In plants, like all sexually reproducing organisms, the development of an embryo requires the fusion of two gametes. These two gametes, the egg cell from the mother and the sperm from the father, each carry one copy of the genome, which together form the genetic makeup of the offspring. However, while the egg cell is essentially like any other somatic cell in the plant, the sperm cell is highly specialized. It has lost most of its cellular machinery and its DNA has undergone extensive modifications.

One of the most important modifications that happen in the paternal genome is the reprogramming of the epigenome. The epigenome is a chemical layer that sits on top of the DNA sequence, which controls how the information on the DNA is read. While these marks are faithfully transmitted through mitosis as cells divide, they must be partially erased in the gametes to allow for the creation of a new and unique organism.

In sperm cells, this reprogramming event is particularly extensive and specific. While most marks are erased, some marks in specific regions of the genome are retained. This ensures that the information necessary for seed germination and seedling establishment is preserved, while allowing for all the other marks that specify plant traits to be reshuffled.

How this remarkable feat is achieved has been the subject of intense research in recent years. A new study, published in the journal Nature Plants, sheds new light on this mechanism by revealing how a protein called DEMETER specifically targets and removes the marks that must be erased.

The researchers used a combination of genetic, molecular and biochemical approaches to show that DEMETER is specifically recruited to the regions of the genome that need to be reprogrammed in sperm cells. Once there, it acts like a molecular eraser, removing the marks that were put in place during the life of the plant. This ensures that the sperm cells carry the correct epigenetic information for the next generation.

This work provides a crucial insight into how plants ensure that their offspring have the right epigenetic start in life. It also opens up new avenues for investigating how the epigenome is regulated in other organisms, and how it contributes to the diversity and adaptation of plants.

Key findings

* DEMETER is a key regulator of epigenetic reprogramming in sperm cells

* DEMETER specifically targets and removes the epigenetic marks that must be erased

* This ensures that the sperm cells carry the correct epigenetic information for the next generation