Allele-specific methylation of <i>MRP3</i> drives mating type determination in a marine diatom
Sex determination mechanisms exhibit remarkable diversity across eukaryotic lineages. In the pennate diatom Pseudo-nitzschia multistriata , sex is determined by MRP3 , a gene with unknown function, which is monoallelically expressed in sexually competent mating type plus (MT+) cells and silenced in MT− cells. Here, we describe an allelic-specific methylation pattern at the sex locus, with a hypomethylated allele specific to the MT+ which is transcriptionally active, while the other hypermethylated MRP3 alleles are transcriptionally silent. In addition, the genome-wide methylation landscape remains stable throughout the life cycle. Treatment with a methylation inhibitor leads to MRP3 activation and partial sex reversal, suggesting an active role of DNA methylation in the sex determination mechanism. Long-read sequencing improved the MT-determining region resolution, highlighting a gene-poor, repeat-rich area that likely represents a primordial MT-determining locus. Our results provide insights into the mechanisms of sex determination and suggest that DNA methylation in diatoms has a more complex role than silencing repetitive regions.
Authors
- Tomohiro Nishimura (ORCID: https://orcid.org/0000-0001-7040-7576)
- Tobias Gerber (ORCID: https://orcid.org/0000-0001-8456-5495)
- Maria Immacolata Ferrante (ORCID: https://orcid.org/0000-0002-8102-8018)
- Alberto Pallavicini (ORCID: https://orcid.org/0000-0001-7174-4603)
- Svenja Mager (ORCID: https://orcid.org/0000-0002-4623-668X)
- Leslie Pan (ORCID: https://orcid.org/0000-0002-2408-4259)
- Marco Sollitto (ORCID: https://orcid.org/0000-0002-0806-1460)
- Andrea Broccoli (ORCID: https://orcid.org/0000-0003-2465-831X)
- Antonella Ruggiero (ORCID: https://orcid.org/0000-0002-0137-0092)
- Francesco Manfellotto (ORCID: https://orcid.org/0000-0001-9032-3783)
- Monia Teresa Russo (ORCID: https://orcid.org/0000-0003-2001-5384)
- Remo Sanges (ORCID: https://orcid.org/0000-0002-5047-9713)
- Viviana Di Tuccio (ORCID: https://orcid.org/0000-0002-3826-7697)
- Federica Di Costanzo (ORCID: https://orcid.org/0000-0002-3978-1372)
Institutions
- Scuola Internazionale Superiore di Studi Avanzati (IT)
- University of Trieste (IT)
- Stazione Zoologica Anton Dohrn (IT)
- European Molecular Biology Laboratory (DE)
- National Institute of Oceanography and Applied Geophysics (IT)
- University of Florence (IT)
- Cawthron Institute (NZ)
Publication Details
- Journal
- Science Advances
- Published
- 2026-07-24
- DOI
- https://doi.org/10.1126/sciadv.adz2992
- Primary Topic
- Diatoms and Algae Research
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Gordon and Betty Moore Foundation