Techniques of Stem Tip Culture and Virus Detection of New Sweet Potato Varieties

In order to optimize the culture method of the stem tips of sweet potato, and obtain the virus-free test-tube plantlet of the new sweet potato variety, the effects of NAA, GA₃ and 6-BA on the differentiation of stem tips and plant regeneration of sweet potato were studied by orthogonal experiment, and then the best formula of the medium was selected. Based on the orthogonal experiment, the differentiation of stem tips and plant regeneration of different sweet potato varieties in the optimal combination of medium were further investigated, and the method of RT-PCR was used to detect the virus diseases (SPFMV, SPCSV, SPVG, SPVC and SPLV) in the regenerated lines of sweet potato varieties after they became seedling. The results showed that the effects of various experimental factors on the differentiation of stem tips and plant regeneration of Fushu 604 were ordered as follows: 6-BA, NAA and GA₃. The optimal medium combination for the stem-tip tissue culture seedling of Fushu 604 was MS medium +6-BA 1.2 mg·L^-1+NAA 0.10 mg·L^-1+GA₃ 0.1 mg·L^-1. The germination rate and seedling rate of the stem-tip tissue culture seedling were 93.3% and 50.0%, respectively. Different varieties of sweet potato showed different differentiation of stem tips under the optimal medium combination, among which the varieties of Fucaishu 23 and Fushu 116 showed the best differentiation of stem tips and plant regeneration. The test-tube plantlets of different varieties of sweet potato were detected by RT-PCR, and then 12 virus-free test-tube plantlets of sweet potato were obtained, including Fushu No.8, Fushu 34, Fucaishu 22, Fushu 916, Fushu 90, Fucaishu 23, Fushu 116, Fushu 317, Fushu 604, Fushu No.16, Fushu 33 and Fushu 113, which could be used in the actual production.