GENETIC AND BIOCHEMICAL-CHARACTERIZATION OF NOVEL LOW-MOLECULAR-WEIGHT GLUTENIN SUBUNITS IN WHEAT (TRITICUM-AESTIVUM L)

Two novel low molecular weight subunits of glutenin with relative mole cular mass (M-r values) of 30 and 32 kDa were isolated from the seeds of hexaploid wheat and characterized at genetic and biochemical levels . Among 115 Indian bread wheat cultivars analysed, 40 had a narrow dou blet of the new protein bands, 69 had a wide doublet, 3 had only the f aster moving band of the doublet, and the remaining 3 cultivars had on ly the slower moving band. These subunits could be seen in the alkylat ed glutenin preparations only and the genes for the faster (designated Glu-D4) and slower (designated Glu-D5) moving protein bands of the do ublet were located on chromosomes 1D and 7D, respectively. Amino acid composition of the two new subunits was quite different from those of the other well-characterized gluten proteins, as the new subunits have lower amounts of proline and relatively higher amounts of glycine, as partic acid - asparagine, cysteine, and lysine. Polyclonal antibodies raised against these polypeptides cross-reacted strongly with the majo r low molecular weight subunits of wheat glutenin (Glu-3 subunits), bu t did not cross-react with the high molecular weight glutenin subunits or monomeric gliadins. Furthermore, preliminary results on the N-term inal amino acid sequences of the new subunits show homology with the m ajor low molecular weight glutenin subunits, suggesting an evolutionar y link between the two.