Proteomic profiling and functional dissection of the synaptonemal complex in Arabidopsis thaliana

• Applicant: Dr. Stefan Heckmann
• Subject Area: Plant Cell and Developmental Biology ; Plant Genetics and Genomics
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 543670370

Genetic variation in offspring is assured by homologous recombination during meiosis leading to crossover (CO) formation, i.e. reciprocal genetic exchange between parental chromosomes. During meiotic prophase I, homologous chromosomes are organized around proteinaceous chromosome axes, which in a process called synapsis progressively juxtapose together as transverse filaments proteins polymerize between them forming the synaptonemal complex (SC). In many eukaryotes the SC is essential for CO formation and/or regulates CO patterning (frequency and distribution of CO events). Despite structural conservation of the SC and its impact on CO patterning, compared to non-plant species, we lack a complete picture of the SC composition in plants due to absence of sequence conservation of SC components hampering their homology-based identification. Plant proteomic studies aiming to identify the composition of the SC are challenging due to the limited number of meiotic cells embedded within non-meiotic flower tissues. In a previous project, we performed TurboID-based proteomic profiling of meiotic chromosome axis paving the way for TbID-based proteomic approaches in plant meiotic cells. Among identified novel candidates, one was found to localize to the SC co-localizing with ZYP1 (transverse filament protein of the SC) and its absence leading to abolished SC formation. Accordingly, the candidate being conserved across plant species was preliminarily termed ZYP2. In frame of this proposed work in Arabidopsis thaliana, the two main objectives are: i) dissection of the meiotic role of the new SC-related plant candidate ZYP2 and ii) deciphering of the composition of the plant SC by TbID-based proteomic profiling of the SC. To achieve the first objective, we will study the impact of ZYP2 on axis, SC and CO morphogenesis based on diverse cytogenetic approaches including mutant analysis, immunolocalization of key meiotic proteins, protein-protein interaction studies or meiotic live cell imaging. To achieve the second objective, we will perform MS analysis of affinity purified samples from plants expressing TbID fusion proteins of SC-related proteins. Identified candidates will be prioritized by yeast two hybrid interaction studies and by meiotic chromosome behavior analysis in respective mutants. Both approaches will lead to a better understanding of the composition and function of the SC ultimately aiming to explore new strategies to modify meiotic recombination outcome.

• DFG Programme: Research Grants