The Genetic Character Of Self-incompatibility And Application In Breeding For Sweet Cherry (Prunus Avium L.)

Gametophytic self-incompatibility (GSI) is a widespread mechanism in flowering plants, which prevents self-fertilization and promotes outcrossing . Sweet cherry exhibits the monofactorial gametophytic self-incompatibility systerm similar to other self-incompatible fruit tree species of the Rosaceae. Genetic studies have been focusing on the SI of flowering plants, but the research was seldom done about the application of the SI in the creating new germplasm. Prunus avium, Prunus ceruasus, Cerasus tomentosa were used in our study. All results were summarized as follows:1. Based on conserved regions of Prunus S ribonucleases ( S-RNase ) AS PCR primers were designed, and the allele-specific PCR system was established to identify the S-genotype of 57 sweet cherry cultivars. We genotyped some main Chinese sweet cherry cultivars for the first time using the alleles specific PCR, and two new S genotype (S1S6, S4S9) were found, which made the listing of S-allele assignment more completed. The new listing of cultivar 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.2. 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 patterns :one with two bands like 'Stella' and the other two with a single band. We interpret these as S3S4', S4'S4', S3S3 respectively. S4'S4' and S3S4' segregated approximately 1:1.27 in the 325 seedlings, and the genotype of S3S3 is 2.16%. The S4'S4' homozygous germplasm is very valuable in the breeding of SC sweet cherry cultivars.3. Distant crossing is an efficient way in breeding the new sweet cherry cultivars and the advanced stocks . It is difficult to get the seedlings because of the low germination capacity of the hybrid. We did interspecificcross 'Van' with Cerasus tomentosa and used embryonic culture to overcome the incompatibility of species and genus. We named the interspecifichybrid germplasm 'G3'. AS-PCR and RAPD were used to identify the genetic relationship of G3 with its parents. The two methods got the consistent conclusion.4. The result of interspecific crosses between sweet and sour cherry demonstrated that GSI existed in sour cherry. By comparing sweet cherry with sour cherry S-allele function in pollen cross test suggested that the S1 and S4 RNases from Favoriate were able to recognize and inhibit the S1 and S4 pollen from Rainer. AS-PCR was really a useful method to analysis the kinship of sour cherry, sweet cherry and Prunus fruticosa.5. In self-compatibility cultivars S-protein had no inhibition to self-pollen germination and growth at a lower concentration, while it showed a little inhibiting at a higher concentration. But in self-incompatibility cultivars, self-style protein had significant inhibition to self-pollen germination and growth, and the inhibition increased with the enhancing of the protein concentration.6.By investigating the effect of different temperature and S genotype to the breakdown of self-incompatibility , we found the S3S4 genotypes always had the highest breakdown rate at all genotype and at 25 癈 the breakdown rate were highest in all the temperature treatments.