Format: ORAL

Gil Yardeni1, Thomas Holzweber1, Juliane C. Dohm1, Heinz Himmelbauer1

1 Institute of Computational Biology, Department of Biotechnology, University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria

The majority of flowing plant individuals are co-sexual with hermaphroditic flowers, possessing the ability to self-fertilize. Self-fertilization is however an infrequent mode of reproduction and nearly half of all flowering plants strictly avoid self fertilization through an array of physiological, temporal and genetic mechanisms. Genetic self-incompatibility (SI) systems guarantee the rejection of pollen identified as self based on protein-protein interaction. The response is controlled by an S-locus that contains two linked protein-coding regions, one uniquely expressed in pollen or anther and the other in the pistil. While pivotal in plant reproduction, SI-systems have been characterized in only a handful of species, owing to their limited homology, high sequence diversity and intricate architecture. The Beta vulgaris complex (family Amaranthaceae) includes three subspecies and several cultitypes, among them commercially important crops of temperate climates such as the sugar beet. Species in the genus Beta exhibit complex genetic self-incompatibility that has been lost in varietal populations, and remains little understood from a physiological and genetic perspective. We present an in silico investigation into the genetic basis of SI in B. vulgaris using high-quality genomic resources. We targeted candidates for an RNAse-based SI system, which has the broadest taxonomic distribution among angiosperms and closely related taxa. Specifically, a highly-contiguous long-read assembly and other data were utilized to identify SI candidate genes. We harness the unique features of the S-locus to identify candidates based on phylogenomic relationships, structural features, high heterozygosity and tissue-specific expression. We proceed to explore the highly dynamic evolution of gene structure in the putative S-loci in different beet taxa. The results will provide first hints to an RNAse-based SI system operating in B. vulgaris and provide a foundation for further studies on molecular mechanisms of SI.