Developing new SSR markers in walnut

It is necessary to have many polymorphic SSR (Simple Sequence Repeat) markers to construct a genetic linkage map in walnut. However, there are no adequate number of SSR markers in the literature. Therefore, the main objective of this study was to develop novel SSR markers for further genetic linkage mapping studies in walnut. For this purpose, a total of 200 SSR primer pairs were designed from bacterial artificial chromosome end sequences (BES-SSR) deposited in Genbank. All the SSR loci were tested for amplification and polymorphism in 16 local and foreign cultivars. A total of 190 (95%) SSR loci were amplified successfully and 92 were polymorphic. Polymorpphic loci produced 324 alleles ranging between 2 to 11 with an average of 3.6 alleles. primer pairs from J. regia were designed and 190 primers (95%) had successfully amplification patterns. Polymorphism information contents (PIC) varied from 0.06 to 0.87 with an average of 0.42. The dendrogram separated local and foreign walnut cultivars in two groups. In conclusion, 92 polymorphic SSR markers were developed in this study to use them in further genetic studies in walnut. Key Words: Walnut, J. regia. SSR, microsatellite