Saffron (Crocus sativus) is an autotriploid that evolved in Attica (Greece) from wild Crocus cartwrightianus

Abstract

Crocus sativus is the source of saffron, which is made from dried stigmas of the plant. It is a male-sterile triploid that ever since its origin has been propagated vegetatively. The mode of evolution and area of origin of saffron are matters of long-lasting debates. Here we analyzed chloroplast genomes, genotyping-by-sequencing (GBS) data, nuclear single-copy genes, and genome sizes to solve these controversial issues. We could place 99.3% of saffron GBS alleles in Crocus cartwrightianus, a species occurring in southern mainland Greece and on Aegean islands, identifying it as the sole progenitor of saffron. Phylogenetic and population assignment analyses together with chloroplast polymorphisms indicated the wild C. cartwrightianus population south of Athens as most similar to C. sativus. We conclude that the crop is an autotriploid that evolved in Attica by combining two different genotypes of C. cartwrightianus. Vegetative propagation prevented afterwards segregation of the favorable traits of saffron.