Two-dimensional electrophoresis of proteins as a source of monogenic and codominant markers for population genetics and mapping the expressed genome

The positional polymorphism of polypeptides revealed using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was analysed in segregating families of four plant species, a gymnosperm (maritime pine), and three angiosperms (maize, barley and pea). All of the 170 variations scored had monogenic and codominant inheritance, making 2-D PAGE a quite abundant and cheap source of good-quality genetic markers. Genetic mapping showed that the loci involved are well distributed on the chromosomes. In particular, the construction of a composite map of the maize genome including 253 markers revealed that the protein loci are interspersed with the RFLP loci, and provide in some instances markers for chromosomal regions previously lacking molecular markers. In the context of the genome mapping projects, such markers are physiologically relevant in that they reveal loci whose transcripts are translated in the organ analysed.