Biochemical and molecular characterisation of Glu-1 loci in Argentinean wheat cultivars.

Abstract

The high molecular weight glutenin subunit (HMW-GS) composition of a collection of 107 Argentinean bread wheat cultivars was analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Allelic variation at the Glu-1 loci was identified and its frequency calculated. Eleven alleles were detected, three encoded at the Glu-A1 locus, six at the Glu-B1 locus and two at the Glu-D1 locus. A low frequency of the null allele at the Glu-A1 locus and a high frequency of subunits 5+10 at the Glu-D1 locus were observed. Reversed phase-high performance liquid chromatography (RP-HPLC) analysis was used to further characterise HMW-GS. Two different types of Bx subunit 8 (named subunits 8 and 8*) were detected, the latter having shorter elution time. Subunit 8* was not identifiable by SDS-PAGE. According to quantification by RP-HPLC analysis, two groups of subunit 7 were observed. One group, with a relatively high proportion of subunit 7 (approximately 39% of the total amount of HMW-GS) appeared in cultivars with allele 7+8* at the Glu-B1 locus; a second group of subunit 7 (around 24% of the total amount of HMW-GS), was found in alleles 7+8, 7+8* and 7+9. Restriction fragment length polymorphisms (RFLP) analyses of HMW-GS genes were also carried out after digestion of genomic DNA with HindIII and TaqI restriction enzymes. The relationship between DNA fragment size and glutenin subunits, as estimated by electrophoretic mobility in SDS-PAGE, was also examined. The restriction enzyme TaqI demonstrated to be a useful tool to detect homozygous plants in selection programs against the Glu-A1 null allele.