LIQUID FRACTION OF TWO-PHASE OLIVE POMACE IS ENRICHED IN OLIGOSACCHARIDES ACTIVATORS OF PLANT IMMUNITY

Olive oil production generates significant amounts of biowastes. Despite they are characterized by a high polluting and phytotoxic degree, they are still mainly disposed directly on the soil, compromising the balance of ecological systems (Foti et al., 2021). The industrial process of olive oil extraction could promote the accumulation of carbohydrate material, which in planta act as bioactive molecules which are naturally generated upon pathogen infection, and are referred to as damage-associated molecular patterns (DAMPs) (De Lorenzo & Cervone, 2022; Swaminathan et al., 2022). In this study, a process was developed for the isolation and characterization of a fraction enriched in cell wall oligosaccharides from the liquid fraction of two-phase olive pomace (Lionetti et al., 2017). Our results demonstrate that the liquid fraction of two-phase olive pomace contains a mixture of arabinose and mannose-enriched oligosaccharides and galacturonic acid oligomers. Extracted fractions were tested as DAMPs in Arabidopsis plants. Our results indicate that isolated elicitors trigger Arabidopsis immune responses and protect Arabidopsis plants against Botrytis cinerea and Pseudomonas syringae, without affecting growth. These natural, non-toxic and environmentally friendly bioactive molecules can be used to reduce the large use of pesticides by integrating the chemicals into an Integrated Pest Management (IPM) program, promoting a circular economy for more sustainable agriculture.