Variety identification in maize lines via capillary electrophoresis of zeins in isoelectric acidic buffers

Zeins (the prolamins or seed storage proteins in maize) have been used to characterize and identify different genotypes. Zeins were fractionated by capillary zone electrophoresis in acidic, amphoteric buffers, which represent a medium of moderate conductivity and are thus compatible with higher voltage gradients. The running buffer consisted of 40 mM isoelectric aspartic acid, in presence of 6 M urea and 0.5% hydroxyethyl cellulose (apparent pH: 3.8; pI in the absence of urea: 2.77). Thirty-one different zein peaks were mapped out of a total of 21 different maize genotypes. Each of them typically exhibited seven to twelve peaks, with some genotypes showing up to 20 zein bands. Due to slightly changing elution times, caused by a lack of reproducibility of the electroendoosmotic flow in uncoated silica surfaces, correct peak assignment and alignment among different runs was obtained by multivariate statistical analysis. The present method compares well, both in resolution and total number of peaks, with current protocols adopted for screening of maize inbreds, which consist of isoelectric focusing in agarose gels