Molecular marker analysis of the genetic variability inside the species Crocus sativus L.

In order to obtain new insights about the relations between phenotypic and genetic variations between different accessions inside the species Crocus sativus L. we carried out a molecular marker analysis by using the AFLP (Amplified Fragment Length Polymorphism) and the MS-AFLP (Methyl Sensitive AFLP, susceptible to the different methylation state of cytosines) methodologies. The first approach gives us the possibility to investigate the variability at the genomic level while with the second one we have the possibility to detect variability also at the epigenomic level (the methylation of the cytosine is the main epigenetic modification of the DNA). The two methodologies have been applied on a core collection made of 27 samples belonging to: 1) different accessions of the species C. sativus from different origins; 2) different species belonging to the Crocus series; 3) different wild type species belonging to the Crocus genus. All the samples before the extraction of the DNA have been grown for at least 3 years in the same environmental conditions in Cuenca (Spain). The AFLP analysis detects that between different species there are high genetic variations at the genomic level: the species C. oreocreticus and C. cartwrightianus have the most similar AFLP profile to C. sativus. On the contrary the differences inside the species C. sativus are extremely low, just few not clear variations have been detected that will need further clarifications in future. The MS-AFLP analysis, conversely to AFLP, reveals the presence of high epigenomic variation not only between different species but also between different accessions inside the species C. sativus. It has been detected that the epigenome is variable not only between accessions from different Countries but also between accessions sampled from several locations of the same Country: all the Spain accessions analysed show different epigenomes. These results give rise to the hypothesis that the epigenetic variations could have an important role in determining the phenotypic differences sometimes observed between saffron accessions. Obviously this hypothesis needs to be confirmed by further experiment.