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Meiotic recombination between homologous chromosomes is vital for maximizing genetic variation among offspring. However, sex-determining regions are often rearranged and blocked from recombination. It remains unclear whether rearrangements or other mechanisms might be responsible for recombination suppression. Here, we uncover that the deficiency of the DNA cytosine methyltransferase DNMT1 in the green algaChlamydomonas reinhardtiicauses anomalous meiotic recombination at the mating-type locus (MT), generating haploid progeny containing bothplusandminusmating-type markers due to crossovers withinMT. The deficiency of a histone methyltransferase for H3K9 methylation does not lead to anomalous recombination. These findings suggest that DNA methylation, rather than rearrangements or histone methylation, suppresses meiotic recombination, revealing an unappreciated biological function for DNA methylation in eukaryotes.
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This content will become publicly available on November 25, 2026
mop1 affects maize recombination landscapes by modulating methylation of MITEs near genes in open chromatin
Meiotic recombination generates new genetic combinations and ensures proper chromosome segregation, yet its regulation remains unclear in many species. Here, we show that Mediator of paramutation1 (Mop1), a regulator of DNA methylation, affects the recombination landscape in maize. Highresolution crossover mapping reveals that loss of MOP1 reduces crossover numbers during male meiosis, while the total number in female meiosis remains largely unchanged despite local shifts in crossover distribution. We find that new crossovers occur on miniature inverted-repeat transposable elements (MITEs), particularly in regions with greater genetic diversity. Analysis of DNA methylation and histone modifications, together with gene expression, shows that loss of MOP1 reducesmethylation at MITEs near genes enriched with histone marks linked to open and active chromatin, and downregulates a gene required for chromosome organization. Together, these findings suggest that both chromosome structure and transposonmethylation contribute to recombination control, providing insights into epigenetic control of genetic variation.
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- Award ID(s):
- 2306220
- PAR ID:
- 10666854
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 16
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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