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In multicellular organisms, the exchange of genetic information occurs mainly during sexual reproduction between conspecifics. However, lateral gene transfers (LGT) between distantly related taxa have been observed in some cases, but their frequency and evolutionary importance remain controversial. In this article, by comparing many grasses genomes researchers found that large blocks of DNA containing functional genes recurrently passed laterally among distantly related species. Some of these genes are functionally expressed in the recipient species, expanding their genetic toolkit. The spread of functional genes across grasses with distinct physiological and ecological adaptations may therefore represent a significant evolutionary force in this globally important group of plants.

59 lateral transfers of genes identified in A. semialata

By using rigorous phylogenomic analyzes of genomic data from 146 grass species, the authors discovered 59 LGTs in the nuclear genome of Alloteropsis semialata, involving at least nine different donor species. These LGTs belong to 23 laterally acquired genomic fragments that accumulated during the diversification of this taxon. The majority of the 59 LGTs of A. semialata are expressed and thus added new functions to the recipient species.

Functional LGTs were also detected in five other grass species, suggesting that this process is likely to be widespread in this group of globally important plants. Lateral gene transfers therefore appear as an overlooked evolutionary force among grass species, and more generally in plants.