The success of plant breeders is no longer to be left to chance. Scientists at the University of Hohenheim are working hard on the development of tools for predictable plant breeding. Using genome analyses, the researchers hope to discover sought-after genes in order to enable plant breeders to select the plant properties they require in a time- and cost-saving way.
Agricultural products underlie extraordinarily high requirements. A good sugar beet variety must not only provide very large quantities of sugar, but must also be resistant to fungi and viruses. Moreover, the sugar beets must not run to seed, and also contain as low a quantity as possible of sodium, potassium and amino nitrogen. In order to come close to the envisaged breeding objectives in such a complex system, classical plant breeding bases itself mainly on the best experience over time. If plants with one or even several of the sought-after properties are found, they are crossed with plants with complementary properties. All this is done in the hope of creating seedlings that are superior to their parents. Such an approach can be successful, but not always. “We no longer want to rely on such a lottery,” said Dr. Tobias Würschum from the State Seed Breeding Institute (LSA) at the University of Hohenheim.
"Knowledge-based breeding" is the goal of four academic and twelve industrial partners in a research consortium entitled GABI-GAIN. GABI stands for "Genome analysis of the plant biological system", and shows where the researchers intend to start their investigations. Using molecular markers, scientists and breeders hope to gain detailed insights into the genetic architecture of agronomically relevant plant properties. They hope to find genes, so-called quantitative trait loci (QTL), which might for example affect the sugar yield of sugar beets, if not determine it to a considerable extent. The task of biotechnologist Würschum and his colleagues at the LSA is to develop suitable biometric methods to identify such QTLs. Their calculations are based on the phenotypic and genotypic data provided by plant breeders.
"We receive data about sugar beets, rape, wheat and maize," explains Würschum adding "we are focusing on properties such as yield, resistance to certain diseases, growth height, dry substance content of certain plant substances." These are the phenotypic characteristics of the individual plants. The genotypic data provided by the breeders relate to the DNA sequences of the plants under investigation, specifically to information about DNA markers. Depending on marker density and field experiment design, the Hohenheim researchers select and develop methods for the biometric combination of the pheno- and genotypic properties of plants. These might be multiline QTL mapping studies, association mapping studies or a combination of the two methods. "Our ultimate goal is to find correlations," said Würschum pointing out that the researchers "are investigating whether plants that have a high resistance for example, also display certain markers." The sought-after QTLs are the genes located in the vicinity of such markers.
“At some time in the future, we envisage that plant breeders will be able to find QTLs themselves. We will provide them with the appropriate tools to do so,” said Würschum, explaining the ultimate goal of his research. One such example that Würschum mentions is the resistance of plants to the root worm, which has become a major risk factor in Germany. If it is known that an exotic maize variety is resistant to this pest, the researchers will be able to search specifically for the genes that confer this resistance and cross these genes relatively quickly into existent breeding materials. The researchers use molecular biology methods to check in the laboratory whether the crosses carry the resistance genes, which saves having to carry out time- and cost-intensive field trials. This modern approach is referred to as marker-assisted selection.
The project partners have around 15 months to bring their project forward as funding through the German Federal Ministry of Education and Research will finish at the end of 2010.
Dr. Tobias Würschum
State Seed Breeding Institute (LSA) at the University of Hohenheim