| Self-incompatibility is an important mechanism which could prevent close breeding and keep species continuity, it existed widely in the plant kingdom. Apple exhibits gametophytic self-incompatibility(GSI). GSI was controlled by a single, multi-allelic locus, the S-locus. In production, we must allocated the pollen donor which had different S genotype or chose the manual assistance pollination with apple pollen of different S genotypes to keep the yield and quality. There exited blindness of allocation the pollen donor if we didn't know the S genotype of the cultivars. Therefore, it was an important to identify the S genotype of apple cultivar quickly and early. Apple cultivars of KORIN, Nanfangcui , USA-8, Huaguan ,Matsumoto Nishiki and Dounan were introduced recently by Hebei province, but their S genotype were unknown. In this thesis, S genotype of some apple cultivars were studied, so as to provide theory and practice basis for apple production and cultivation. The results were as follows:1. The improved method of genomic DNA extraction was as follows (1) Adding extract (0. 4mol/L glucose, 3% PVP, 1% β -mercaptoethanol)prior to lysis the nuclei and to inhibit the formation of oxidized polyphenol components.(2) Using frozen anhydrous ethyl alcohol instead of isopropyl alcohol which was used generally to deposit DNA and to inhibit salts and carbohydrate etc deposition altogether with DNA, this could save time of DNA deposition and raise the efficiency. (3) Only using chloroform and 3 -Methyl- 1-butanol to accelerate layering between organic and inorganic , reducing the pollution of phenol .(4) Centrifugal method of low speed was used in the collection of DNA, comparing to hooking DNA, this method could avoide making machinery injury to DNA (5) Dissolved DNA with sterile distilled water which had advantage to sequencing. A260/A280 of genomic DNA was 1.8-1.9 and the concentration of genomic DNA was about 2.54μg/μL using the method of improved CTAB. A260/A280 of genomic DNA was 1.3-1.7, and concentration of genomic DNA was lower than 0.21μg/μL using the general CTAB method than improved CTAB method. DNA showed a trim bright band without smear, and there was no residue bright in sample hole when detected with 0.8% agarose gel eletrophoresis. The result show that genomic DNA is complete and without degradation.2. The A260/A280 ratio of genomic DNA was 1.8~1.9 with improved CTAB method with material of tender leaf on the top of shoots and ageing leaf, all of the genomic DNA purity was high, but the genomic DNA concentration of ageing leaf was lower 0.17μg/μL thanthat of tender leaf. Therefore, the extraction of genomic DNA should be with tender leaf on the top of shoot.3. There weren't notable influence of the samples which were fresh, put into — 70 °C refrigerator and put into — 40 °C refrigerator for a month to the quantity and quality of genomic DNA. The extraction of genomic DNA was degradation when samples were put into—30°C refrigerator for a month, and the genomic DNA turned brown to some extento4. A pair of apple primers (Pi:5' - TTTACGCAGCAATATCAG - 3';P2:5' -ACGTTCGGCCAAATA/cATT—3') were designed according to the conserved sequence of amino acid and S genotype Si-, S2-, S3-, S5-, S7-, S9-, Sg, S24-, S26-, S27-and S30- were amplified with this pair of apple primers, this showed that the primers were able to amplify apple S-alleles, with high S-allele specificity.5. After PCR amplification, the cultivars of Nanfangcui , Huaguan ,KORIN, Matsumoto Nishiki and USA-8 contain a 340bp segment, KORIN contain a 530bp segment, USA-8 contain a 1300bp segment.The results show that Self-incompatibility alleles were isolated and identified by PCR-RFLP analysis, and their self-incompatibility genotype were S9S27 , S1S9, S9S9 , S2S9 , S2S9 respectively.6. S allele of Dounan was not identified with specific restriction enzymes of Si- ,S2- ,S3- ,S4-,S5- ,S7- ,S9- ,S!0- ,S20- ,S25- ,S26- ,S27- ,S3o- after sequence, the result showed that this part contain 348bp,the result of BLAST in NCBI showed that the identity was above 80%, The BLAST between S2-Allele and S33-Allele was 97.5% (did not contain intron),but did not identified with specific restriction enzymes of S2, therefore, this part was defined for a new S-allele, the accepted number in Genbank was DQ219464.7. Pollens of Golden Delicious, Fuji and Gala were pollinated to Dounan in the field, the pollination result showed that the fruit set percentage of inflorescence were 33% , 68%and 74% respectively, the fruit set percentage of flower were 34% , 64% and 77%respectively. The result of semi vitro culture of style pollinated with the same cultivars showed that the rate of styles with pollen tube through their bottoms were 38.46% , 70.83% and 86.67%respectively, the number of pollen tubes per style were 1.15,3.54 and 2.83, the result showed that pollination combinations among Dounan and Golden Delicious, Fuji, Gala were compatible , Dounan did not contain the S gene of Si,S2,S3, Ss,S9 ,and this result was accordant with PCR-RFLP.
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