Effect of Volatile Organic Compounds against fungal and bacterial plant pathogens

Barley is threatened by various edaphic fungal diseases. Common root rot, caused by Fusarium culmorum and Cochliobolus sativus , is one of the major fungal diseases of barley, causing between 9 and 23 % of yield losses. Since several chemicals used for crop protection are being forbidden, new ways of protection are needed. In a previous study, we have shown that barley roots infected by common root rot emitted 23 Volatile Organic Compounds (VOCs) that were not emitted by healthy barley roots. Among VOCs methyl propionate and methyl acrylate applied alone reduced significantly the development of both barley pathogens. The main objective of this study is to evaluate the antifungal and antibacterial activity of both VOCs on a wider range of plant pathogens: Fusarium culmorum , Fusarium graminiurum, Penicillium expansum, Penicilium digitatum and Penicilium itallicum as fungal pathogens ) and Pectobacterium carotovorum carotovorum and Pectobacterium atrosepticum as bacterial pathogens. The evaluation has been made through ELISA microplates with PDB or V8 media. The growth of the pathogen (bacteria and conidia) in the presence of the VOCs was evaluated and compared to a control (same media without VOCs). Methylpropionate showed interesting antibacterial activity with 40% and 96%of inhibition against Pectobacterium carotovorum carotovorum and Pectobacterium atrosepticum, respectively. An inhibition of 77 and 97 % was observed in presence of methylacrylate against Pectobacterium carotovorum carotovorum and Pectobacterium atrosepticum, respectively. Concerning antifungal activity, the results showed that the methyl acrylate inhibted the growth of all tested fungi (the least was P.digitatum by 70%), similarly to methylpropionate (with 50% found in F.culmorum)