The Construction Of Genetic Linkage Map In A3 Chromosome In Brassica Napus

In this research, based on the DH population with 182 lines derived from the No.2127-17and Zhongyou821, the new SSR markers of Brassica napus were exploited,a genetic linkage map of Brassica napus in A3 chromosome was constructed and this map was compared with the standard map of Brassica rapa. The main conclusions were as follows:1.2294 pairs of new Brassica SSR primers were designed from public database. They were named as "BrGMS" basis of different sources.262 pairs SSR markers in A3 chromosome published showed polymorphism between two parents (No.2127-17 and ZhongYou821). The SSR sequences of these primers had repeat motifs from Dinucleotide to pentanucleotide. The most abundant repeat motifs were dinucleotide and trinucleotide repeats. Among the dinucleotide repeat motifs, more AG dinucleotide repeats, followed in abundance by AT and AC repeats, GC repeats are extremely rare. Among the trinucleotide repeat motifs, a higher frequency of AAG repeats was identified.124(47.3%) pairs of primers which polymorphism in two parents were identified.The repeat length of 262 pairs SSR markers in A3 chromosome between in 20bp-24bp; The repeat length of 22bp of SSR primers have largest number and highest polymorphism, accounting for 79.0% and 71.0%.2. Analysis the DH population genotypes with 124 polymorphic SSR markers selected and based on the LOD>7.0, a high-density genetic linkage map in A3 chromosome was constructed by using JionMap3.0,which including 76 SSR markers, covering 145cM in total with an average interval of 1.90cM between adjacent loci.3. The results of comparison between the linkage map of Brassica napus and the standard map of Brassica rapa showed that A3 of Brassica napus and R3 of Brassica rapa had synteny. Furthermore,21 pairs SSR markers had some homologous regions in R3 chromosome of VCS_DH population,18pairs SSR markers had some homologous regions in R3 chromosome of JWF3P population,16pairs SSR markers had some homologous regions in R3 chromosome of CKDH population, respectively.4. The results of comparison between the linkage map of Brassica napus and the physical map of Brassica rapa showed that 47 BACs were mapped to A3 correctly, Among these,40 BACs were included in 31 contigs, the other 7 BACs were not included in any contigs.6 groups of BAC were from the same contig located at adjacent positions in the 40 BACs.The 31 contigs contained 2302 BACs, taken the 7 single BACs together, the 2309 BACs equaled to a physical length of 21.75Mb.