短柱頭菟絲子（Cuscuta reflexa）屬於旋花科，是一種多年生草本植物，廣泛使用於傳統醫藥。菟絲子（Cuscuta chinensis）則是菟絲子屬的另一種植物，兩者在印度當地市場名稱相同，且Cuscuta chinensis已被確認為Cuscuta reflexa 的誤用藥材。本研究開發特異序列擴增（Sequence Characterized Amplified Region, SCAR）標記，用以區分Cuscuta reflexa及其誤用藥材Cuscuta chinensis。選擇特定逢機擴增多型性（Random Amplified Polymorphic DNA, RAPD）DNA片段，Cuscuta reflexa 為690 bp，Cuscuta chinensis為576 bp 。再將得到的DNA片段以特定專一性的引子進行特異序列擴增（SCAR），利用SCAR引子所夾出的Cuscuta reflexa和Cuscuta chinensis DNA片段分別為589 bp 和464 bp 。SCAR引子的檢測效率評估，是將不同比例混合磨成粉末的兩種植物種子，以特定專一性的SCAR引子對DNA萃取物進行擴增及比對。這種為特定物種開發的SCAR標記能夠檢測混合物中低至10%的粉末狀種子檢體。據我們所知，這是第一個對SCAR標記有效性檢測的研究。

Cuscuta reflexa is a perennial herb belonging to the Convolvulaceae family and is widely used as a valuable herbal drug in traditional medicine. Cuscuta chinensis, another species of Cuscuta , is traded under the same name in the local markets and is an identified adulterant of the genuine herbal drug, C. reflexa. In this study, we have developed sequence characterized amplified region (SCAR) markers to discriminate C. reflexa from its adulterant C. chinensis. The RAPD amplicons of 690 bp and 576 bp specific to C. reflexa and C. chinensis, respectively, were selected. The RAPD bands were converted into SCAR by designing specific internal primers (SCAR primers) for these sequences. The SCAR primer sets amplified 589 bp- and 464 bp-sized SCAR markers from C. reflexa and C. chinensis genomic DNA, respectively. The detection efficiency of designed SCAR primers was evaluated by mixing the powdered seed samples of both species in different ratios and amplifying DNAs extracted from these mixed seed samples using designed SCAR primer sets. The SCAR markers developed for a given species were able to detect as little as 10% of the powdered seed sample present in the mixture. To the best of our knowledge this is the first ever study that reports the detection efficiency of SCAR markers.