The collaboration between Frédéric Kerff and the American professor, Daniel Cosgrove, meant that it could be shown that the EXLX1 protein does indeed have expansin activity. ‘And as our protein is more easily handled and manipulated than other proteins in the same family,’ adds Frédéric Kerff, ‘it will be very useful in terms of understanding how these proteins function.’ Another important discovery by the Liège and American researchers: like other expansins, EXLX1 plays a determining role in the process of colonising plant organisms. It is a bit as if these proteins – expansins – were the key used by certain bacteria to enter a plant, in this case through the roots. The research published in PNAS shows, for example, that if the bacteria no longer produces the protein its plant invasive power is divided by 10. And that could well be of interest to farmers, because certain strains of Bacillus subtilis, when they colonise a plant, act as a protective agent against certain microbic diseases. Thus one of theses strains is already being used as biocontrol agent in mulberry tree cultivation for breeding silkworms, in particular. In the future we could imagine selecting strains of this bacteria which over express the EXLX1 protein in order to increase its antibiotic activity. Or improving the effectiveness of another bacterial agent already used as a biocontrol agent by introducing into its genome the coding gene for the EXLX1 protein.