🍓 The strawberry harbors an extraordinary genetic heritage

Reconstructing the origin of cultivated plants often represents a real puzzle for scientists. Indeed, many species, like wheat or precisely the strawberry, possess genomes resulting from the fusion of several ancestral genomes. These events, called polyploidies (see explanation at the end of the article), occurred millions of years ago and have profoundly shaped the diversity of our crops. In the absence of usable fossils, precisely understanding the unfolding of these mixtures remains challenging.

A research team has developed an innovative computational approach. It relies on the analysis of repeated DNA sequences, retrotransposons, which accumulate in a specific manner over evolution. By comparing their patterns on chromosomes, it becomes possible to reconstruct the steps of genome fusion. Published in Horticulture Research, this technique was first successfully tested on plants such as cotton.


When applied to the cultivated strawberry, this method revealed a very rich evolutionary history, in several steps. The genome of this plant comes from three successive fusions that occurred between 0.8 and 4.2 million years ago. Four distinct subgenomes were identified, revealing close links with known diploid species like Fragaria vesca. These observations challenge some previous models and indicate that now-extinct ancestors likely contributed to this architecture.

This approach opens up perspectives for many other crops. Plants like wheat or sugarcane also have elaborate polyploid genomes. Better understanding their internal structure allows for improved mapping of genes of interest and accelerates plant breeding programs. It is thus a valuable tool for connecting fundamental research with the demands of contemporary agriculture.

Polyploidy, driver of plant diversity

A large number of plants we cultivate owe their existence to a phenomenon called polyploidy. This corresponds to the duplication of chromosomes, often following hybridization between different species. This genetic doubling provides the new plant with increased genetic richness, which can favor its adaptation to new environments.

This process is widespread in the plant kingdom. It has played a major role in the emergence of cereals like wheat or tubers like potatoes. The plant resulting from this fusion inherits traits from both parents, and its larger genome can then evolve with some autonomy. This partly explains the great diversity of forms and flavors on our plates.

When genomes fuse, they do not mix entirely. Rather, they form subsets called subgenomes, which coexist and interact. Each partially retains the identity of its ancestor. Understanding this internal architecture is crucial for breeders, as it influences the expression of genes related to yield, disease resistance, or nutritional quality.

Identifying these subgenomes in ancient plants like the strawberry allows tracing the evolutionary paths taken over millions of years.