Research

Sugar beet (Beta vulgaris ssp. vulgaris) is a young crop plant that originated from wild sea beet (Beta vulgaris ssp. maritima), a coastal plant native to Western and Southern Europe. It has been shown that transposons have influence onto the genome structure and gene functionality of beets. Of the many different repeats contained in a genome, only a small subset is intact and fully functional. However, this small portion may have a huge impact on the genome and as consequence on the phenotype as well. By creating alternative splicing patterns, introduction of novel promoters, change of gene regulation or simply by inactivation of gene function. Thus, the genome is constantly in motion: Transposons get inserted into new positions in the genome; thereafter, selection and mutational processes act upon them. Repeats disrupting crucial functions will disappear quickly, while other elements which are neutral or even beneficial will stay on. By comparing different genomic sequence data of domesticated beets and their wild relatives, we assess the mutagenic events that took place in the beet genome in the recent evolutionary past and explore the role that transposons have played in the evolution of the beet genome. Advances in the repeat-related knowledge of the beet genome may discover new insights about recent transposon evolution and will provide a foundation for further improvements of beet as a crop plant.

Abstract Domestication and diversification are the driving forces to generate the wide variety of currently available crop plants. Diversification of cultivated beets has resulted in four cultivar groups of very different phenotypes, i.e. leaf beets (chard), fodder beet, table beet, and sugar beet. The proposed research will address the question if domestication of beet crops occurred only once or multiple times. It will be investigated how the genomes of the different beet crops are related to each other. We will aim for the identification of diversification genes in order to understand the molecular basis of the phenotypic difference of the cultivar groups. To address theses goals, we will comprehensively search for genomic regions under artificial selection in beet crops. Whole-genome sequencing data will be generated, followed by an analysis of the data using cultivar-specific reference genomes (existing or newly prepared) and statistical interpretation of population differentiation. High-resolution mapping and subsequent characterization of genes will be performed to nominate candidate genes that are crucial for the diversification of beet cultivar groups. In summary, CultiBeet will create important knowledge on the domestication history of beets and will identify the pivotal genes which are involved in beet crop diversification. The experimental setup and computational analyses may serve as a general paradigm for crop diversification studies. Primary researchers involved The project will be jointly led by Ass. Prof. Dr. Juliane Dohm and Prof. Dr. Heinz Himmelbauer.

Sugar beet (Beta vulgaris) is an important crop plant in Austria. Three million tons of sugar beets are harvested each year, sufficient to meet Austria´s yearly demand for sucrose. In the context of BeetSelect, we propose whole-genome sequencing of 500 wild and cultivated beets in order to fully characterize the genetic variation of beets at the molecular level. In the sugar beet genome, we will identify artificially selected genes, i.e. domestication genes, at single-gene resolution. Sequencing data from sea beet, regarded as the ancestor of all beet crops, will reveal inter-population gene flow and will identify genes under natural selection. Rapidly evolving are those genes that allow sea beets to cope with biotic or abiotic stress; the corresponding resistances are frequently not found in sugar beets. Taken together, the proposed work will provide a very accurate picture of the genome architecture of beets. The data will help to understand how artificial and natural selection has shaped the beet genome, which regions are affected by selection, and which genes they contain. Lastly, molecular information on genes underlying selection will provide important information for designing informed breeding strategies for targeted improvement of beet crops.