Plant-based products (e.g. herbal supplements and rare spices) recently came under public scrutiny and criticism for wide spread problems of contamination and substitution of advertised ingredients. DNA barcoding, a method that relies on sequencing DNA regions unique to specific plants, can be used for rapid detection of adulterated samples. However, identification of contaminants requires labor-intensive cloning or metagenomic analysis. The aim of this study is to develop a novel molecular fingerprinting method for rapid and inexpensive identification of contaminants in plant-based products. Initial application of the method is focused on saffron, a spice produced from <i>Crocus sativus</i>. We have amplified and sequenced two DNA regions used for plant DNA fingerprinting (ITS2 and RbcL) from saffron and seven known adulterants of saffron. In addition, DNA sequences of the target regions were retrieved from NCBI database for the plants being studied. Multiple sequence alignment of retrieved and sequenced DNA revealed highly conserved and highly divergent regions. We used this information to design pyrosequencing assay to produce pyroprints characteristic of each sample. We are optimizing our assay and testing reproducibility on pure samples, as well as testing sensitivity of our assay by mixing DNA from different plants in specified ratios. We hope that subtracting pyroprint signal of the pure sample from the pyroprint of the mixed sample would allow us figure out the constituents of the mixed sample (and eventually, adulterated product). We are developing computational tools for identification of adulterants based on pyroprints from mixed DNA samples.

Development of a novel DNA-fingerprinting method for identification of adulterants in exotic spices and herbal supplements

251st National Meeting (2016)

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