Identification For The Tolerance To Bolting And Cloning Of Related Genes In Radish

Radish (Raphanus sativus L.) is one of the most important vegetables in China. The time of boltingor flowering is important for radish product and breeding. It is useful to identify the bolting tolerancegermplasm and gain insight into the mechanism of bolting and flowering. In this study, typical radishinbred lines were selected to evaluate the bolting tolerance and to screen molecular markers. Fragmentsof main genes in flowering pathways including FLC、FRI and LFY were cloned and analyzed. The mainresults are as followed:1. The seeds of73radish inbreed lines were treated at4for21d and sowed in the greenhouse toevaluate their bolting tolerance.9foreign materials were still unbolting after growing for136d, whichwere classified into the high tolerance to bolting materials. Among them,7accessions were R. sativus L.var. longipinnatus Bailey originated from Korea (6) and Japan (1) respectively,1Japanese accessionbelonged to R. sativus L. var. niger,1Russian accession belonged to R. sativus L. var. radicola Pers.7indexes were chosen to evaluate bolting characteristics of64bolting accessions. Frequency distributionof all indexes accorded with normal distribution. Significance analysis showed that7indexes among64accessions were all at highly significant level, indicating that bolting features of tested accessionesexpressed significant difference. Correlation analysis resulted that budding date and flowering date wereclosely related (0.92), and both of them could be selected to effectively evaluate the bolting tolerance ofradish germplasm. Bolting speed reached a highly significant correlation level with stem height atflowering stage, stem height at budding stage and number of bolting days. Principal component analysisand subordinate function method were selected to evaluate the tolerance to bolting, radish accessionswere well clustered into different groups related with their tolerance to bolting, especially2accessionswith highly tolerance to bolting.2.64radish accessions were analyzed by11pairs of SSR primers related with flowering genesinquired from RadishBase. The results of5pairs of SSR markers showed polymorphism loci and that ofUN03188-1reached a very significant correlation with bolting date and flowering date.8molecularmarkers reported from radish and related species were selected to evaluate34radish accessions whichhad different bolting features. The results showed that only1InDel and1SCAR marker could amplifytarget band, but not related with their tolerance to bolting.3. One cDNA sequence encoding FLC was cloned from YR and oil radish respectively. Sequencealignment showed that there were15base differences, which caused8amino acid differences. Both ofthem contained a MADS-box conservative structure domain (17th-78th), and2amino acids (68th and70th) within conservative domain structure were different. The differences of formula and theoreticalisoelectric point between YR and oil radish were obvious. FLC transcription factor coding region ofradish, cabbage and Chinese cabbage were very conservative, the similarity was96.13%. Two DNAsequences of FRI and LFY were cloned from YR and oil radish and alignment result showed theirsequences were the same. Sequence analysis showed that FRI and LFY contained mitochondria leadingpeptide. Phylogenetic analysis showed that predicted amino acids of FRI and LFY in radish were closed to Brassica. The similarities of the closest sequence with cloned radish genes were80.17%(Brassicanapus, H6VVI6) and55.17%(Radish, B7XD70) respectively.