Reexamination of self-incompatibility genotypes in the Japanese pears: 'Choju', 'Kimizukawase', 'Meigetsu', and 'Ichiharawase'

Self - incompatibility genotypes (S-genotype) were reexamined in the Japane se pear 'Choju', 'Kimizukawase', 'Meigetsu', and 'Ichiharawase'. The S-geno types of the former 2 cultivars are designated as S2S5, whereas those of th e latter 2 cultivars are S1S5. 'Choju' and 'Kimizukawase', which are cross-incompatible in both directions , possessed the S-1 - and S-5 - allele associated proteins (S-protein) in t heir styles. PCR (polymerase chain reaction) amplifications of self - incom patibility genes (S - gene) also revealed the presence of S-1 - and S-5 - g ene fragments in both cultivars. Thus, the S-genotypes of 'Choju' and 'Kimi zukawase' were confirmed to be S1S5, but not S2S5. 'Meigetsu' and 'Ichiharawase' were compatible with 'Choju'; their styles co ntained the SI-protein but not the S-5-protein. PCR amplification also sugg ested the absence of S-5-gene in both cultivars. These results together wit h those in the literature on the appearance of Fl individuals with pollen c ross - incompatibility with 'Meigetsu' indicate that the S-genotypes of 'Me igetsu' and 'Ichiharawase' are S1S7 or S1Sx (S-x indicates an allele other than S-1 to S-7).