SFBs of Japanese plum (Prunus salicina): Cloning seven alleles and determining their linkage to the S-RNase gene

Japanese plum (Prunus salicina Lindl.), a species of the Rosaceae family, carries the S-RNase-mediated gametophytic self-incompatibility system. Self-incompatibility is manifested if the 5-haplotype of the pollen is carried also by the pollinated flower. Thus, for fertilization to occur, the cultivars have to be genetically compatible. The haplotype is conferred by an 5-locus, which contains the style-specific expressed S-RNase and the pollen-specific expressed F-box genes (SFB). Since both the S-RNase and the SFB genes are multiallelic and are characteristic of each of the S-haplotypes, they are ideal markers for molecular 5-typing. In this work, seven SFBs, from eight Japanese plum cultivars, were cloned and sequenced. Five of the alleles were published recently and two SFB^g and SFB^k are new. The physical linkage of SFB^b and SFB^c to their adjacent S-RNase was determined; it is 544 base pairs (bp) and 404 bp for the S^b and S^c loci, respectively.