Yuxuan Guo

Meiotic recombination in reproductive cells is initiated by DNA double-strand breaks (DSBs) and requires the expression of meiosis-specific genes, yet how the transcription of those genes is regulated in either meiotic or somatic cells remains unclear. Here, using a representative meiosis-specific DMC1 gene promoter as a bait, we identified two DREAM factors TCX5 and TCX6 required for direct repression of DMC1 in somatic cells. Transcriptomic analyses show broad ectopic up-regulation of meiotic genes in tcx5/6 leaves . Consistently, tcx5/6 somatic cells form DSBs and exhibit hypersensitivity to DNA damage compared to wild type. Further genetic analyses reveal that SPO11-1 is dispensable for ectopic meiotic gene activation but essential for the DNA damage response in tcx5/6 somatic cells. Last, we demonstrated that TCX5/6 repress meiotic gene expression through H3K4me3 modification. This finding uncovers an unexpected mechanism for suppressing meiotic recombination in somatic cells, thus preventing genetic diversity and genome instability in organisms.

Meiotic chromosome segregation and recombination, essential for sexual reproduction and evolution, require a specialized gene set. Despite its importance, the transcriptional regulators that directly orchestrate meiotic gene expression remain unidentified in plants. We identify the MuvB core components known from the DREAM complex as key transcriptional regulators of meiotic recombination in Arabidopsis . Loss of DREAM components TCX5/6 and ALY1/2 leads to impaired recombination and fertility defects. Meiocyte-specific transcriptome profiling and genome-wide binding analyses reveal that core recombination genes, including the crossover-promoting helicase MER3, are direct targets. Consistently, MER3 overexpression partially rescues recombination defects in DREAM-compromised plants. These findings establish the DREAM complex components as important regulators of the meiotic program in plants. Given that DREAM dysfunction causes reproductive defects in animals, this regulatory role may be conserved across multicellular eukaryotes.