| China is one of the native origins of Pyrus. The history of pear cultivating has been thousands of years. New cultivars has been increasing by selection, breeding and tissue culture. 43 pear cultivars including 20 new pear hybrids and their parents were studied by fluorescent AFLP. A fingerprinting has been constructed. Relationship and inheritance between hybrids and parents have been analyzed and 20 new cultivars have been classified on molecular level. The purpose is to provide basis for pear classification and theoretical reference for parents selection when hybridization is carried out.1. Different time of leaf picking for DNA extraction was studied. Tender leaves from branches cultivated by water has high antioxidation, contain less impurities and get more genetic DNA. The cultivation is simple and there will be no time limit for leaf picking.2. 7 primer combinations with high polymorphism were selected from 64 primer combinations. 784 bands were amplified totally among 43 cultivars, in which 699 bands were polymorphic and the polymorphic percentage is 89.2%. M6/E2 amplified 145 bands, which is the most while the lest is 83 bands amplified by M2/E7. The average is 112 bands amplified by each combination.3. An AFLP fingerprinting of 43 pears was constructed. Any primer combination can identify all the cultivars and the efficiency is 100%. 68 characteristic bands were amplified. M6/E2 amplified the most (17 bands) but M7/E2 amplified the lest (just 2 bands). There were 29 cultivars have characteristic bands, which was 67.4% among all of the cultivars.4. All the cultivars clustered 4 groups which were Pyrus pyrifolia Nakai, Pyrus ussuriensis Maxim., Pyrus bretschneideri Rehd. and Pyrus communis L.. Cultivars with the same parents clustered closely.5. 20 new cultivars were classified 3 types which were mother-tended type, father-tended type and deviated type.6. 20 new cultivars were classified on molecular level and most of the results were consisted with traditional calssification.7. 'Shenbuzhi' was inferred to be a cultivar of deviated type or one of its parents may be Pyrus bretschneideri Rehd.. 'Pingguoli' was thought to be a cultivar of Pyrus bretschneideri Rehd. but contain blood relationship from Pyrus pyrifolia Nakai and Pyrus ussuriensis Maxim.. 'Kuerlexiangli' was thought to be a cultivar of Pyrus bretschneideri Rehd., too, but have blood relationship from Pyrus communis L.. |
