Genetics of Safflower Domestication

Carthamus tinctorius L. (safflower) is a drought tolerant crop that is cultivated throughout the world for its flowers and high quality seed oil, especially in third world countries. It is believed to have had a single origin of domestication from its wild progenitor, Carthamus palaestinus Eig., dating to ca. 4000 years ago. Safflower shares a most recent common ancestor with Helianthus annuus L. (sunflower) dating back to approximately 40 million years ago. These two members of the Compositae have been independently domesticated for similar purposes and can thus serve as parallel systems for studying the accelerated evolution of domestication-related traits. The genetic architecture of domestication-related traits has been investigated in sunflower, but virtually nothing has been known about these traits in safflower. Through genetic mapping, QTL mapping, and comparative mapping with other important crops within the Compositae, I describe the genetics of safflower domestication, illustrate localized patterns of macrosynteny throughout the Compositae, and provide preliminary insight into whether parallel phenotypic evolution in both sunflower and safflower was driven by selection on homologous genomic regions.