P-117 - Harnessing microalgae for sustainable pest and disease control

Chemical plant protection products (PPPs) are commonly used to prevent crop losses caused by pests and pathogens. However, due to the adverse effects of chemical PPPs on human health and the environment, there is an urgent need for sustainable alternatives. One promising alternative is the use of plant defense elicitors (PDEs) that trigger induced resistance (IR) against biotic and/or abiotic stresses. Microalgae have promising PDE characteristics for agricultural applications. Research has shown that microalgae can trigger plant resistance against phytopathogens by the induction of key plant defense enzymes such as chitinases. Furthermore, there is growing evidence that algae can enhance plant resistance against insect herbivores, but data are still scarce in this regard. In this context, we assessed different microalgae for their plant defense-eliciting activity in Arabidopsis thaliana and tomato (Solanum lycopersicum L.). Based on these results, we selected one microalga for further research. Our results showed that the application of the selected microalga to the leaves of A. thaliana and tomato resulted in a 50% reduction in symptoms caused by the economically important fungal pathogen Botrytis cinerea, while no direct antimicrobial effect of the microalgae on the pathogen was observed. Our project will continue to explore the potential of microalgae as PDEs, aiming to understand their mode of action and provide essential knowledge of microalgae as novel biological PPPs.