GENETIC ANALYSIS OF THE HOR-3 LOCUS AND CHARACTERIZATION OF ITS PRODUCTS IN BARLEY (HORDEUM VULGARE, L.).

摘要

The genes encoding the major storage proteins (hordeins) of barley have been previously designated the Hor loci. Two Hor loci, Hor-1 and Hor-2, have been mapped to the short arm of barley chromosome 5, approximately 10-15 centimorgans apart. A third Hor locus, Hor-3 is described and has been determined to lie approximately 30 centimorgans toward the centromere from the Hor-1 locus by recombination analysis.;The near 100,000 molecular weight glutelins of wheat have been implicated in bread wheat baking quality. While there may be significant differences between D hordein of barley and these wheat proteins, no obviously important differences were discovered by this study which could explain the lack of dough strength in barley.;A method for the purification of microgram quantities of D hordein is described. The stability of D hordein to extensive reduction is assessed and the amino acid composition of D hordein from the barley varieties 'Advance', 'Bomi' and 'Hiproly' determined. A glutelin of wheat with similar molecular weight and pI was purified from the variety 'Peak 72'. These four proteins were then subjected to peptide mapping using cyanogen bromide, DPCC-trypsin, chymotrypsin and Staphylococcus aureus V8 protease. Cyanogen bromide failed to cleave within the proteins, while trypsin and chymotrypsin cleaved the proteins into fragments too small to effectively resolve by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Staphylococcus aureus V8 protease cleaved the proteins into a few fragments ranging in apparent molecular weights from 15,000 to 30,000. The conservation of cleavage sites within the proteins indicates the extreme similarity of these proteins.