In Vitro Screening Of Fusarium Oxysporum Toxin-Resistant Mutants And Transfromation With Chitinase Gene In Sweetpotato

Explants from leaf blades of sweet potato meristem culture plantlets from four varieties, Xinzhonghua,, Jingshan25, Jingshan57, and Xiayin No.1, were placed on MS basic medium supplemented with different hormone composition, The medium for the highest efficiency regeneration was selected for these varieties, respectively. Furthermore, effects of different parts of leaf blades and supplementing with various level ABA or AgNO3 on regeneration were studied. The high efficiency regeneration systems for four varieties, Xinzhonghua, Jingshan25, Jingshan57, Xiayin No 1. were established, respectively. These were as follows: explants were obtained from the base of leaf blades and contained the mid-rib segment and petiole cut end. MS medium containing NAA 2mg/L, 6BA 0.lmg/L and AgNO3 2mgIL, was used for induction of callus and shoot regeneration for Xinzhonghua and Xiayin NO. I regeneration time was 90 days. Callus was induced on MS medium containing. KT 0.5mgIL, 2,4-D 0.Smg/L, and AgNO3 2mgIL, and then transformed to hormone-free MS medium for shoot formation, regeneration time last sixty days for Jingshan25. For Jingsha57, callus was induced on MS medium containing NAA 2mg/L, 6BA 0.1 mg/L and AgNO3 2mg/L, and then transformed to MS medium contained IAA 0.Smg/L, KT 0.Smg/L, and AgNO3 2mg/L for shoot formation, regeneration time last 90 days. The plant regeneration frequencies for the four varieties were from 70% to 86%. Compared on pathogenicity between the crude toxin extracts from fusarium oxysponus and the spore suspension, the results showed that the crude toxin can be used to identify resistance to stem-rot and the toxicity of the crude toxin decreased by hump-heat sterilization. Killing concentration of the crude toxin on callus, root, and was 20%, 15%, 10%, respectively. Compared on screening efficiency by adding the crude toxin into medium between in stage of callus formation and in all stage of culture. The results showed that the differentiate ability of callus lost when selection was carried at the stage of induction of callus, no shoot was generated from the callus. But under three different selection conditions, toxin resistance variant plants were obtained. Frequency of toxin-resistant plant was 12.3-26.5% averagely. VI D CZZj XinZhonghua was best resistant improving variety by utilization of the method and three mutants lines from the variety were middle resistant to sweet potato stem rot disease under field condition by using artificial inoculation. On the base, three mutant lines were used for RAPD analysis, the results showed that DNA polymorphism existed between the control and three mutant lines, and their genomic similarity is form98.5% to99.5%. We had developed a system to induce important agricultural characteristics into sweet potato using Agrobacerium tumefacins mediated transformation. Sensitivity of sweet potato leaf tissue to the antibiotics Kanamycin, carbenieillin and cefotaximine were studied. The presence of 75 mg/L kanamycin inhibited callus formation from leaf blade explants. Root and shoot formations were inhibited by kanamycin at 5OmgIL and 3Omg/L, respectively. Carbenicillin added at 300mgIL and cefotaximine added at 250mg/L was suitable for both preventing growth of bacteria and formatting...