title: Diversity and relationships of Crocus sativus and its relatives analysed by inter-retroelement amplified polymorphism (IRAP).
abstract: OBJECTIVE
  Saffron (Crocus sativus) 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, this study aimed to examine the diversity and relationships within and between species of Crocus series Crocus.
  
  
  METHODS
  Eleven inter-retroelement amplified polymorphism (IRAP) primers were used in 63 different combinations with 35 single-plant accessions of C. sativus and related Crocus species in order to determine genetic variability and to conduct phylogenetic analysis.
  
  
  RESULTS
  A total of 4521 distinct polymorphic bands from 100 bp to approx. 4 kb were amplified; no fragment specific to all accessions of a single species was amplified. The polymorphic information content (PIC) values varied from approx. 0·37 to approx. 0·05 (mean 0·17 ± 0·1) and the major allele frequency had a mean of 0·87. High levels of polymorphism were identified between accessions of the six species of Crocus series Crocus related to C. sativus, with further variation between the species. In contrast, no polymorphisms were seen among 17 C. sativus accessions obtained in the region from Kashmir through Iran to Spain.
  
  
  CONCLUSIONS
  In contrast to the intraspecific variability seen in other Crocus species, C. sativus has minimal genetic variation, and it is concluded that the triploid hybrid species has most probably arisen only once. The data show that saffron is an allotriploid species, with the IRAP analysis indicating that the most likely ancestors are 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.
authors.affiliation: Department of Biology, University of Leicester, Leicester LE1 7RH, UK and.
authors.forename: Nouf Fakieh
authors.initials: NF
authors.lastname: Alsayied
authors.affiliation: Laboratorio de Biotecnología, Instituto de Desarrollo Regional, Universidad de Castilla-La Mancha, Campus Universitario s/n, 02071 Albacete, Spain.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Fernández
authors.affiliation: Department of Biology, University of Leicester, Leicester LE1 7RH, UK and.
authors.forename: Trude
authors.initials: T
authors.lastname: Schwarzacher
authors.affiliation: Department of Biology, University of Leicester, Leicester LE1 7RH, UK and phh4@le.ac.uk.
authors.forename: J S
authors.initials: JS
authors.lastname: Heslop-Harrison
mesh_terms: D044822:Biodiversity; D005075:Biological Evolution; D027622:Crocus / Q000235:genetics*; D005819:Genetic Markers; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011110:Polymorphism, Genetic; D018626:Retroelements
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins; D018626:Retroelements
keywords: Crocus sativus; IRAP; crops; inter-retroelement amplified polymorphism; markers; polyploidy; retrotransposons; saffron