Composition, variation, expression and evolution of low-molecular-weight glutenin subunit genes in Triticum urartu

Abstract

BackgroundWheat (AABBDD, 2n = 6x = 42) is a major dietary component for many populations across the world. Bread-making quality of wheat is mainly determined by glutenin subunits, but it remains challenging to elucidate the composition and variation of low-molecular-weight glutenin subunits (LMW-GS) genes, the major components for glutenin subunits in hexaploid wheat. This problem, however, can be greatly simplified by characterizing the LMW-GS genes in Triticum urartu, the A-genome donor of hexaploid wheat. In the present study, we exploited the high-throughput molecular marker system, gene cloning, proteomic methods and molecular evolutionary genetic analysis to reveal the composition, variation, expression and evolution of LMW-GS genes in a T. urartu population from the Fertile Crescent region.ResultsEight LMW-GS genes, including four m-type, one s-type and three i-type, were characterized in the T. urartu population. Six or seven genes, the highest number at the Glu-A3 locus, were detected in each accession. Three i-type genes, each containing more than six allelic variants, were tightly linked because of their co-segregation in every accession. Only 2-3 allelic variants were detected for each m- and s-type gene. The m-type gene, TuA3-385, for which homologs were previously characterized only at Glu-D3 locus in common wheat and Aegilops tauschii, was detected at Glu-A3 locus in T. urartu. TuA3-460 was the first s-type gene identified at Glu-A3 locus. Proteomic analysis showed 1-4 genes, mainly i-type, expressed in individual accessions. About 62% accessions had three active i-type genes, rather than one or two in common wheat. Southeastern Turkey might be the center of origin and diversity for T. urartu due to its abundance of LMW-GS genes/genotypes. Phylogenetic reconstruction demonstrated that the characterized T. urartu might be the direct donor of the Glu-A3 locus in common wheat varieties.ConclusionsCompared with the Glu-A3 locus in common wheat, a large number of highly diverse LMW-GS genes and active genes were characterized in T. urartu, demonstrating that this progenitor might provide valuable genetic resources for LMW-GS genes to improve the quality of common wheat. The phylogenetic analysis provided molecular evidence and confirmed that T. urartu was the A-genome donor of hexaploid wheat.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0322-3) contains supplementary material, which is available to authorized users.

Molecular evolution of Wcor15 gene enhanced our understanding of the origin of A, B and D genomes in Triticum aestivum

“…Compared to the Wcor15-2A2 sequence, the Wcor15-2A1 sequence showed much higher identity (100%) with the Wcor15-2A sequences from tetraploid and hexaploid wheats, suggesting that the T. urartu might be the direct donor of the Wcor15-2A in common wheat and that Wcor15-2A gene from A genome has no mutation during two sequential allopolyploidization events from T. urartu to tetraploid and hexaploid wheats. The result is consistency with the previous studies 23 24 52 . However, taking into consideration of no amplicon from T. monococcum and T. boeoticum when using Wcor15A primer, it suggested that non-coding regions of Wcor15-2A1 were obviously different from Wcor15-2A2 .…”

“…The study on origin of A, B and D genomes of bread wheat has been a hot topic. Understanding the origin of hexaploid wheat would benefit not only the genetic diversity but also expand the genetic basis for wheat breeding 23 42 . Previous studies have demonstrated that the sequence data of conserved gene can be used to study the evolution of gene families from different species 43 44 45 .…”

“…The A u and A m genomes have similar genome size and gene content 22 . T. urartu , the wild diploid wheat from the Fertile Crescent region, has long been considered as the A-genome donor to tetraploid and hexaploid wheat species 23 24 . In polyploid wheat, the origin of the B genome is still under debating, in spite of a large number of attempts to identify the parental species 24 .…”

Molecular detection of glutenin and gliadin genes in the domesticated and wild relatives of wheat using allele-specific markers

“…Also, T. urartu, as A-genome donor of common wheat, carried two new alleles Glu-3A.3c and Glu-3A.3d. In the present study, the number of allelic variants exceeded that found by Zhang et al (2013) in common wheat, or by Wang et al (2010), Ahmadpoor et al (2014), Ahmadi and Pour-Aboughadareh (2015), Luo et al (2015) and Cuesta et al (2017) in wild relatives of wheat. The development of allele-specific markers is based on the polymorphisms of nucleotide sequences among different alleles, and the relationship between markers and phenotypes needs to be established.…”

Allelic analysis of low molecular weight glutenin subunits using 2-DGE in Korean wheat cultivars

“…Additionally, some alleles are not reliably distinguished by this method. 2-DGE in which proteins are separated according to isoelectric point (pI) and molecular mass (MW) has been used to distinguish many but not all LMW-GS alleles and the increased resolution of 2-DGE has resulted in the identification of new alleles not observed by SDS-PAGE ( Ikeda et al 2006 , Lee et al 2016 , Liu et al 2010 , Luo et al 2015 , Zhang et al 2012 , Zhen et al 2014 ). PCR is a much simpler technique and primers specific for many alleles at the Glu-A3 and Glu-B3 loci have been developed and are currently used in breeding programs ( Wang et al 2009 , 2010 , Zhang et al 2004 , 2012 , Zhao et al 2006 ).…”