Plant & Animal Genome VI Conference

P36

A RARE WHEAT LMW GLUTENIN

Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, Manitoba, Canada R3T 2M9

Wheat cultivar Glenlea is characterized by the its extra gluten strength. Its protein composition has been studied extensively. A low molecular weight (LMW) glutenin subunit called band 50 was found in Glenlea. More than 160 lines and cultivars of wheat were assessed by SDS-PAGE for their LMW glutenin composition and only 5 cultivars unrelated to Glenlea possessed LMW glutenin band 50. The gene coding for band 50 was cloned from Glenlea and sequenced. Perfect co-segregation was shown for a doubled haploid population of 72 plants. The expected size of the protein is 42,7 KDa which correspond to one of the largest LMW glutenin subunit. The gene was mapped to chromosome 1A. The deduced amino acid sequence reveals a truncated N-terminal that does not contain the expected cysteine residue in position 5. However, an extra cysteine residue was found at position 217. This extra cysteine residue is located inside a tight loop formed by an intra-molecular Cys-Cys bond. This peculiar structure and its implication in gluten strength as well as the origin of this protein will be discussed.