Scientists from France's national agricultural research institute (INRA) have described a historical genus of plant virus, evidence of which is still in the genetic information of some crop plants.

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Last month, scientists at INRA published information on a newly discovered genus of virus in the Caulimoviridae family (which includes the cauliflower mosaic virus, as well as other diseases that still affect soybeans, grape vines, rice, tobacco and other agricultural plants). The virus' existence was discovered by comparing the genomes of flowering plants with other types of flora.

The new genus, which the INRA researchers described in the journal Nature Communications, was discovered using new scientific knowledge and tools.

Analysing the genome of 31 plants, including more complex flowering plants and simpler, older organisms, such as moss and green algae, researchers found evidence of a new endogenous (developing from within) virus, but it was only present in the flowering plants' genetic code.

Further scrutiny allowed the scientists to assemble 76 new viral genomes. The INRA team suggested the genetic sequences they discovered could have emerged as the result of interaction "between flowering plants and viruses of a new phylogenetic group within the Caulimoviridae family" long ago.

They dubbed the new virus "Florendovirus." There are different types of florendovirus, the names of which differ depending on their host plant, e.g. 'Vitis vinifera virus', or 'VvinV', for grape vines.

Using the rice genome for further research into the virus' evolution, the scientists traced the Florendovirus back 1.8 million years. They estimated that Florendovirus actually fist appeared between 20 and 30 million years ago.

The INRA team said, "These findings and the description of a new genus of virus constitute a significant scientific breakthrough, boosting knowledge of plants, and notably plants of agricultural interest and the pathogens that affect them. These are major strides in the emerging field of paleovirology."

They said science may well have much more to learn from the ancient virus, as its commonness in plant genomes seems to suggest it played a major role in the evolution of certain plants, possibly through the provision of new genetic material or regulating gene expression.

Though scientists have good knowledge of the insertion of viral elements in animal genomes, this is not the case with plants. The researchers hope that their findings could shed further light on this area, eventually helping combat or prevent contemporary crop diseases.