Induction of resistance in Arabidopsis against fungal infections (Hyaloperonospora parasitica) trough the application of a novel inducer

Agricultural crops are the targets of continuous attempts of attack by biotic stress factors such as fungi, bacteria, insects and viruses. Among them, fungal diseases are responsible for the greatest yield loses in both horticultural and fruit trees crops. In the event of a fungal attack, the resistance or susceptibility of the plants to restrict infection will depend on the magnitude and the speed of activation of their defence mechanisms. Furthermore, the ability of plants to combat disease is not attributable to any single biochemical defence strategy, but to a combination of inducible biochemical reactions that produce toxic substances to the pathogen and structural characteristics that act as physical barriers to avoid entrance and spreading of the infection. With this in mind, Bioiberica, S.A. R&D Department has developed Optimus, a new alternative product that elicits the plant’s defensive response by stimulating salicylic acid signalling pathway and the accumulation of structural defence polymers. The main objective of the work is to confirm the protection capacity of Optimus against fungal infections by preventive and curative treatments and comparing it to an untreated control and to a standard chemical fungicide. This study evaluated the mode of action of the product against a biotroph fungus in the model plant Arabidopsis thaliana. Results from the experiment showed an effective fungus protection by Optimus, both preventively and curatively applied, by activating PAL enzyme and intermediaries in the shikimate pathway, mainly flavonoids, cinnamic acid and salicylic acid. Additionally, all products treatments have induced the accumulation of callose papillae 3 days after the fungus inoculation, but none of them stimulated callose accumulation in the absence of infection. These findings confirm the effectiveness of the product on protecting against fungus infections previously observed on a variety of agricultural crops in commercial field trials.