zero hunger; 0303 health sciences; Glutens; Molecular Sequence Data; Genes, Plant; Evolution, Molecular; Molecular Weight; 03 medical and health sciences; Amino Acid Sequence; Sequence Alignment; Phylogeny; Triticum; Prolamins

Four low-molecular-weight-isoleucine (LMW-i)-type and one novel chimeric (between LMW-i and LMW-methionine (m) types) low-molecular-weight glutenin subunit (LMW-GS) genes were characterized from wild emmer wheat (Triticum dicoccoides), designated as emmer-1 to emmer-5. All five LMW-GS genes possessed the same primary structure shared by other published LMW-GSs. The three genes emmer-1, emmer-3, and emmer-5 are similar, with the exception that emmer-3 and emmer-5 lost a few repeat motifs compared to emmer-1. Gene duplication and insertions/deletions of repeat motifs mediated through unequal crossing over may be responsible for the generation of these three Glu-3 alleles. Although the first residue of mature peptide of emmer-4 is isoleucine, it is not typical LMW-i-type LMW-GS. Phylogenetic analysis indicated that emmer-4 is located in the LMW-m subgroup, suggesting a closer relationship with LMW-m-type gene Y14104 of T. durum. Sequence alignment indicated that the emmer-4 is likely a chimeric gene generated by illegitimate recombination between LMW-i and LMW-m type. Unequal crossing over and illegitimate recombination are effective mechanisms for enriching both copy numbers and variations of LMW-GSs.