ANALYSIS OF NEAR FLANKING DNAS OF GENES WITHIN COMPLEX WHEAT LOCI: COMPARING HOMOEOLGOUS REGIONS CONTAINING ORTHOLGOUS AND PARALOGOUS GENES

USDA ARS, Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710-1105 USA

We have investigated the flanking regions of numerous members of the hexaploid wheat (Triticum aestivum) seed storage protein gene families, including the complete high-molecular-weight (HMW) glutenin gene set and members of the gliadin superfamily. The analysis has included the x-and y-type paralogous HMW-glutenin genes, and the orthologous genes within these two types. Sequence differences among orthologous genes may be indicating early steps in homologous region divergence. Comparisons of near flanking sequences suggests wheat storage protein gene sequences are contained within approximately 600-1200 bp upstream of the start codon and 200-400 bp downstream of the stop codon. In addition to comparing near flanking DNAs among these genes, we have obtained over 70 kb of DNA outside the coding and presumed promoter sequences. Although too limited in extent for firm conclusions, this additional DNA is suggesting the wheat intergenic contains less frequent nested-transposon tracts that thus far reported in maize, and more similar to the pattern recently reported for barley. Most of the wheat flanking DNAs has no matches in sequence databases except for a few remanents of transposons. Also found are few new classes of MITEs and short sequences of unknown function associated with non-related wheat genes.