Reconsideration of S-genotype for a Japanese Pear 'Kumoi'

A Japanese pear 'Kumoi' was previously determined as S3S4 by pollination tests, but its S-genotype was reconsidered following our PCR-RFLP (S1 to S9) analyses and pollination tests. Based on its compatibility with 'Seigyoku' (S3S4), and PCR-RFLP analysis, 'Kumoi' was classified as S1S3 for the first time. Additional pollination tests were necessary to prove our contention, but 'Kumoi' did not supply sufficient flowers. 'Sekaiichi' was also assigned as S1S3 by PCR-RFLP analysis, and incompatibility with 'Kumoi'. Instead of 'Kumoi', 'Sekaiichi' was pollinated with the pollen from an 55-homozygote and that from an Ssm4-homozygote. The lack of fruit set revealed that 'Sekaiichi' was incompatible with the S3 and Ssm4 pollen, leading us to predict that the 5-genotype of 'Sekaiichi' was S1S3 or 8384. Two S-genotypes with S1S3 and S2S3 segregated in hybrid progenies between 'Doitsu' (S1S2) and 'Sekaiichi', indicating that S1 was present in 'Sekaiichi'. These results of pollination tests with 'Sekaiichi' indicated the S-genotype of 'Kumoi' was S1S3.