USE OF IMMUNOCHEMICAL AND SSCP ANALYSES TO TEST HOMOZYGOSITY AT THE S-LOCUS OF BRASSICA-OLERACEA GENOTYPES

The self-incompatibility reaction of cruciferous plants prevents self- fertilization and has been shown to be controlled by at least two gene s situated at a single multiallelic locus, the S locus. One of these t wo genes, the S locus glycoprotein (SLG) gene, encodes an abundant gly coprotein secreted to the cell wall of stigma papillae. Identification of tho se S alleles present at the S locus is of prime interest when studying the self-incompatibility response and can be achieved by iden tifying the SLG of the stigma. Here, we show that using anti-SLG antib odies in an immunochemical analysis, combined with a SSCP (single-stra nd conformation polymorphism) approach to characterize the correspondi ng stigma-specific, SLG mRNA, allowed the identification of plants het erogeneous at the S locus among populations of plants that were though t to be homozygous for known SLG alleles. This analysis stresses the i mportance of testing the homozygosity at the S locus of lines consider ed inbred for a known S allele as mix-up of seeds may occur during the breeding programme.