Two-phase olive pomace is enriched in oligosaccharides activators of plant immunity

The production of olive oil results in significant amounts of two-phase olive pomace, which is frequently disposed of in soil, causing detrimental impacts on both agriculture and environment. Additionally, climate change intensifies plant diseases and causes increased application of harmful phytochemicals in agricultural practices. The industrial process of olive oil extraction could promote the accumulation of bioactive molecules in olive pomace as the self-harm signals naturally generated upon pathogen infection, referred as damage-associated molecular patterns. In this study, a green process was used for the extraction and characterization of a fraction enriched in cell wall oligosaccharides from the olive pomace. The obtained fraction elicited plant innate immunity in Arabidopsis seedlings, including the phosphorylation of mitogen-activated protein kinases and the upregulation of defense genes. Our results indicate that extracted elicitors protected Arabidopsis and tomato against Botrytis cinerea and Pseudomonas syringae. These natural elicitors can be used to reduce the large use of pesticides into an integrated pest management program, promoting circular economy.