Maternal Genome-Specific Proliferation of TEs in Dioecious Plant Silene latifolia

Transposable elements (TEs) show extraordinary variance in their presence along plant sex chromosomes but responsible mechanisms are still unknown. To reveal these mechanisms, we studied closely related LTR retrotransposons Ogre that differ in their abundance on the evolutionarily young Y chromosome of the dioecious plant Silene latifolia. One of Ogre families is nearly absent on the Y chromosome, the other two families are ubiquitous on all chromosomes. We found that all Ogre families were mobilized after formation of the Y chromosome which indicates the existence of a mechanism preventing one of Ogres from spreading within the Y chromosome. Comparative study of TEs structure, expression, methylation and siRNA abundance revealed that distinct Ogre families are regulated by variable level of epigenetic silencing in germline and during embryogenesis. Maternal lineage-specific proliferation of TEs is now studied using mutant plants carrying modified Ogre elements. Our findings highlight the epigenetic silencing as a potential crucial factor in parent-of-origin specific proliferation of TEs. These effects are hidden in traditional model species, but they might play an important role in TE-host co-evolution.

Funding: This work was supported by the grant 15-21523Y from Czech Science Foundation.