The Ploidy Genetic Manipulation And Karyotype Analysis Of Radish (Raphanus Sativus L.)

Radish (Raphanus sativus L.) is an important vegetable that originated in China, and the germplasm resources are very abundant. The microspore culture of radish can obtain homozygous plants and shorten breeding time; polyploidy breeding can improve crop quality; the karyotype analysis can obtain cytological basis. But at present the frequency of embryogenesis of radish microspore culture is low, efficient induction system of tetraploid has not been established, and there isn't systematic report about radish karyotype.In this study we researched the factors that affecting embryogenesis of radish, induced tetraploid by 3 methods and investigated karyotypes of 11 radish germplasm by a root-tip squashing method in order to provide information for haploid breeding, tetraploid breeding and germplasm identification in radish.We have invegested microspore culture using our laboratory materials to select the genotypes that could form embryoids and studied various factors that affecting mictrospore culture. The experiments showed:There were 19 genotypes that formed various developmental stages embryoids, of which a material "Wanhong" formed cotyledon-shaped embryoid; When the bud length was 3-4mm, most of the microspores were late uninucleated microspores and the length of the anthers was equal to or slightly longer than the petals; When each dish contained 5～10 buds, the density could be 1～2×105/ml; At the inisial time using NLN-17 media and then adjusting to NLN-13 after heat shock treatment was beneficial to embryogenesis; In the heat-shock treatment period, culturing microspores in NLN-13 media containing 50～500 mg/L colchicines could effectively promote embryogenesis.Using three methods to induce autotetraploid plants, and identified. The results showed that the growth potential of the plants that using soaking seeds treatment was weak, and the plant mortality was high and we didn't abtain autotetraploid plants; The best effect of autotraploid was abtained with 0.1% colchicine treatment when treating apical portion of cotyledon; The highest available tetraploid induction rate was 31.25% when soaking the apical of cotyledon of duanyel3 in 0.1% colchicines solution.In order to obtain precise cyto-genetic data in radish, we have investigated karyotypes of 11 radish accessions by a root-tip squashing method. The results showed that all the accessions were diploid (2n=18); the karyotype was mainly consisted of metacentric and submetacentric chromosomes, satellite was found in three germplasms.The karyotype type belonged to 1A or 2A, and the relative length of chromosome varies from 8.16% to 14.19%. The asymmetry index was between 55.39% and 59.48%, indicating that there was relative similarity of karyotype among the germplasms. At the same time the 11 germplasm was identified using RAPD and SRAP molecular markers. The results showed that the same skin color radishes were mostly clustered into a class, whereas Nau-tjwq, Nau-dzh2 and Nau-qyh which had satellites didn't cluster together with their same color radish, indicating that satellite has an important role in the germplasm distinction.