| Ipomoea batatas L. (Lam.), one important type of food crops. It was found out that virus diseases were harm to its quality and output. Obtained virus-free plants by means of meristem tip culture was the available solution to deal with the problem. Furthermore, the improvement in quality has become the most important target in sweetpotato breeding all over the world since 1980s, especially the improvement in content and composition of protein. Some factors effect on virus elimination of Ipomoea batatas L. (Lam.) by stem tip culture and several diagnostic methods for detecting virus diseases were studied. The 10kD Zein gene, regulated by sporamin promotor, was introduced into sweetpotato. The expression level of 1 OkD Zein gene in organ, protein accumulation pattern and the regulation of sporamin promoter were analysis. The major agro-characters and foreign gene effect on internal gene expression also-were studied in this paper. The research work and results were reported as following: 1 Establishment of virus-free sweetpotato breeding systemObtained virus-free plants by meristem tip culture, some factors, including origination of buds, genotype and hormone, affecting on the rates of plant regeneration were studied. And the result showed that: The ability of division and differentiation of tips affected the rates of plant regeneration, and the highest frequency of plant regeneration come from the tip witch sprouted directly form tuber, and reached 53.2%. genotype, such as YvSu303 and "NanRuiShao" ,the frequency reached18.0% and 12.0% each, both were higher than "NanShu88"(4.4%)and "YanShu5"(2.0%). And hormone also influenced on the frequency, NAA could improve the rate and made it reach 27.41%. Some plants were detected by symptomatology, indicator plants, NCM-ELISA and RT-PCR, and found that sweetpotato ofChongQing was mainly infected by Sweetpotato feather mottled virus (SPFMV) and Sweetpotato latent virus (SPVMV). Variance analysis showed that virus influenced more significant on the length of stem and petiole and the number of links. Virus-free plants were 63.16% longer than control and grow better in liquid medium than solid.2 optimization of in vitro genetic transformation systemWith the best suitable in vitro plant regeneration system, Test material was superior cultivars of Sweetpotato, and the Agrobacterium. tumefaciens strain was N9-l (carry GUS and NPT-II gene). Effect of Kanamycin (Kan) and Cefazolin Sodium(Cef) on the adventitious bud differentiation of Sweetpotato explants were studied, as well as the Influence of concentration of bacterium solution and infected time, pre-culture and co-culture time, methyi a -naphthyl acetate (NAA), silver nitrate (AgNO3) and acetosyringone (AS) on transformation rateand the optimization of in vitro genetic transformation system by Agrobacterium-mediated were studied.The results suggested that the differentiation of explants were affected by Kan, when the concentration of Kan higher than 80mgL-1, the differentiation of adventitious buds was inhibited, therefore 80mgL-1 Kan was used as selection stress for obtaining the kanamycin-resistant (Kanr)buds. Furthermore, The concentration of Cef was 500 mgL-1, the propagation of bacterial was restrained and the frequency of adventitious buds would be decrease rapidly. So the concentration of Cef for inhibiting growth of bacterium would be 500 mgL-1.The result from observation and experiment suggested that some no-transformation adventitious roots and buds were dead after selected 3 times on the select medium if the concentration of Agrobacterium. tumefaciens was lower(OD600=0.2), even the infected time lasted 6 minutes. The infect explants would be wholly covered by bacterium solution and result in explants browning and dying when the solution concentration was higher(OD6oo= 0.8) even the infect time was 2 minutes. When the concentration of bacterium solution was OD600=0.4 and the infected time lasted about 4 minutes, the production rates of Kanr buds were highest, reached 26.4%. Therefore, OD600=0.4 an... |
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