Study On Transfer Of Fungi-resistant Gene Into Cucumber

Cucumber plays an important role in vegetable supply,but it was suffered from many kinds of Fungi easily,which can decrease its yield and deteriorate its quality. Traditional method of breeding has many disadvantages,such as long period,huge investment and low efficiency..lt is also restricted to the shortage of resistant genes.There is devolution of resistance in resistant cultivar.Cucumber exist serious hamper of sexual hybridization,.So it is difficult to obtain the superior cultivar with high resistance. This study established a highly efficient regeneration system of cucumber and then transfer the fungi-resistant gene(bean chitinase gene)into cucumber,which mediated by Agrobacteriwn tumefaciens.This has not been studied in previous reports in China.The integration of target gene into cucumber genome was analyzed.The factors influencing regeneration rate and transformation rate were discussed.The result was summarized as follows:I Effect of explants and genetypes on organgenisis The best explant was cotyledonaiy nodes;The optimum shoot inducing medium is MS-I-6-BA lmglL;Significant differences in the capacity of regeneration were observed among the genetypes. The cultivar hang Chun Mi Ciad the highest frequency of regeneration(93.2%),the second was e San40.l%),the lowest was ao Lai Shao?l 0.6%).2 Effect of Suc. Concentration on somatic embryogenisis A relatively high sucrose concentrations in the initiation medium promoted greater frequencies of somatic embryogenesis.The suitable sucrose concentration was 9% in initiation medium;3 Effect of genetypes and PGR on somatic embtyogenisis Genetypes had a significant effect on the frequency of somatic embryogenesis.The cultivar e Sanad the highest rate of embryo formation,up to 67. l%,yet few embryos were observed in hang Chun Mi Cind ao Lai ShaoPlant growth regulators in embryo induction medium also had effect on embryos formation.NAA 0.5mgIL and 6-BA 0.5mg/L was the suitable combination.4 The optimum precedure in cucumber transformation as follows:The cotyledonary nodes was precultured for 1-2 days,infected 5 mm in vacuum vessel,co-cultivatecl in medium including 6-BA lmg/L and AS l00~.miol/L, pH 5.2.The optimum concentration of kanamycin used in resistant shoots selection was 3OmgIL.5 Detection of transforming regenerated cucumber Two pairs of primer was used to do PCR respectively. 50 of 88 regenerated plants of擟hang Chun Mi Ci攚ere positive and the percentage is 56.82%,the positive rate calculated with the number of infected explants was 3.84%.1 0 of 14 regenerated plants of 揧e San攚ere positive,the percentage is 71.43%, the positive rate calculated with the number of infected explants was 3.090/o.The results of PCR demonstrated the integration of target gene into cucumber genome primarily.Postgraduate:Hou AijuSupervisor:Prof Zhu YanmingMajor: Botany...