Discovery of a key player in epigenetic control and plant genome stability

Genetic diversity and biodiversity are essential for species adaptation and for the stability of ecosystems. Adaptation also relies on molecular marks associated with DNA, known as epigenetic marks, which, by influencing gene activation or repression, play a key role in plant development and responses to environmental stress.
A better understanding of the molecular mechanisms underlying epigenetic diversity is crucial for its manipulation and opens up promising prospects in plant improvement. Indeed, it is becoming possible to select advantageous traits without altering the DNA sequence. Epigenetic variability therefore represents a new potential source of phenotypic diversity and a lever for agricultural innovation.
Researchers use Arabidopsis thaliana as a model before applying their findings to cultivated species. They focused on transposons, which are segments of DNA capable of “jumping” from one location to another within the genome.

To protect the genome and preserve its epigenetic stability, a set of proteins ensures that transposons remain inactive and under control. IBM1 normally prevents the accumulation of epigenetic silencing marks on active genes. When IBM1 is no longer functional, this balance is disrupted, leading to the unintended deactivation of certain genes essential for the plant’s vitality. The study of plants lacking IBM1 led to the discovery of another protein, GyrB3, capable of partially correcting these imbalances. GyrB3 is a nuclear protein that combines elements of ancient bacterial enzymes with proteins that modify epigenetic marks. When GyrB3 is defective, transposons become active. This study demonstrated that three key proteins (IBM1, GyrB3, and HDA6) maintain epigenetic stability and regulate transposon activity, working together to preserve gene-transposon boundaries.

The researchers relied on high-throughput sequencing and bioinformatics to decipher these mechanisms. These findings, combined with the team’s expertise, provide a better understanding of the molecular bases of epigenetic variability and open up new perspectives for managing this variability in plants. Ultimately, they could enable targeted manipulation of this variability to control gene expression without modifying the DNA sequence.


Research developed at the Institute Jean-Pierre Bourgin for Plant Sciences.