Open Access Research article

Tetraploid and hexaploid wheat varieties reveal large differences in expression of alpha-gliadins from homoeologous Gli-2 loci

Elma MJ Salentijn1*, Svetlana V Goryunova2, Noor Bas3, Ingrid M van der Meer1, Hetty C van den Broeck1, Thomas Bastien1, Luud JWJ Gilissen14 and Marinus JM Smulders14

Author Affiliations

1 Plant Research International, Wageningen UR, P.O. Box 16, NL-6700 AA Wageningen, the Netherlands

2 Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991, Russia

3 CGN, P.O. Box 16, NL-6700 AA Wageningen, The Netherlands

4 Allergy Consortium Wageningen, P.O. Box 16, NL-6700 AA Wageningen, the Netherlands

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BMC Genomics 2009, 10:48  doi:10.1186/1471-2164-10-48

Published: 26 January 2009



Α-gliadins form a multigene protein family encoded by multiple α-gliadin (Gli-2) genes at three genomic loci, Gli-A2, Gli-B2 and Gli-D2, respectively located on the homoeologous wheat chromosomes 6AS, 6BS, and 6DS. These proteins contain a number of important celiac disease (CD)-immunogenic domains. The α-gliadins expressed from the Gli-B2 locus harbour fewer conserved CD-epitopes than those from Gli-A2, whereas the Gli-D2 gliadins have the highest CD-immunogenic potential. In order to detect differences in the highly CD-immunogenic α-gliadin fraction we determined the relative expression level from the homoeologous Gli-2 loci in various tetraploid and hexaploid wheat genotypes by using a quantitative pyrosequencing method and by analyzing expressed sequence tag (EST) sequences.


We detected large differences in relative expression levels of α-gliadin genes from the three homoeologous loci among wheat genotypes, both as relative numbers of expressed sequence tag (EST) sequences from specific varieties and when using a quantitative pyrosequencing assay specific for Gli-A2 genes. The relative Gli-A2 expression level in a tetraploid durum wheat cultivar ('Probstdorfer Pandur') was 41%. In genotypes derived from landraces, the Gli-A2 frequency varied between 12% and 58%. In some advanced hexaploid bread wheat cultivars the genes from locus Gli-B2 were hardly expressed (e.g., less than 5% in 'Lavett') but in others they made up more than 40% (e.g., in 'Baldus').


Here, we have shown that large differences exist in relative expression levels of α-gliadins from the homoeologous Gli-2 loci among wheat genotypes. Since the homoelogous genes differ in the amount of conserved CD-epitopes, screening for differential expression from the homoeologous Gli-2 loci can be employed for the pre-selection of wheat varieties in the search for varieties with very low CD-immunogenic potential. Pyrosequencing is a method that can be employed for such a 'gene family-specific quantitative transcriptome profiling'.