Development of molecular markers and linkage maps for the Carthamus species C. tinctorius and C. oxyacanthus

A set of SSR and RFLP markers for safflower (Carthamus tinctorius) and jeweled distaff thistle (C. oxyacanthus) was generated from cDNA and genomic libraries and by mining public and proprietary sequence data-bases. In total, 1412 PCR-based markers and 75 RFLP markers were screened and polymorphic loci were mapped in an intraspecific F-2 population of C. tinctorius and an interspecific BC1 population of C. tinctorius x C. oxyacanthus. The two populations shared one common parent and the resulting linkage maps could be compared for synteny. The level of polymorphism was low in both populations and only 8.2% and 13.7% of the analyzed markers could be mapped in the intraspecific and interspecific maps, respectively. The two maps showed significant colinearity of markers in several regions and an apparent translocation or inversion event on one linkage group. Noticeable segregation distortion was found on one linkage group of the C. tinctorius map and dense clustering of loci occurred on several linkage groups of the C. oxyacanthus map. The two maps represent the first major linkage analysis of Carthamus species. The molecular tools will be useful for a variety of genetic and genomic applications in safflower and its related species and have been used in our laboratory to map a flower color gene in C. tinctorius.