| Sweet cherry (P. avium L) as a kind of fruit tree is planted in great area and its fruit is early ripe. The self-incompatibility of sweet cherry is the important factor affecting the production. Most of varieties are unknown the S-genotypes, so identification of the S-genotypes is very important for choosing the pollinators, breeding parents, studying the molecular mechanism of SI and breeding self-compatible varieties. Chinese cherry (P. pseudocerasus L.) has very important resource properties, such as self-compatibility, short development period of fruit and compact type which are all of significant value for breeding self-compatible excellent varieties. Our study mainly utilized the methods such as S gene specific PCR techenique, identification of fruit setting percentage in field and isoelectric focusing to clone the S genes of sweet cherry of which S genotypes are unknown, to identify the variety's S genotype, to study the mechanism of sweet cherry's self-incompatibility and Chinese cherry's self-compatibility. As the result, by using leaf genomic DNA we set up the technique system which could identify the S genotypes based on the length of amplified bands in S gene specific PCR. The main results are as follows:1. We designed a pair of specific primers PruC2 and PruC4R based on the very conserved nucleic acid region C2 and RC4 of rosaceous S gene to do S gene specific PCR on leaf genomic DNA, cloned and sequenced the amplified bands of S genes and compared the sequences on GeneBank. It was proved that the same length of amplified bands was the same kind of S gene. The lengths of S gene amplified bands were that S1 was 676-677bp, S3was 761-762bp, S4was 943-944bp, S6was 456bp respectively. The sequences and lengths of S gene amplified bands were made clear for the first time.2.We set up the technique system to identify the S genotypes of unknown genotype's varieties by using the PruC2 and PruC4R specific primers to do specific PCR on genomic DNA based on the lengths of amplified bands. We identified the S genotypes of mainly planted varieties, for example 'Hongdeng' 'Early ruby' 'Hongyan' and 'Van' all were S1S3 'Jueze' 'Napoleon' 'Hongfeng' and 'Waiyin 7' all were S3S4; 'Black tartarin' was S1S6; 'Changbahong ' was S1S4 and 'Elton' was S3S6.3. The fruit setting percentage showed that the varieties with the same kind of S genotype could not be used as pollinators for each other because the hybridizing between them cross-incompatible; the varieties of different S genotypes cross-compatible; the kinds of S genes in compatible pollens didn't affect the fruit setting percentage.4. By analyzing the S genotypes of planted varieties we found that the occuringfrequency of S genes were different. It was showed that the frequency of S3 was the highest for 42.31%; the frequencies of S1 and S4 were the secondary for 23.08% and 26.92%; the frequency of S6 was lower for 7.69%; S2 and S5 didn't occur0 For this reason we called S3 the high frequency S gene, S1 and S4 the middle frequency S gene, S6 lower frequency S gene, S2 and S5 the low frequency S gene.5. We divided the tested cherry varieties into 8 types by using RAPD analysis. The varieties in the same kind type had the same kind of S gene or the S genotype because of the heredity of S gene. But most of the varieties in distant relationship each other had the same high frequency S3 gene not only due to genetic reason likely due to S3 having the advantage of selection in breeding.6.The self-pollination and cross-pollination tests on the sweet varieties, for example, 'Jueze', 'Early ruby' 'Elton' et al. showed that the growth of compatible and incompatible pollen tubes had no difference during 24-3 Oh after pollination, and they all could germinate and arrive at the top and middle part of style. But the growth of them had obvious difference during 48-77h after pollination, it was observed that the compatible pollen tubes could arrive at ovary but the incompatible pollen tubes could arrive at the middle and base part of style and the g... |
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