Marie Fiers is a post-doctoral researcher in phytopathology at the Gembloux Agro-Bio Tech Faculty of Agronomy, University of Liège. She is working on a multidisciplinary project called "Rhizovol" which studies how plants interact with their environment via VOC emissions.
It seems that our garden plants are not totally helpless when threatened. Indeed, the above-ground parts emit scents that interact with the environment in different ways: either attracting pollinators or seed dispersers; or repelling pests as part of a complex and ingenious defense mechanism. Some plants, for instance, are able to produce repulsive odours to deter pests or to lure parasites to deal with assailants. For example, a wasp will ‘smell’ a plant being attacked by caterpillars and fly directly to it to parasitize the attackers, ultimately helping the plant to free itself.
In a more spectacular way, plants have another incredible means of defending themselves by emitting scents to trigger early defence mechanisms in neighbouring plants. This means that a plant under attack produces a certain odour that ‘warns’ its neighbours before they are attacked. How do plants perceive these scents? This is a mystery. There are most likely receptors on the plant that prompt, via cellular mechanisms, a series of biochemical reactions leading to the production of protective molecules.
In her ongoing project, Marie Fiers studies these emission systems as they occur underground. "We want to emphasize the communications occurring between plants at the root level since we believe that VOCs can also be produced by the roots. Our laboratory experiments have successfully demonstrated that a plant will produce different VOCs if is healthy vs infected by fungus. We now have to figure out the purpose of the newly emitted particles. Are they part of a defence mechanism? Do these molecules affect the growth and the reproduction system of the fungus, hence hindering its development? This would constitute an extraordinary defense mechanism for an apparently harmless plant."
For the time being, the researchers on her team have not formulated any hypothesis on the reasons for these emissions. "Intuitively, I would say that once it is attacked, the plant will engage these defence mechanisms. How the molecules are produced and why their production is triggered, we do not know."
The main purpose of this research is to acquire knowledge in the field of molecular emissions for practical applications. Molecules with a protective action on plants could be discovered and used preventively. For example, it could be possible to spray a certain molecule over a wheat field to trigger the defence mechanisms of the plants. The research could lead to improvements in phytotechnology and phytosanitary practices towards a greener agriculture.
For further information, visit l'Unité de Phytopathologie de Gembloux Agro-Bio Tech (French only) or INRA, UMR de Microbiologie du Sol et de l’Environnement (English).
~Lyne Bellemare