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

Abstract

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.

Characterization of novel LMW glutenin subunit genes at the Glu-M3 locus from Aegilops comosa

“…The LMW-m-, LMW-i-, and LMW-s-type subunits are extensively characterized in the Triticum species (Lee et al 2016;Luo et al 2015;Qin et al 2015). However, to our knowledge, the LMW-l-type genes were only identified in the wild source Ae.…”

“…comosa and other Triticeae species. These genes included AB062872 (Ikeda et al 2002), AY263369 (Zhao et al 2004), AB164416, DQ357057, DQ357058 (Zhao et al 2006), and AY542896 (Cloutier et al 2001) from T. aestivum; KF562511, KF562512, KF562513, KF562514 (Qin et al 2015), and DQ217663 from T. dicoccoides; EU594332, EU594333, EU594334, EU594335, EU594336, EU594338, and EU594339 (Wang et al 2011) from Ae. comosa; AY606257 and AY646285 (Luo et al 2005) from Agropyron elongatum; DQ345449 and DQ307389 from T. monococcum; AY585350 (Johal et al 2004) and AY841014 from Ae.…”

Characterization of novel LMW-i genes with nine cysteine residues from Chinese wheat landraces (Triticum aestivum L.) and analysis of their functional properties on dough mixing

“…Modifications in the number and distribution of cysteines in LMW-GS may lead to different gluten macropolymers (D'Ovidio and Masci 2004). Novel LMW-GS, such as chimera of LMW-i/-m, -s/-m, and -m/-m, as well as -m/-i, have been identified from Chinese Xinjiang winter wheat landraces (Hu et al 2020) and other wheat genetic resources (Li et al 2008a;Qin et al 2015;Cuesta et al 2017). Some of these chimeric genes showed an altered number and distribution of cysteines in comparison with their parental genes, thus modifying the structure of gluten polymers and the dough quality via intra-and intermolecular disulfide bonds (Li et al 2008b;Cuesta et al 2017;Qin et al 2015;Hu et al 2020).…”