Molecular Characterization Of Different Triticum Monococcum Ssp. Monococcum Glu-Alx Alleles

High-molecular-weight glutenin subunits (HMW-GSs) are important seed storage proteins associated with bread-making quality in common wheat (Triticum aestivum L.,2n = 6x= 42; AABBDD). Variation in the Glu-Alx locus in common wheat is scare. Diploid Triticum monococcum ssp. monococcum (2n= 2x=14; AmAm) is the first cultivated wheat. In the present study, allelic variations at the Glu-Alx locus were systematically investigated in 197 T. monococcum ssp. monococcum accessions. The results are as follows:Out of the 10 detected Glu-Alx alleles,7 were novel, including Glu-A1md, Glu-Ame, Glu-A1mf, Glu-A1mg, Glu-Amh,Glu-A1mi, and Glu-A1mj. The frequency and distribution of the 10 alleles was highly variable, with the lowest for Glu-A1mg (one accession,0.5%) and the highest for Glu-A1mc (132 accessions,67%). Glu-A1ma, which was found in two accessions, was silent, and the remainding alleles were active. The predominant allele Glu-A1mc showed mobility similar to 1 Ax2*.Two pairs of primers were further used to amplify both ends of the Glu-Alx gene. The first pair produced one amplicon (fragment 1), which included the signal peptide, the N-terminal domain, and the first 174 nucleotides of the repetitive domain. The second pair produced one amplicon (fragment 2), which included the last 210 nucleotides of the repetitive domain and the C-terminal domain. Sequencing analysis indicated that fragment 1 was 477 bp, whereas fragment 2 was 336 bp; both fragments were the same size in all sequences. These combined sequences (fragment 1+fragment 2) were deposited in the GenBank database.DNA polymorphism was further evaluated using the concatenated sequence of fragments 1 and 2. Eighteen polymorphic sites were detected in the sequences, including 10 from fragment 1 and 8 from fragment 2. Of these mutations,5 were synonymous, whereas the other 13 were non-synonymous, including 6 in the repetitive domain. The C-terminal domain (four mutations) had more variations than the N-terminal domain (two mutations).The deduced proteins were aligned with those of Axl and Ax2* subunits in wheat. Besides single nucleotide polymorphisms (SNPs), there were differences in the presence of three deletion/insertions in the repetitive domain, one in fragment 1 (137-142 residues, Pro-Gly-Gln-Gly-Gln-Gln) and two in fragment 2 (6-10 residues; Gln-Gly-Gln-Gln-Glyl; 46-50 residues, Ser-Gly-Gln-Gly-Gln). These variations might affect the elastic properties of wheat flour.New variations in T. monococcum occurred after the divergence between A and Am. Therefore, these variations do not occur in common wheat populations. These allelic variations could be used as novel resources to further improve wheat quality.