Development And Characterization Of Simple Sequence Repeats From Groundnut

The analysis characteristics of microsatellite, or simple sequence repeats (SSR), and the current status in peanut were briefly reviewed. The paper presented a peanut SSR isolation protocol using hybridization enrichment New SSR DNA sequences were identified, and SSR primers devised, synthesized and used to evaluate the genetic polymorphism of Shandong peanut cultivars.The current peanut SSR isolation protocol was based on multiple enzyme digestion/ligation, mixed biotin-labeled probes and streptavidin coated magnetic beads hybridization capture strategy. Of the 302 white colonies, 119 were found to have unique SSR inserts with number of repeats higher than 4, and totally 166 SSR loci were .identified. The ratio of non-redundant SSR inserts was 43.7%. A hundred and twenty-three (74.1%) of the SSR loci had flanking sequences long enough for primer design, while 43 loci failed to produce SSR primer pairs due to the lack of adequate flanking regions. Perfect, imperfect and compound types accounted for 87.95%, 5.42%, 6.63%, respectively. All of the six probes used (TA,CA,GA,AGA,TGA,ACA) could be directly related to these sequences; the (cgc)4 SSR was an only exceptional case, with a large proportion (94.2%) of the copy number of SSRs ranging from 4 to 30.SSR primers published for peanut, along with those from a strategy involving hybridization enrichment, library construction were evaluated using 12 peanut cultivars mainly from Shandong. Cluster analysis was carried out based on simple matching coefficients between varieties. The results showed that 44 SSR primer pairs were found to produce 176 bands, and 107 (60.8%) were polymorphic. On an average, each primer pair produced 2.43 polymorphic bands in a total of 4 bands. The polymorphic percentage and PIC ranged from 11.1%～100% and 0.245～0.886, respectively. The average of PIC was 0.677.The result of cluster analysis indicated the majority of 12 accessions could be divided into three groups ( I , II, III). The result showed that microsatellites are very useful DNA marker to analyze DNA polymorphism in cultivated peanut.The high genetic similarity of Shandong peanut at DNA level indicated gene bases, which need broadening in cultivar breeding through utilization of elite exotic germplasm resources.