DETECTION AND CHARACTERIZATION OF A GLUTENIN SUBUNIT WITH UNUSUAL HIGH MR AT THE GLU-A1 LOCUS IN HEXAPLOID WHEAT

A hexaploid wheat landrace collected from the Baluchistan province of Pakistan was found to possess a novel high-molecular-weight glutenin s ubunit (HMW-GS). The subunit has a very slow electrophoretic mobility as revealed by SDS-PAGE, and its molecular weight is comparable to tha t of the highest molecular weight glutenin subunit (''2.2'' encoded in the D-genome) reported so far in hexaploid wheat varieties and landra ces of Japanese origin. Evidence obtained from (PCR) gene amplificatio n studies using the primers specific for Glu-1 loci proved that the ge ne coding for this novel subunit belongs to the Glu-A1 locus located o n the long arm of chromosome 1A. Digestion of the amplified gene (PCR product) with restriction enzymes indicated that the novel gene differ s from prevailing Glu-A1 alleles (null, 1 and 2) by an extra DNA frag ment of approximately 600 base pairs. The results also indicated that the novel subunit is most probably a derivative of subunit 2 that has very likely incorporated the 600-bp fragment following a process of u nequal crossing over. The present findings were further substantiated by reserved phase high performance liquid chromatography (RP-HPLC) ana lysis.