DNA Markers Detecting Non-glutinous Rice in Glutinous Rice Processed Food

Abstract

To facilitate authentic food labeling, primer sets were constructed to detect contamination with non-glutinous rice in glutinous rice processed foodstuffs. Primers for two DNA markers were designed, because each glutinous rice cultivar has either 23-bp duplication or a 7764-bp insert in the Wx gene. Single PCR products were generated using primer set F12-R14-R15, with a 163-bp fragment obtained from non-glutinous rice, and 138-bp and 186-bp fragments from glutinous rice, due to the presence of the 23-bp duplication. A 190-bp PCR product was generated with primer set F22-R05 from non-glutinous rice, whereas this fragment was not obtained from glutinous rice, which harbors the 7764-bp insert. The PCR detection rates of non-glutinous rice with these DNA markers were evaluated using mixed DNA from rice cakes made in our laboratory. The PCR detection methods exhibited a 100% detection rate at the following sensitivities. F12-R14-R15 detected non-glutinous rice content at levels exceeding 2.5%, in samples containing glutinous rice with the 23-bp duplication. F22-R05 detected non-glutinous rice content at levels above 1.0%, in samples containing glutinous rice with the 7764-bp insert. Commercial products were analyzed, and as a result, these DNA markers were amplified from their DNA. Here, we have demonstrated that these primer sets might be useful for detection of non-glutinous rice in glutinous rice processed foods, made from glutinous rice having either the 23-bp duplication or the 7764-bp insert.