Ending a period of "bad luck" for clover researchers, scientists report finding the gene that turns ordinary three-leaf clovers into the coveted four-leaf types. Masked by the three-leaf gene and strongly influenced by environmental condition, molecular markers now make it possible to detect the presence of the gene for four-leaves and for breeders to work with it.The results of the study, which also located two other leaf traits in the white-clover genome, were reported in the July/August 2010 edition of Crop Science.
The other leaf traits, the red fleck mark and red midrib, a herringbone pattern that runs down the center of each leaflet in a bold red color, were mapped to nearby locations, resolving a century-old question as to whether these leaf traits were controlled by one gene or two separate genes.
White clover has many genes that affect leaf color and shape, and the three in the study were very rare. These traits can be strikingly beautiful, particularly if combined with other, and can turn clover into an ornamental plant for use in flower beds.
"This is a great time to be involved in white clover breeding" said Wayne Parrott, the senior researcher of the study at the University of Georgia. "We now have the tools to make it easier to breed important traits in this species which has historically proven to be a challenging plant to work with. In addition, we can hasten the development of new white clover cultivars bred for a variety of uses by screening new generations of plants for traits of interest before they even reach the field trial stage, significantly reducing the time and resources needed for new releases of white clover."
The research team, from the University of Georgia and the Samuel Roberts Noble Foundation in Ardmore, Oklahoma, used both modern molecular-based genetics tools and classic breeding methods to solve the mystery of leaf trait inheritance in white clover. The researchers developed two populations of plants, grew them in separate locations, and extracted DNA to analyze molecular markers.
How these leaf traits are inherited and why white clover has so many rare leaf traits and has puzzled geneticists and breeders for many years. This research allows breeders to develop new ornamental varieties. It also sheds light on white clover genetics and evolution, which is still partly a mystery.
Though the four-leaf variety may be best known for bringing luck to its discoverer, white clover is also known a high quality forage, and for its presence as a ubiquitous lawn weed. Researchers are now one step closer to unlocking the genetic mechanisms behind four leaves in white clover and fixing this trait for breeding purposes.
Research is continuing at the University of Georgia and the Samuel Roberts Noble Foundation to map genes involved in other leaf traits and many other white clover traits. The current study was partially funded by the Samuel Roberts Noble Foundation and the Georgia Agricultural Experiment Stations.
- R. M. Tashiro, Y. Han, M. J. Monteros, J. H. Bouton, W. A. Parrott. Leaf Trait Coloration in White Clover and Molecular Mapping of the Red Midrib and Leaflet Number Traits. Crop Science, 2010; 50 (4): 1260 DOI: 10.2135/cropsci2009.08.0457
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