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Making Headway with Sunflower Genetics

Wednesday, September 17, 2003
filed under: Research and Development

Crop scientists in the U.S. are advancing sunflower genetics research, categorizing and cataloging thousands of sunflower genes. Using this information, scientists are making headway in determining how sunflower genes function and where they are located within the plant.

Ultimately, the genetics groundwork being made on Helianthus annuus (the scientific name that classifies sunflower plant species) will enable sunflower breeders to more efficiently develop new hybrids with improved agronomic and end-use traits.

Steven Knapp, professor of crop and soil science at Oregon State University, along with researchers from the University of California Davis, Indiana University, and the University of Massachusetts, obtained a $4 million research grant several years ago through the USDA Initiative for Future Agricultural and Food Systems Plant Genome Program. The grant was used to study genetic traits in lettuce and sunflower. Lettuce and sunflower are members of the same botanical family (Compositae) the single largest family of plants with 10,000 species worldwide.

Knapp coordinated the sunflower component of the grant, developing a comprehensive gene catalog and gene maps for sunflower. It is estimated that sunflower has about 25,000 genes in its makeup that dictate everything from plant growth, color, size, and pest resistance. It would be difficult to identify all the genes expressed in a sunflower plant, so Knapp and his research staff focused on identifying and cataloging the most important traits, such as genes involved in disease resistance, plant stress, and oil synthesis.

To help sequence sunflower and lettuce, Knapp’s research group worked with PE Celera, the same company that made headlines several years ago with its research in sequencing the human genome. The genome of an organism is its set of chromosomes, containing all of its genes and associated DNA. Genomics refers to the science of mapping, sequencing, and analyzing genomes.

The resulting gene sequences catalogued by Knapp’s research group has been made available for use by others, including botanists, geneticists, plant breeders, oil chemists, and seed companies. The information can help scientists develop traits or hybrids with improved agronomic or value-added traits, such as greater disease resistance, or oil with improved qualities. More details about the Composite Genome Project can be found online:

Knapp’s research group has now begun a related research project that focuses more attention on studying the genomics of vitamin E and fatty acid profiles in sunflower.

“In a nutshell, we are trying to identify specific genes that cause differences in vitamin E and saturated and unsaturated fat content of the oil of sunflower. The purpose is to more efficiently manipulate the genes in hybrid breeding programs,” Knapp says. “While we are not genetically engineering the genes, the information and biomaterials we are generating could be used for that purpose.”

TRAPing sunflower markers

Jinguo Hu, sunflower molecular geneticist at the USDA Northern Crop Science Laboratory in Fargo, is taking Knapp’s research a step further, developing genetic markings within sunflower species to point the way toward particular agronomic or quality traits within the plants.

Once a gene has been marked, researchers can test for its presence in different sunflower lines. Molecular markers allow breeders to bypass the need for screening hundreds of plants for the absence or inclusion of a desired or undesired gene, thus bringing greater efficiency (and less expense) to the process of developing improved sunflower hybrids.

Hu’s research, like Knapp’s, should not be construed as biotechnology; they are not taking the genes of one organism and inserting them into another. Rather, they are identifying where a particular trait is located within a sunflower plant's genetic makeup.

Molecular markers are essentially a tremendously accurate means of “fingerprinting” germplasm, enabling Hu and his research colleagues to

follow traits or genetic makeup in the course of sunflower breeding

efforts— similar to marking a trail to navigate through the woods.

Hu recently developed a novel marker technique for plant fingerprinting, called “Target Region Amplification Polymorphism” or TRAP, for short. In essence, it’s a faster, more efficient method of marking or “tagging” genes that govern desirable crop traits.—Tracy Sayler

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