Novel insights into the composition, variation, organization, and expression of the low-molecular-weight glutenin subunit gene family in common wheat

Abstract

Low-molecular-weight glutenin subunits (LMW-GS), encoded by a complex multigene family, play an important role in the processing quality of wheat flour. Although members of this gene family have been identified in several wheat varieties, the allelic variation and composition of LMW-GS genes in common wheat are not well understood. In the present study, using the LMW-GS gene molecular marker system and the full-length gene cloning method, a comprehensive molecular analysis of LMW-GS genes was conducted in a representative population, the micro-core collections (MCC) of Chinese wheat germplasm. Generally, >15 LMW-GS genes were identified from individual MCC accessions, of which 4–6 were located at the Glu-A3 locus, 3–5 at the Glu-B3 locus, and eight at the Glu-D3 locus. LMW-GS genes at the Glu-A3 locus showed the highest allelic diversity, followed by the Glu-B3 genes, while the Glu-D3 genes were extremely conserved among MCC accessions. Expression and sequence analysis showed that 9–13 active LMW-GS genes were present in each accession. Sequence identity analysis showed that all i-type genes present at the Glu-A3 locus formed a single group, the s-type genes located at Glu-B3 and Glu-D3 loci comprised a unique group, while high-diversity m-type genes were classified into four groups and detected in all Glu-3 loci. These results contribute to the functional analysis of LMW-GS genes and facilitate improvement of bread-making quality by wheat molecular breeding programmes.

Molecular characterization of novel LMW-i glutenin subunit genes from Triticum urartu Thum. ex Gandil.

“…Phylogenetic tree was constructed with MEGA5 software (Tamura et al 2011) using the complete coding sequences obtained together with the sequences of the LMW-i genes identified in common wheat by Zhang et al (2013), also as the LMW-i gene isolated from common wheat cv. 5.0.3 software (Biomatters Ltd.).…”

“…2). The GluA3-1 gene had up to three sets: the first one associated with A3-640/A3-649-2 genes described by Zhang et al (2013); the second with the A3-573/A3-620/A3-646a/A3-646b/A3-649-1 genes, and the third with A3-565/A3-568/A3-662-named in a previous study as A3-2, A3-3 and A3-4, respectively (Dong et al 2010). There were different groups within each cluster.…”

“…The other cluster (GluA3-3) showed two groups associated with A3-484 and A3-502, respectively. Numbers in nodes indicate bootstrap estimates from 1000 replications with the A3-662 sequence described by Zhang et al (2013). 2).…”

“…A recent study showed that there were at least 15 LMWGs genes in individual accessions of common wheat (Zhang et al 2013). The Glu-A3 locus showed the highest allelic diversity and Glu-B3 showed moderate diversity, whereas Glu-D3 was very low.…”

“…The Glu-A3 locus showed the highest allelic diversity and Glu-B3 showed moderate diversity, whereas Glu-D3 was very low. However, Zhang et al (2013) identified 4-6 genes (two for LMW-m and the rest for LMWi) suggesting that these last were organized in different haplotypes. However, Zhang et al (2013) identified 4-6 genes (two for LMW-m and the rest for LMWi) suggesting that these last were organized in different haplotypes.…”