Study of the allelic diversity of the Glu-1 genes in the durum wheat (Triticum durum Desf.) collection

Durum wheat grain, which is used in the production of pasta and groats, must meet requirements for specific parameters of gluten quality. Its high quality depends on various factors, including the allelic state of the high-molecular-weight glutenin genes that encode subunits of wheat storage proteins (HMW-GS). This work presents, for the first time, the allelic structure of the Glu-1 loci in a wide collection of facultative durum wheat varieties and breeding lines. The objective of this study was to identify the allelic state of the Glu-A1 and Glu-B1 genes which encode high-molecular-weight glutenins in this collection. Additionally, the study aimed to evaluate the impact of these genes on the gluten index. The material for the research consisted of a collection of 198 breeding lines and varieties of facultative durum wheat obtained from the Lukyanenko National Grain Center. The allelic state of HMW-GS was assessed using SDS-PAGE. The gluten index value was measured using the Perten Glutomatic® 2100 System (PerkinElmer, USA). To identify allelic variants of HMW-GS genes, KASP markers were also used. The Glu-Ax1/x2*_SNP marker was utilized to identify the alleles of Glu-A1 . The BX7OE_866_SNP marker was employed to differentiate between the Glu-B1b (Bx7 + By8) and Glu-B1al (Bx7OE + By8) alleles, which cannot be distinguished through SDS-PAGE. The BX7OE_866_SNP marker is based on a single nucleotide polymorphism (SNP) in the promoter region: the C variant is associated with the Glu-B1al allele, which carries a duplicated copy of the Bx7 locus, while the G variant is associated with the absence of the Bx7 duplication. The allelic state of the Glu-A1 and Glu-B1 was identified by comparing the results obtained using the KASP and SDS-PAGE assays. According to the research results, three alleles were identified for Glu-A1 , and eight alleles were identified for Glu-B1 . The vast majority of the studied accessions contained the Glu-A1c allele (98 %), while the proportion of accessions with Glu-A1a and Glu-A1b accounted for 0.5 % and 1.5 %, respectively. For Glu-B1 , there was a higher number of accessions with the Glu-B1al allele (60 %) compared to accessions carrying Glu-B1d (17 %) and Glu-B1e (12 %). The accessions containing subunits Bx7 + By8 ( Glu-B1b ) accounted for 3 % of the collection. In addition, rare alleles Glu-B1h (1 %), Glu-B1i (1 %), as well as Glu-B1z (1 %) and Glu-B1z* (5 %) were identified. The last two differed in a single nucleotide polymorphism in the promoter region of the gene that encodes the Bx7 subunit. There was a tendency towards the distribution and fixation of the Glu-B1z* allele in durum wheat varieties. A positive effect of Glu-B1d on the gluten index and a negative effect of Glu-B1e on its value were also observed.