Studies On Pre-Selection Of Cold-resistant/Dwarf Rootstock And Relevant Molecular Markers Of Dwarf Character In Pear

Dwarf dense planting has been become a trend and indication for fruit tree products in the world. Selection of variety and rootstock of dwarfish and cold resistance in pear, not only can boost industry of pear tree, but also can adapt cultivation condition for producing in north region. In this study, F₁ progeny of S₂ hybrids were used as material, we constructed S₂×Chaoxianyangli genetic linkage map and screen the markers possible related with dwarf character by using RAPD technique, and meanwhile physiological index were determined. It can provide a certain theoretical foundation for selecting dwarf /cold-resistant varieties in pear. the result are as follows:Five hybrid combinations of F₁ progeny of S₂ were no significant diffence in height. hybrid progenies crossed with S₂×Shanli was the best cold-resistant, and was less in combination of S₂×Nanguoli. It was shown that significant positive correlation between leaf stoma density and height/cold-resistance. The lower was in stoma density of leaf, the shorter in height, but, the stronger in cold-resistant. The ratio of round water/free water was higher, the old-resistance was stronger. Oil the contrary, lower ratio of round water/free water with weaker cold-resistance. Eight pear plants were screened which were cold-resistance and dwarfism by the result of physiology index.Segregation patterns in S₂×Chaoxianyangli F₁ progeny by using RAPD marker were divided into three types: The markers accorded with Mendelian segregation were 51, occupied 38.1%; Deviated from Mendelian segregation markers were 13, the ratio was 9.7%; Abnomoral segregation markers were three, the proportion was 2.2%. It can be yielded 2.2 available mapping markers by each primer bewteen Medelian sergregation and deviated from Medelian segregation (64 bands) which accorded with 1:1 or 3:1 pattern, can be used to construct parents and F₁ progeny genetic linkage map.There were fifteen linkage groups in this map of S₂×Chaoxianyangli using RAPD marker, including seven distorted markers and thirty-two Mendelian markers, it covered 394.18 cM, and the average distance was 10.11 cM . One RAPD marker (S67-1837) was acquired which may be linked with dwarf character by utilizing 135 primers, which was located in fist linkage map after JoinMap@3.0 analysis.The specific fragment was sequenced, the results indicated: The length of the fragment was 1873bp. We designed a pair of specific primer according to the result of sequencing. Then amplified in F₁ progenies of S₂ hybrid and varieties of pear by using of this primer, but the specific of S67-1873 were disappeared, the reason will be studied furthermore in the future.