Abstract:

【Objective】 The objective of this study was to reveal the molecular characteristics of LMW-GS genes at Glu-A3 locus in different wheat cultivars, and to find candidate genes with potential value in wheat quality improvement. 【Method】 Chinese wheat cultivars Xiaoyan 6, Shaanyou 225, and Australian bread wheat cultivars Suneca and Cook, as well as Chinese Spring were selected as materials to clone and characterize LMW-GS genes at Glu-A3 locus with the specific primer by PCR in this investigation. 【Result】 Five LMW-GSgenes at Glu-A3 locus were cloned, named as CookGlu-A3 (accession number EU871816), XYGlu-A3 (FJ876820), SYGlu-A3 (FJ876819), SunecaGlu-A3 (FJ876822), CSGlu-A3 (FJ876821). All of them contained the entire coding regions, 197 bp of promoter sequences and 51 bp downstream sequences after stop codons. The differences among the five genes were that there existed some SNPs and insertions/deletions. All the deduced proteins of the five genes belong to LMW-i type. Notablely, the deduced protein of CookGlu-A3 contained 7 cysteine residues, with a 38 aa fragment in the C-terminal domain including the 7th conserved Cys residue missing. On the basis of the similarity of coding sequence, 51 known LMW-GS genes were classified into three groups, and each group was corresponding to a specific locus Glu-A3, Glu-B3 or Glu-D3, respectively. 【Conclusion】 CookGlu-A3 encoded a LMW-i type glutenin subunit with 7 cysteine residues, and it may be a novel LMW-GS gene. All LMW-GS genes at different chromosomal locations had their own specific characteristics in their coding sequences. The coding sequences of the LMW-GS genes at locus Glu-A3 had less identity with those at locus Glu-B3 or Glu-D3.

Key words: wheat, low molecular weight glutenin subunit, Glu-A3 locus