Identification Of Self-incompatibility Genotype In Sweet Cherry (Prunus Avium) By AS-PCR Technology

In order to assure genetic variability, many flowering plants have evolved strategies to prevent inbreeding and promote out-crosses. The predominant form of self-incompatibility (SI) is the Gametophytic self-incompatibility (GSI) system , in which the compatibility of a cross is determined by the haploid genome of the pollen and the diploid genome of the pistil. Sweet cherry exhibits the monofactorial gametophytic self-incompatibility system similar to other self-incompatible fruit tree species of the Rosaceae. Therefore, they will not set fruit unless pollinated with cultivars with different S-genotypes. Determination of correct pollen incompatibility groups and assignment of cultivars to the groups are essential for good crop production. Pollen incompatibility groups in sweet cherry have been identified by controlled pollination tests and/or pollen tube growth tests, but these tests is time-consuming and prone to be affected by environmental factors. The allele-specific PCR system was established to identify the S-genotype of 61 sweet cherry cultivars in this study.Recently SFBs (S-haplotype specific F-box protein gene) were found to associate with pollen determinant of GSI. This report identified the SFB4 'of the self-compatible S4' haplotype, and the SFB4' gene-specific molecular marker was established.All results were summarized as follows:1. The PCR based identification technology of 7 known self-incompatibility alleles of sweet cherry was established .Two pairs of consensus primers BFP73/74 and BFP93/94 were designed from published cDNA sequences of 57 to S6 S-RNase to reveal length variation of the first and the second introns.With the consensus and allele-Specific primers of S1 and 55, most sweet cherry varities S-genotype can be visualized directly on an agarose gel. The use of the consensus and allele-specific primers was demonstrated by detecting genotypes that have been published recently. This method is a rapid and convenient technique that can be used on vegetative material.2. The allele-specific PCR system was used to identify the S-genotype of 61 sweet cherry cultivars. We genotyped some main Chinese sweet cherry cultivars for the first time using the alleles specific PCR, The new listing of cultivars S-allele assignments was presented and proved to be an effective reference for selecting pollinator and pre-selection the new selections for breeders and growers.3. This report identified the SFB4' of the self-compatible S4' haplotype. The alignment of the sequences of SFB4' and SFB4 by the BLAST program revealed that there is a 4 bp deletion in SFB4' — — TTTA. The sequence polymorphism generated by the 'TTTA' deletion in the SFB4' was exploited to develop the SFB4 'gene-specific molecular marker specific for the detection of the S4' haplotype but not S4 haplotype. The SFB4' gene-specific molecular marker can be visualized directly on an agarose gel, so it can be immediately applied to a marker-assistant cherry breeding program.4. It was known that the self-compatible sweet cherry cultivar 'Stella' has the genotype S3S4'. Using the AS-PCR, we analysed progeny from selfing 'Stella' and detected three genotypes: S3S4', S4'S4', S3S3, respectively. S4'S4' and S3S4' segregated approximately 1:1.27 in the seedlings, and the genotype of S3S3 is 2.08%. The S4 'S4' homozygous germplasm is very valuable in the breeding of SC sweet cherry cultivars.