Homoeologous recombination within bread wheat to develop novel combinations of HMW-GS genes: transfer of the Glu-A1 locus to chromosome 1D

In an attempt to improve the bread-making quality within hexaploid wheat by elaborating novel high-molecular weight glutenin subunits (HMW-GS) combinations useful in wheat-breeding programmes, a 1A chromosome fragment carrying the Glu-A1 locus encoding the subunit Ax2*, was translocated to the long arm of chromosome 1D. The partially isohomoeoallelic line, designated RR239, had a meiotic behaviour as regular as cv. Courtot. It was characterised using genomic in situ hybridization and microsatellite markers as well as biochemical and proteomic approaches. The translocated 1D chromosome had an interstitial 1AL segment representing in average 30% of the recombinant arm length that was confirmed by molecular analysis. The genetic length of the removed segment in chromosome 1DL was estimated to be at least 51 cM, and that of the interstitial 1AL translocation to be at least 33 cM. Proteome analysis performed on total endosperm proteins revealed variation in amounts, 8 spots and 1 spot being up- and downregulated, respectively. Quantitative variations in HMW-GS were observed for the Glu-A1 (Ax2*) and Glu-B1 (Bx7 + By8) loci in response to duplication of the Glu-A1 locus.