Sunflower Domestication

 

Functional Studies of Domestication Genes

Tracing the Assembly of A Domestication Syndrome In Ancient DNA

Analyzing the distribution of domestication alleles in extant samples provides an entry point for resolving conflicting hypotheses about when and where plants species were first cultivated (e.g. Blackman et al., 2011). By harnessing the power of high throughput sequencing technologies, it is also now possible to obtain significant amounts of DNA sequence from archaeological samples.  Consequently, researchers can now observe changes in traits despite being unable to directly measure them on archaeological remains because it is possible to follow the frequencies of alleles known to contribute to these traits over historical time. 


Sunflower has an excellent archaeological record over the past 4000 years, and our knowledge of the genes contributing to the origin of domesticated sunflower is ever growing.  Thus, in collaboration with Tom Gilbert and Nathan Wales at the University of Copenhagen, Bruce Smith and Robert Costello at the Smithsonian, and Kristen Gremillion at Ohio State University, we are beginning to mine the genomes of these samples with the ultimate goal of developing a timeline over which domestication traits arose and spread in North America. 

Carbonized sunflower achenes from the Late Woodland period

Sunflower was domesticated ~4000 years ago by Native Americans in Eastern North America.  Through this process, it was transformed from a highly branched, many headed plant with small seeds into the unbranched crop plant with a single head containing large oilseeds.  Through evolutionary and functional studies, we have previously identified several candidate genes that contributed to this process.  Identifying domestication alleles has already led to novel insights into how gene duplications may contribute to the evolution of novelty (Blackman et al., 2010, see Gene Family Evolution).   The newly available sunflower genome will greatly expand our capacity to discover more of these domestication genes as well as understand more about sunflower’s complex history and the evolution of development in general.  Current projects are focused on determining the molecular and developmental functions of domestication alleles affecting sunflower life history and growth.