Comparison of low molecular weight glutenin subunits identified by SDS-PAGE, 2-DE, MALDI-TOF-MS and PCR in common wheat
Background Low-molecular-weight glutenin subunits (LMW-GS) play a crucial role in determining end-use quality of common wheat by influencing the viscoelastic properties of dough. Four different methods - sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2-DE, IEF × SDS-PAGE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and polymerase chain reaction (PCR), were used to characterize the LMW-GS composition in 103 cultivars from 12 countries. Results At theGlu-A3locus, all seven alleles could be reliably identified by 2-DE and PCR. However, the allelesGlu-A3eandGlu-A3dcould not be routinely distinguished fromGlu-A3fandGlu-A3g, respectively, based on SDS-PAGE, and the alleleGlu-A3acould not be differentiated fromGlu-A3cby MALDI-TOF-MS. At theGlu-B3locus, allelesGlu-B3a,Glu-B3b,Glu-B3c,Glu-B3g,Glu-B3handGlu-B3jcould be clearly identified by all four methods, whereasGlu-B3ab,Glu-B3ac,Glu-B3adcould only be identified by the 2-DE method. At theGlu-D3locus, allelic identification was problematic for the electrophoresis based methods and PCR. MALDI-TOF-MS has the potential to reliably identify theGlu-D3alleles. Conclusions PCR is the simplest, most accurate, lowest cost, and therefore recommended method for identification ofGlu-A3andGlu-B3alleles in breeding programs. A combination of methods was required to identify certain alleles, and would be especially useful when characterizing new alleles. A standard set of 30 cultivars for use in future studies was chosen to represent all LMW-GS allelic variants in the collection. Among them, Chinese Spring, Opata 85, Seri 82 and Pavon 76 were recommended as a core set for use in SDS-PAGE gels.Glu-D3candGlu-D3eare the same allele. Two new alleles, namely,Glu-D3min cultivar Darius, andGlu-D3nin Fengmai 27, were identified by 2-DE. Utilization of the suggested standard cultivar set, seed of which is available from the CIMMYT and INRA Clermont-Ferrand germplasm collections, should also promote information sharing in the identification of individual LMW-GS and thus provide useful information for quality improvement in common wheat.