A comparison of methods for extraction and separation of hordein fractions from 29 barley varieties

Methods have been developed for extracting and comparing the hordein fractions of barley seed as a means of identifying different varieties. A rapid method involving a single extraction with 55% (v/v) propan‐2‐ol+2% (v/v) 2‐mercaptoethanol at 60°C removed slightly less nitrogen from milled grain than a more detailed procedure in which three sequential extractions were made with the same solvent. The hordein fractions extracted by these two procedures were alkylated and their component poly‐peptides separated by four one‐dimensional and two two‐dimensional systems. The results showed that the hordein extracted by both techniques had the same polypeptide composition and thus the rapid method was satisfactory for use in comparing varieties. Sodium dodecyl sulphate‐polyacrylamide gel electrophoresis and isoelectric focusing were used to compare the polypeptide composition of the hordein fractions from 29 varieties. Using the former system a total of 11 different patterns were recognised while further small differences between several varieties were revealed by isoelectric focusing or two‐dimensional analysis. If the polypeptide patterns obtained by these techniques are considered in conjunction with other grain characters it should be possible to identify almost all of the 29 varieties.