Molecular characterization of S-RNase genes and S-genotypes in the Japanese apricot (Prunus mume Sieb. et Zucc.)

Three partial S-RNase genes, MSRN-1, MSRN-2, and MSRN-3, in the Japanese ap ricot (Prunus mume Sieb. et Zucc.) were isolated from the three cultivars N ankou, Gyokuei, and Kairyouuchidaume, respectively. The structural characte ristics revealed that S-RNase genes from the Japanese apricot were in the T 2/SRNase-type S-RNase family with five conserved regions (C1, C2, C3, RC4, and C5) and one variable region (RHV) as reported in the other rosaceous pl ants. In the phylogenetic tree of T2/S SRNase-type RNases, three SRNase gen es of the Japanese apricot did not form a species-specific subgroup but the Prunus subfamily did. At least seven S-allelic genes were present in the J apanese apricot, and S-genotypes of six representative cultivars, including Nankou, Gyokuei, Kairyouuchidaume, Baigou, Kagajizou, and Oushuku were fir st established in this study as S1S7, S2S6, S3S4, S3S6, S3S6 and S1S5-, res pectively. An extended elucidation of the S-genotype would contribute to a more efficient breeding program of the Japanese apricot.