BREEDING OF HOMOZYGOTES OF SELF-INCOMPATIBLE HAPLOTYPE IN JAPANESE PEAR (PYRUS PYRIFOLIA NAKAI)

Homozygotes of self-incompatible haplotypes are useful tools for identifying the S-genotype. So far, we have selected S₂, S₃ and S₄^sm homozygotes. The objective of this study is to select S₄, S₅ and S₇ homozygotes in Japanese pear. ‘421-6’ and ‘421-24’, which were selected from among seedlings obtained from the selfing of ‘Shinsui’ (S₄S₅), are compatible with the pollen of ‘Shinsui’. Pollen of ‘421-6’ is incompatible with ‘Yakumo’ (S₁S₄) and ‘Gold Nijisseiki’ (S₂S₄), but compatible with ‘Housui’ (S₃S₅). On the other hand, the pollen of ‘421-24’ is incompatible with ‘Housui’ and ‘Okusankichi’ (S₅S₇), but compatible with ‘Yakumo’ (S₁S₄). ‘420-50’, which was selected from among the selfed seedlings of ‘Okusankichi’, is compatible with the pollen of ‘Okusankichi’. Pollen of ‘420-50’ is incompatible with ‘Hougetsu’ (S₁S₇), but compatible with ‘Housui’. The PCR-RFLP method showed only one S-RNase fragment in these three lines; that of ‘421-6’ is digested by NdeI, that of ‘421-24’ is digested by AlwNI and that of ‘420-50’ is digested by AccII. These results suggest that the S-genotypes of ‘421-6’, ‘421-24’ and ‘420-50’ are S₄S₄, S₅S₅ and S₇S₇, respectively.