Molecular and Morphological Variation in a World‐Wide Collection of Safflower

ABSTRACT Safflower ( Carthamus tinctorius L.) is one of the oldest domesticated crops, mainly grown as oilseed in the arid and semiarid regions of the world. Wild relatives of safflower comprise several species distributed worldwide. This study was conducted to investigate the genetic diversity of safflower germplasm and to identify the relationships among some Carthamus species using intersimple sequence repeats (ISSR) and morphological characteristics. Genetic materials consisted of 102 accessions (from 46 different countries) from seven species of Carthamus , including cultivated C . tinctorius and wild species of C . lanatus , C . oxyacanthus , C . glaucus , C . boissieri , C . dentatus , and C . palaestinus . High levels of variation were found for morphological traits; especially seed yield and number of seeds per head. Morphological assessment and clustering could not completely categorize accessions with the related species. Molecular analysis revealed a total of 508 ISSR marker loci, of which 72% were polymorphic with a broad range of 14 to 25 amplified products per primer. Polymorphic information content values ranged from 0.19 to 0.45, with an average of 0.36. Cluster analysis and principal coordinate analysis (PCA) based on molecular data clearly separated accessions according to their species. As expected, C . palaestinus genotype were grouped together with genotypes of C . tinctorius . All genotypes of cultivated species were clustered into five subgroups, mainly based on their geographical distributions. The similarity coefficient between species ranged from 0.34 (between C . tinctorius and C . lanatus ) to 0.90 (between C . tinctorius and C . palaestinus ). The relationship among the regional gene pools of safflower was also discussed.