2-DIMENSIONAL ELECTROPHORESIS OF PROTEINS AS A SOURCE OF MONOGENIC AND CODOMINANT MARKERS FOR POPULATION-GENETICS AND MAPPING THE EXPRESSEDGENOME

The positional polymorphism of polypeptides revealed using two-dimensi onal polyacrylamide gel electrophoresis (2-D PAGE) was analysed in seg regating families of four plant species, a gymnosperm (maritime pine), and three angiosperms (maize, barley and pea). All of the 170 variati ons scored had monogenic and codominant inheritance, making 2-D PAGE a quite abundant and cheap source of good-quality genetic markers. Gene tic 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 marker s for chromosomal regions previously lacking molecular markers. In the context of the genome mapping projects, such markers are physiologica lly relevant in that they reveal loci whose transcripts are translated in the organ analysed.