Deciphering subgenome differentiation and centromere dynamics in Dogroses’ Meiosis Asymmetry

• Applicants: André Marques, Ph.D.; Professorin Dr. Christiane Ritz
• Subject Area: Plant Genetics and Genomics ; General Genetics and Functional Genome Biology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571579009

Polyploidy is common in land plants having strong impact on meiotic cell division and recombination. In species of the allopolyploid dogroses (Rosa sect. Caninae), meiotic cell division is asymmetric. Members of the section are tetra- to heptaploid (2n = 4x, 5x, 6x, 7x = 28, 35, 42, 49) with pentaploids being most abundant. At each ploidy level two chromosome sets form bivalents and are biparentally inherited, while the remaining univalent-forming subgenomes are transmitted only through the egg cell. While other hemisexual systems with uneven ploidy have been described, the Canina meiosis of dogroses is unique among eukaryotes examined so far. In our previous research, we analyzed haplotype-resolved chromosome-level genome assemblies of pentaploid dogroses. We showed the enrichment of centromeres by either the satellite repeat CANR4 or the retroelement Ty3/ATHILA with the satellite repeats dominating centromeres of univalents. In contrast, the highly homozygous bivalent-forming subgenomes were mostly enriched with retroelements. We hypothesize that these structural differences likely drive the asymmetric segregation of complete univalents during female meiosis and influence their meiotic behavior (i.e. premature split in chromatids) during male meiosis. Although our recent findings provided new insights into the unique reproductive strategy of dogroses, detailed investigation on the diversification of centromeres, their regulation and behavior during Canina meiosis are required. In this project we aim to characterize centromere compositions and chromosome segregation in Canina meiosis in dogroses and closely related diploid sexual roses. By using comparative genomics in combination with high-resolution cytogenetics we want to reveal epigenetic regulations of biparentally and uniparentally inherited centromeres and identify the subgenomes involved in pairing and recombination during asymmetric Canina meiosis. Employing mRNA sequencing we will uncover the expression of genes at organ specific manner and identify the candidate genes with potential role during male and female meiosis.

• DFG Programme: Research Grants
• International Connection: Czech Republic
• Partner Organisation: Czech Science Foundation
• Cooperation Partner: Dr. Jana Lunerová