Three nonfunctional S-haplotypes in self-compatible tetraploid Chinese cherry (Prunus pseudocerasus L. cv. Taixiaohongying)

In tetraploid sour cherry (Prunus cerasus L.), the accumulation of nonfunctional S-haplotypes with disrupted pistil-component (stylar-S) and/or pollen-component (pollen-S) function leads to a genotype-dependent loss of gametophytic self-incompatibility (GSI). Tetraploid Chinese cherry (Prunus pseudocerasus L.) exhibits self-compatibility. In this study, we characterized four S-haplotype-specific F-box protein genes (SFBs) from pollen cDNA of Chinese cherry cv. 'Taixiaohongying' with the S-genotype S (1) S (2) S (3) S (4) . Of the four SFBs, three showed typical characteristics of SFBs from other Prunus species and functioned as SFB genes; these were termed SFB (a) (GQ395341), SFB (b) (GQ395340), and SFB (c) (EU267943), respectively. The fourth SFB, termed SFB (d) (GQ395339), has a 100-bp deletion that resulted in the transcript for SFB (d) lacking the F-box domain. SFB (d) lost the pollen-S specific function and functioned as the SFB gene mutant. The results of reverse transcription-PCR analysis indicated that the four SFB genes were transcribed at approximately the same intensity.