Microsatellite markers variation in artichoke and related taxa

Artichoke, Cynara cardunculus L. var. scolymus (L.) Fiori is a diploid outcrossing species, originated in the Mediterranean basin, which has been much appreciated both for its tasty heads and pharmaceutical properties since ancient times. The cultivated and wild cardoon, and artichoke belong to the same species and are freely interfertile. In Italy, some artichoke varieties are cultivated on a large scale, while a high number of landraces is grown on a small scale. Cultivated cardoon is mainly diffused in northern Italy, southern France and Spain. The wild cardoon grows in the Mediterranean Basin, and in Italy is present in central and southern regions. Microsatellite (SSR) markers consist of tandem repeats of di-, tri- or tetra-nucleotide patterns, are frequent and usually well distributed in plant genomes, and can be exploited to develop locus-specific codominant markers, useful for assessing genetic diversity and mapping. Only a few of these markers have been developed to date in artichoke. We could identify 24 new SSRs present in the artichoke genome, using different approaches. Primers were designed on the flanking regions of these sequences, and fragments comprised between 150 and 400 bp were amplified. The presence of allele variants was ascertained in a set of artichoke accessions representative of genetic variation and geographical origin, in some samples of cultivated cardoons from Italy and Spain, of wild cardoons from Italy, Spain, and Greece, and in four wild Cynara allies. Out of the 24 SSRs identified, 22 were polymorphic, while the remaining two were monomorphic. For some of them, a high number of alleles was observed, and in some cases the frequency of the different alleles was related to artichoke morpho-agronomic traits. Private alleles were found for cultivated and wild cardoons, respectively and a relationship with geographical origin was observed.