When stressed, plants secrete volatile compounds. By studying chemical particles emitted by barley roots infected by two fungi, researchers in Gembloux have discovered molecules that seem to inhibit the progression of these pathogenic organisms. This is a real defense mechanism. These compounds need to be studied before the practical application of this discovery to the agriculture industry. This is a great step forward in the area of phytopathology, because barley production reached 150 million tonnes last year and the diseases that destroy cereal crop production are numerous and devastating. 

Since the 1980s, scientists have discovered that plants secrete volatile particles aimed at other plants or their environment. Some of these molecules have been identified thanks to different tools and researchers have been able to establish that these volatile compounds vary according to the stress situation of the plant. For example, if a small herbivore chews on a leaf, the plant containing this leaf reacts by secreting a series of chemical compounds. “We do not yet know enough about this type of communication in plants. Perhaps some compounds have  other significations  than those known at present. In any event, at the present time, we know that plants communicate their stress by varying the bouquet of these volatile compounds. These compounds can also enable the stimulation of the defense mechanisms of these plants”, explains Professor Haïssam Jijakli, head of the Laboratory of Phytopathology of Gembloux Agro-Bio Tech (University of Liege)

Even more interesting is the fact that these chemical compounds also constitute defense mechanisms for plants which cannot use teeth to defend themselves or run away to avoid danger. Professor Jijakli is trying to use this system to curb, or at least inhibit, plant diseases that damage the agricultural sector by sometimes causing heavy losses.

Between barley roots and mushrooms

It is against this background that the phytopathologist has supervised a study led by Marie Fiers, a French researcher who was then a post-doctoral student at Gembloux Agro Bio-Tech. This research was published in PLoS ONE(1) last June. The study made it possible to establish the interaction of volatile compounds of barley roots (healthy or diseased) and two pathogenic fungi (Cochliobolus sativus and Fusarium culmorum). Both pathogenic fungi, which attack the root first, are the cause of two diseases that are also known to affect the wheat-growing sector, fusariosis and spot blotch disease. They cause a significant reduction in barley crop yields throughout the world (sometimes as high as 10% to 20% during the most devastating years) but they also cause the development of mycotoxins on the ears.

(1) Marie Fiers, Georges Lognay, Marie-Laure Fauconnier, M. Haïssam Jijakli. Volatile Compound-Mediated Interactions between Barley and Pathogenic Fungi in the Soil, PloS ONE, June  2013, USA