IDENTIFICATION OF RAPD MARKERS LINKED TO THE LOCI CONTROLLING ERUCIC-ACID LEVEL IN RAPESEED

The recent development of the industrial use of rapeseed oil rich in e rucic acid has led to increased interest in the improvement of the hig h-erucic-acid (50-60%) varieties and to research towards genotypes con taining a very high erucic acid content. This trait is controlled by t wo genes with additive effects. The low-erucic-acid trait was relative ly easily introduced through backcrosses into various backgrounds beca use the zero-erucic-acid homozygotes were clearly identified in the se gregating populations. To select for high erucic acid level is more di fficult because of the partial overlap of the high-erucic-acid homozyg ous class and the intermediate one, containing heterozygotes. In order to help conventional breeding, RAPD markers were used to map the two genes involved in determining the erucic acid content in a doubled hap loid progeny derived from a 'low x high' erucic acid F1 hybrid. The tw o genes were successfully localized in two independent linkage groups, through a QTL approach. A close association was found between individ ual plant genotypes and the erucic acid content of the doubled haploid progeny, and it was shown that the two genes do not contribute unifor mly to the C22:1 level. The value of molecular gene mapping of such a trait in a conventional breeding programme is discussed.