(58(4):310-315)Exploitation and Characterization of EST-Derived Microsatellite Markers in Watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai]

微衛星標誌或稱為簡單重複序列是廣泛使用的一種分子遺傳標誌，目前利用cDNA 和表現序列標幟開發簡單重複序列標誌已使用在許多植物物種，這些標誌可作為基因定位及品種鑑定等重要用途。本試驗自NCBI dbEST 資料庫取下8584 筆西瓜EST 序列，經分析結果已鑑定出546 筆EST 序列攜帶簡單重複序列，共含有585 個表現序列標幟衍生重複序列，其中以三鹼基重複序列為最大宗。本試驗中，從283 筆西瓜EST 序列成功設計重複序列標誌引子，並以市售F1 雜交品種測試重複序列引子偵測能力及評估多型性。試驗結果大約95%的引子可增幅DNA 片段，並且有24 個引子對在22 個測試品種中偵測出多型性。本研究結果將可應用於建立更完善的西瓜簡單重複序列遺傳連鎖圖譜。Microsatellite or simple sequence repeats (SSRs) are molecular markers of choice for many genetic studies. The exploiation of SSR markers from cDNA and expressed sequence tag (EST) has been described for many plant species. These markers are important for genome mapping as well as variety identification. In this study, 546 SSR-containing sequences were identified from 8,584 Citrullus lanatus ESTs, retrieved from the NCBI dbEST database. A total of 585 EST-derived SSRs, with tri-nucleotide motifs most abundant among them, were obtained. Primer sequences flanking SSR motifs were successfully designed from 283 C. lanatus ESTs. Primers were tested for their ability to amplify SSR loci and polymorphism evaluated among commercial F1 cultivars. Approximately, 95% designed SSR primers were successfully used to amplify PCR products and 24 out of 269 SSR markers revealed polymorphisms among twenty-two watermelon cultivars. These EST-derived SSR markers could be a valuable resource for expanding C. lanatus SSR markers and may contribute to establishment of C. lanatus SSR genetic linkage map