Fraunhofer Institute for Molecular Biology and Applied Ecology IME
Fraunhofer Institute for Molecular Biology and Applied Ecology IME

© Fraunhofer IME | Birgit Orthen

Innovative plant breeding

Plants provide the greatest natural resource for sustainable human development. As well as providing food and feed, plants are used for the production of various raw materials and of renewable energy.

About 12,000 years ago, humans began to domesticate plants: They selected particularly advantageous plants according to their phenotype and replanted their seeds. Over thousands of years, the occurrence of random mutations and recombination evolved these wild plants into our present-day crop plants.

Plant breeding is a never-ending process; even the modern high-performance varieties of our crops are constantly being improved. It is a very time-consuming process, it takes up to twelve years before a breeding line is developed and approved as a new variety after a cross and several selection steps. Consequently, breeding programs address long-term goals.
Given the steady growth of the world's population, climate change and the continuing loss of arable land, the importance of plant breeding is enormous, since it must develop answers to all these global challenges in the form of adapted plant varieties for the agriculture of the future.
The main objectives of modern breeding programs therefore cover a wide range: from strengthening resistance to abiotic and biotic stress factors, to increasing yields and yield stability, improving quality traits and optimizing resource efficiency. Plant breeding also aims to keep pace with customers' changing health and taste preferences.

In close cooperation with various plant breeding companies, the department "Functional and Applied Genomics" conducts extensive research and development activities on the production of new and high-yielding crops by classical and modern breeding methods. The main focus lies on the development and application of breeding-accompanying and accelerating methods such as tilling and molecular markers. In the laboratory, researchers also use innovative genome editing technologies to analyze gene function. The knowledge gained is incorporated into breeding processes and thus plays its part in accelerating the development of new varieties.

 

Tilling

TILLING (Targeting Induced Local Lesions In Genomes) is the targeted screening for induced small gene variations and represents a modern method of reverse genetics in which a gene is inferred from an aberrant function. It combines chemical mutagenesis, a method used in plant breeding for decades, with modern techniques allowing screening of large populations on a molecular level. Tilling is based on the fast growing knowledge of plant genomes and it can be applied to any crop species, regardless of its genome size and ploidy level.
The chemical ethyl methanesulfonate (EMS) is first used to generate point mutations randomly in the plant genome, followed by a high-throughput screening for mutations in the target gene.
The genomes of almost 800 terrestrial plants have already been sequenced and more and more biosynthetic pathways are understood. Thus, many relevant target genes can be identified and by using the tilling technology, for example, the formation of undesirable compounds can be prevented or biosynthetic pathways can be modulated.

For potato, we developed a modified tilling technique taking into account the specific characteristics of potato: autotetraploidy, heterozygosity, vegetative propagation. The gbssI gene (granule bound starch synthase I) that leads to the production of amylose, was used as a model and first target gene. The resulting inactive gbssI allele is now being used in breeding of high-amylopectin potato varieties.

 

Development of molecular markers

Molecular markers are short DNA fragments with a known sequence and location in the genome. Their most important feature is: they are inherited in combination with a specific trait. Thus, this marker can be detected quickly and easily in the seedling, rather than having to wait for the trait itself to be developed in the adult plant. Using molecular markers shortens the long selection process and thus accelerates the breeding process. Different types of markers are used in modern plant breeding, for example SNP markers (single nucleotide polymorphisms). This type consists of point mutations that affect only one base pair.

For potato, we identified a SNP marker for increased anthocyanin content in tubers in a binational project with Chilean researchers.