Genetic and Epigenetic Approaches for the Possible Detection of Adulteration and Auto-Adulteration in Saffron (Crocus sativus L.) Spice.

Saffron (Crocus sativus L.) is very expensive and, because of this, often subject to adulteration. Modern genetic fingerprinting techniques are an alternative low cost technology to the existing chemical techniques, which are used to control the purity of food products. Buddleja officinalis Maxim, Gardenia jasminoides Ellis, Curcuma longa L., Carthamus tinctorius L. and Calendula officinalis L. are among the most frequently-used adulterants in saffron spice. Three commercial kits were compared concerning the ability to recover PCR-grade DNA from saffron, truly adulterated samples and possible adulterants, with a clear difference among them, mainly with the processed samples. Only one of the three kits was able to obtain amplifiable DNA from almost all of the samples, with the exception of extracts. On the recovered DNA, new markers were developed based on the sequence of the plastid genes matK and rbcL. These primers, mainly those developed on matK, were able to recognize saffron and the adulterant species and also in mixtures with very low percentages of adulterant. Finally, considering that the addition of different parts of saffron flowers is one of the most widespread adulterations, by analyzing the DNA of the different parts of the flower (styles, stamens and tepals) at the genetic and epigenetic level, we succeeded in finding differences between the three tissues that can be further evaluated for a possible detection of the kind of fraud.

AFLP and MS-AFLP analysis of the variation within saffron crocus (Crocus sativus L.) germplasm.

The presence and extent of genetic variation in saffron crocus are still debated, as testified by several contradictory articles providing contrasting results about the monomorphism or less of the species. Remarkably, phenotypic variations have been frequently observed in the field, such variations are usually unstable and can change from one growing season to another. Considering that gene expression can be influenced both by genetic and epigenetic changes, epigenetics could be a plausible cause of the alternative phenotypes. In order to obtain new insights into this issue, we carried out a molecular marker analysis of 112 accessions from the World Saffron and Crocus Collection. The accessions were grown for at least three years in the same open field conditions. The same samples were analysed using Amplified Fragment Length Polymorphism (AFLP) and Methyl Sensitive AFLP in order to search for variation at the genetic (DNA sequence) and epigenetic (cytosine methylation) level. While the genetic variability was low (4.23% polymorphic peaks and twelve (12) effective different genotypes), the methyl sensitive analysis showed the presence of high epigenetic variability (33.57% polymorphic peaks and twenty eight (28) different effective epigenotypes). The pattern obtained by Factorial Correspondence Analysis of AFLP and, in particular, of MS-AFLP data was consistent with the geographical provenance of the accessions. Very interestingly, by focusing on Spanish accessions, it was observed that the distribution of the accessions in the Factorial Correspondence Analysis is not random but tends to reflect the geographical origin. Two clearly defined clusters grouping accessions from the West (Toledo and Ciudad Real) and accessions from the East (Cuenca and Teruel) were clearly recognised.