Research Of Semi-dwarf Peach's SSR Markers And Leaves Microstructure

Peach is the third major deciduous fruit trees in China. Labor cost increases with the development of economy, and easy management of fruit tree has become one of the developmental directions for fruit tree cultivation.Because of the lack of good semi-dwarf germplasm resources,the suitable peach species for the production and simplified management are very scarcely. SD9238 is a semi-dwarf (limited dwarf) mutant which is discovered in the breeding nursery by WANG Zhi-qiang etc.. Initial genetic evaluation shows that the semi-dwarf trait is controlled by a pair of alleles, and the semi-dwarf is dominant opposed to the conventional type , which is the ideal genetic resource to regulate peach growth and achieve the semi-dwarf tree.Further study is helpful to achieve the improved orientation of fruit-related traits, thus solving a series of difficulties in the peach industry, such as difficult manage, high cutting employment and high production cost etc.. The F1 segregation population, total of 141 seedlings derived from the cross of'Qinglang'(standard type)×'Zhong Youtao 14'(semi-dwarf type), was tested for identifying of SSR markers linked to peach semi-dwarf gene.The compared anatomical structures of leaf blades of'Zhong Youtao 14'and'Qinglang'in different parts which at branch top and branch-base were studyed by paraffin section method.Results are as follows:1. Conventional CTAB DNA extraction was improved. Improved CTAB method used twice DNA precipitation method in the extraction process, which reduced the impurities, purified the samples, and laid a solid foundation for the precise development of the follow-up tests.2. Due to the analysis of the various factors in a multi-level through the design of orthogonal reaction, the optimized SSR mixture of 20μl was obtained: 5mmol/L Mg²⁺ 1.5μl,2.5mM/L dNTPs 2μl,5U Taq DNA polymerase 0.22μl, 10xBuffer 4μl, 0.6μl of each 10mM primer, 20ng template 0.8μl.3. One SSR marker, CPDCT23, was found to be linked with semi-dwarf gene. CPDCT23 primers amplified bands in the progenies of the test results meet the law of semi-dwarf and normal separation. The marker is dominant on standard type, and recessive on the semi-dwarf type. Further analysis showed that the marker could be used for semi-dwarf trait identifying with correct rate of 92.0% and difference fragment size is about 305 bp.4. The thickness of leaf'Zhongyou 14'is thicker than that of'Qinglang'in the corresponding parts; the palisade tissue thickness of'Zhongyou 14'is thicker than that of'Qinglang'in the corresponding parts;the thickness of leaf base and middle leaf at branch top is thicker than that of branch base in two specises.