Combination of SYBR Green II and TaqMan Probe in the adulteration detection of Dendrobium devonianum by fluorescent quantitative PCR

Summary ‘Zipi F engdou’ is a restorative food made of the stem of D endrobium devonianum , P axt., whose high commercial value presents the constant risk of adulteration with cheaper ‘ F oudou’ products made from other D endrobium species. Therefore, this study developed two assays capable of detecting D . devonianum based on SYBR Green II and T aq M an probe real‐time PCR . By performing the diagnostic real‐time PCR based on SYBR Green II , two DNA fragments (163 and 159 bp) were specifically amplified from the internal transcribed spacer ( ITS ) region of D . devonianum . The average cycle threshold ( C t ) values of two D . devonianum samples collected from different C hinese provinces were shown to be 16.65 for ITS 1‐4 and 16.38 for ITS 2‐1, which were significantly ( P  < 0.001, SPSS) different from those of the reference D endrobium species used as adulterants of ‘ Z ipi F engdou’ (34.94 for ITS 1‐4, 34.67 for ITS 2‐1). Moreover, in the assay based on T aq M an probe real‐time PCR , two T aq M an probes were designed and tested for the quantitative detection of D . devonianum in commercial samples labelled as ‘ Z ipi F engdou’. As a result, this assay specifically and sensitively distinguished the processed F engdou’ sample of D . devonianum from those of adulterant D endrobium species.