315. Alsayied N, Fernández JA, Schwarzacher T, Heslop-Harrison JS. 2015. Diversity and relationships of Crocus sativus and its relatives analysed by Inter Retroelement Amplified Polymorphism (IRAP). Annals of Botany In press June 2015 doi:10.1093/aob/mcv103
Background and Aims: Saffron (Crocus sativus L.) is a sterile triploid (2n=3x=24) cultivated species, of unknown origin from other diploid and polyploid species in the genus Crocus (Iridaceae). Species in the genus have high morphological diversity, with no clear phylogenetic patterns below the level of section Crocus, series Crocus. Using DNA markers, we aimed to examine diversity and relationships within and between Crocus series Crocus species.
Methods: We used a total of 11 Inter-Retroelement Amplified Polymorphisms (IRAPs) primers in 63 different combinations with 35 single-plant accessions of C. sativus and related Crocus species.
Key Results: A total of 4521 distinct polymorphic bands from 100bp to ~4kb were amplified; no fragment specific to all accessions of a single species was amplified. The polymorphic information content (PIC) values varied from ~0.37 to ~0.05 (average 0.17±0.1) and the major allele frequency averaged 0.87. High levels of polymorphism were identified between accessions of the six Crocus series Crocus species related to C. sativus, with further variation between the species. In contrast, no polymorphisms were seen among 17 C. sativus accessions obtained from across the world from Kashmir through Iran to Spain.
Conclusion: In contrast to the intraspecific variability seen in other Crocus species, C. sativus has minimal genetic variation, and we conclude that the triploid hybrid species has most likely arisen only once. Our data show that saffron is an allotriploid species, with the IRAP analysis indicating that the most likely ancestors are 30 C. cartwrightianus and C. pallasii subsp. pallasii (or close relatives). The results may facilitate resynthesizing saffron with improved characteristics and show the need for conservation and collection of wild Crocus.
Keywords: Crocus, Saffron, IRAP, Retrotransposons, Markers, Crops, Polyploidy, spices, selection, crops, triploid, domestication.