Simple sequence repeat （SSR） markers in Carya cathayensis

Key words: 
• cash forestry /
• expressed sequence tag-simple sequence repeat （EST-SSR） /
• Carya cathayensis /
• cDNA library

Abstract: Codominant markers are better than dominant ones in genetic studies for their ability to distinguish homozygotes and heterozygotes，but their development is usually costly. There has been no report on application of codominant markers to Carya cathayensis so far，but the cDNA library associated with fat metabolism in Carya cathayensis revealed 43 cDNA sequences characterized by base repeats of simple sequence repeat （SSR） markers，from which 34 pairs of expressed sequence tag （EST）-SSR primers were designed with Primer Premier 5. With an SSR protocol established，these SSR primers were used to analyze DNA of 40 C. cathayensis trees from a natural population in Linan of Zhejiang Province，which are at least 100 m apart from each other. A native PAGE （polyacrylamide gel electrophoresis） design was used to analyze the applicability of the SSR primers in C. cathayensis. Results showed four pairs of primers had no amplification product，three pairs had an amplification product beyond the pre-designed product length，and 27 pairs had clear and stable amplification products. From the 27 pairs，18 pairs amplified 22 polymorphic loci accounting for 47.8% of the total loci amplified. Compared to other dominant markers （RAPD，ISSR，SRAP and AFLP） developed for C. cathayensis，the SSR markers were only high in the percentage of polymorphic loci. Thus，it would be feasible to develop EST-SSR markers in C. cathayensis.［Ch，2 fig. 3 tab. 36 ref.］