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 c haracterize and identify different genotypes. Zeins were fractionated by ca pillary zone electrophoresis in acidic, amphoteric buffers, which represent a medium of moderate conductivity and are thus compatible with higher volt age gradients. The running buffer consisted of 40 mM isoelectric aspartic a cid, in presence of 6 M urea and 0.5% hydroxyethyl cellulose (apparent pH: 3.8; pl 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 typica lly exhibited seven to twelve peaks, with some genotypes showing up to 20 z ein bands. Due to slightly changing elution times, caused by a lack of repr oducibility of the electroendoosmotic flow in uncoated silica surfaces, cor rect peak assignment and alignment among different runs was obtained by mul tivariate statistical analysis. The present method compares well, both in r esolution and total number of peaks, with current protocols adopted for scr eening of maize inbreds, which consist of isoelectric focusing in agarose g els.