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cpDNA Barcoding by Combined End-Point and Real-Time PCR Analyses to Identify and Quantify the Main Contaminants of Oregano (Origanum vulgare L.) in Commercial Batches

Laboratory of Genomics for Breeding, Department of Agronomy, Food, Natural Resources, Animals and Environment, DAFNAE, University of Padova, Agripolis—Legnaro, 35020 Padova, Italy
Author to whom correspondence should be addressed.
Diversity 2018, 10(3), 98;
Received: 22 July 2018 / Revised: 20 August 2018 / Accepted: 28 August 2018 / Published: 4 September 2018
(This article belongs to the Special Issue DNA Barcoding for Biodiversity)
PDF [1855 KB, uploaded 4 September 2018]


Oregano (Origanum vulgare L.) is a flowering plant that belongs to the mint family (Lamiaceae). It is used as a culinary herb and is often commercialized as a fine powder or a mixture of small fragments of dried leaves, which makes morphological recognition difficult. Like other commercial preparations of drugs and spices, the contamination of oregano mixtures with vegetable matter of lower quality, or the use of generic misleading names, are frequent and stress the need to develop a molecular traceability system to easily, quickly, and cheaply unveil these scams. The DNA-based analytical approach known as cpDNA barcoding is particularly suited for fraud identification in crop plant species (fresh products and food derivatives), and it represents a promising traceability tool as an alternative or complement to traditional detection methods. In the present study, we used a combined approach based on both qualitative and quantitative cpDNA barcoding with end-point and real-time polymerase chain reaction (PCR) analyses to assess the type and degree of contamination in commercial batches of common oregano. In a preliminary qualitative screening, we amplified, cloned, and sequenced a number of universal trnH-psbA- and trnL-barcoded regions, to identify the main contaminants in the samples under investigation. On the basis of these findings, we then developed and validated a species-specific and sequence-targeted method of testing for the quantitative assessment of contaminants, using trnL gene intron assays. Surprisingly, the results obtained in our case study indicated an almost total absence of O. vulgare in the commercial batches analyzed, but a high presence of group I contaminants (Satureja pilosa Velen.), and a moderate presence of group II contaminants (Cistus lanidifer L./Cistus albidus). View Full-Text
Keywords: spices; oregano; species authentication; food traceability; DNA barcodes spices; oregano; species authentication; food traceability; DNA barcodes

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Vannozzi, A.; Lucchin, M.; Barcaccia, G. cpDNA Barcoding by Combined End-Point and Real-Time PCR Analyses to Identify and Quantify the Main Contaminants of Oregano (Origanum vulgare L.) in Commercial Batches. Diversity 2018, 10, 98.

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