EXPRESSION OF THE S-LOCUS RECEPTOR KINASE MULTIGENE FAMILY IN BRASSICA-OLERACEA

The S-receptor kinase (SRK) gene which is implicated in the self-incompatibility system of Brassica oleracea is one member of a large and complex family of similar sequences. Genomic and cDNA clones were isolated for the authentic, S-linked SRK(29) gene and its DNA sequence determined. Reverse transcriptase PCR (RT-PCR) was used to detect the expression of SRK(29) and other members of the family in stigma, leaf and root tissues. The SRK was found to be stigma-specific whereas, for instance, K3 transcripts appeared in all three tissues. The RT-PCR analysis also demonstrated the existence of partially processed intermediates for several of the kinase transcripts and, in the case of SRK(29), a product apparently resulting from the splicing of a cryptic intron. RFLP analysis of an F-2 family segregating for the S-29 allele was used to show S-linkage for the SRK and possibly for the K2 sequence. The K8 kinase probe also revealed a minor RFLP which segregated with the S-locus.