The S haplotypes lacking SLG in the genome of Brassica rapa

Self-incompatibility (SI) discriminating self-and non-self pollen is regulated by S-locus genes in Brassica. In most of the S haplotypes, a highly polymorphic S-locus glycoprotein (SLG) gene is tightly linked to genes for the SI determinants, S-receptor kinase (SRK) and SPII, although the precise function of SLG in SI has not been clarified. In the present study, we performed DNA gel blot analysis for S³², S³³, and S³⁶ haplotypes of Brassica rapa showing normal SI phenotypes and concluded that there might be no SLG in their genome. RNA gel blot analysis of the SLG-less S haplotypes indicated the possible existence of eSRK transcripts in the stigma. These three S haplotypes are useful resources to discern the molecular mechanism of the SI reaction without SLG.