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Plant Breeding, Genetics, & Genomics

Sunflower Research

Researchers at Vanderbilt University have produced the first detailed description of patterns and levels of DNA sequence variation across the wild and cultivated sunflower gene pools. Cultivated sunflower is one of the world’s most important oilseed crops. Their results indicate that wild sunflower harbors at least as much genetic diversity as has been reported for other wild plant species, whereas cultivated sunflower shows clear evidence of diversity loss due to domestication. This result suggests that the available wild sunflower accessions are likely to be a rich source of genetic variation for the continued improvement of sunflower. Moreover, the results of this work suggest that it will be possible to identify agronomically important genes with a high level of confidence using association mapping approaches.

In related work, Vanderbilt researchers, in collaboration with Indiana University, Oregon State University, and the University of Georgia, mapped genes controlling seed oil traits in sunflower. The results provide evidence for the presence of one or more genes that influence multiple aspects of fatty acid composition in one particular genomic region. Subsequent analyses of patterns of genetic variation across the wild and cultivated sunflower gene pools provided clear evidence that this region of the genome experienced strong selection during the modern era of plant breeding.

Additional publications from these researchers report the results of a set of detailed analyses of genome structure across sunflower species. The results indicate the sunflower genome has experienced the highest rate of chromosomal reorganization reported to date. A follow up study extended these analyses to include additional wild species, and also included an analysis of reproductive barriers between these species in the context of the chromosomal rearrangements that were previously identified. While these chromosomal rearrangements appear to represent strong barriers to gene exchange between species, the results of this work indicate that the relatively young age of these species has resulted in the retention of large genomic regions that are devoid of rearrangements. This suggests that wild sunflower species can be readily exploited for the continued improvement of cultivated sunflower.

NIFA funded the research through the National Research Initiative Plant Genome Program, and seeds for this work were obtained through the North Central Regional Plant Introduction Station in Ames, IA. The researchers published their findings in the 2004, 2005, and 2006 issues of the journal Genetics.

 

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