TABLE 4.

Number of nonfunctional S-haplotypes and the SI or SC phenotypes for 92 sour cherry seedlings

No. of nonfunctional S-haplotypes in each Seedling	No. of seedlings analyzed	Phenotype of seedlings
		No. SI	No. SC
1	17	17	0
2	17	3a	14
3	37	0	37
4	21	0	21

^aThree progeny with S-genotype S₄S₆S_aS_d were determined to be SI, despite having two nonfunctional S-haplotypes. Partial S-RNase and SFB sequences from the S_a- and S_d- haplotypes are identical (N. R. Hauck, unpublished results), suggesting that the S_a and S_d represent different mutations of a common S-haplotype. We are currently testing the possibility that S_a has a functional S-RNase and a nonfunctional SFB, whereas S_d has a nonfunctional S-RNase and a functional SFB. In this case, S₄S₆S_aS_d individuals would be predicted to be SI under the one-allele-match model since S_aS_d pollen would be rejected due to a match between a functional S_a-RNase and SFB_d.