Phenolic compounds-enriched extract recovered from two-phase olive pomace serves as plant immunostimulants and broad-spectrum antimicrobials against phytopathogens including Xylella fastidiosa
Marco Greco,
María Fuertes-Rabanal,
Carlos Frey,
Carmine Del Grosso,
Daniele Coculo,
Pasquale Moretti,
Pasquale Saldarelli,
Savino Agresti,
Rosanna Caliandro,
Hugo Mélida,
Vincenzo Lionetti
Affiliations
Marco Greco
Dipartimento di Biologia e Biotecnologie Charles Darwin, Sapienza Università di Roma, Rome, Italy
María Fuertes-Rabanal
Área de Fisiología Vegetal, Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León, Spain; Instituto de Biología Molecular, Genómica y Proteómica (INBIOMIC), Universidad de León, León, Spain
Carlos Frey
Área de Fisiología Vegetal, Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León, Spain; Instituto de Biología Molecular, Genómica y Proteómica (INBIOMIC), Universidad de León, León, Spain
Carmine Del Grosso
Institute for Sustainable Plant Protection, National Research Council (CNR), Bari, Italy
Daniele Coculo
Dipartimento di Biologia e Biotecnologie Charles Darwin, Sapienza Università di Roma, Rome, Italy
Institute for Sustainable Plant Protection, National Research Council (CNR), Bari, Italy
Savino Agresti
Agrolio s.r.l., S.P. 231 KM 55+120, 70031, Andria, Puglia, Italy
Rosanna Caliandro
Institute for Sustainable Plant Protection, National Research Council (CNR), Bari, Italy
Hugo Mélida
Área de Fisiología Vegetal, Departamento de Ingeniería y Ciencias Agrarias, Universidad de León, León, Spain; Instituto de Biología Molecular, Genómica y Proteómica (INBIOMIC), Universidad de León, León, Spain
Vincenzo Lionetti
Dipartimento di Biologia e Biotecnologie Charles Darwin, Sapienza Università di Roma, Rome, Italy; Centro di Ricerca per le Scienze applicate alla protezione dell'ambiente e dei Beni Culturali (CIABC), Sapienza Università di Roma, Rome, Italy; Corresponding author.
The production of extra virgin olive oil generates significant amounts of olive mill waste, whose disposal leads to severe environmental impacts, especially due to the high content of phenolic compounds. In this study, a pomace phenolic extract composed of hydroxytyrosol, tyrosol, verbascoside, and oleuropein was obtained from the liquid fraction of two-phase olive pomace and explored for its antimicrobial properties and potential as plant immunostimulants. The olive pomace extract exhibited a broad range of antimicrobial activity against important phytopathogens, including the bacteria Xylella fastidiosa, Pseudomonas syringae, and Pectobacterium carotovorum, as well as the fungi Colletotrichum graminicola, Fusarium graminearum, and Botrytis cinerea. The extract induced key features of plant innate immunity in Arabidopsis seedlings, including hydrogen peroxide production, phosphorylation of mitogen-activated protein kinase MAPK6, and upregulation of defence genes, such as CYP81F2, FRK1, and WRKY53, suggesting the activation of early signalling cascades leading to the production of indole glucosinolates and salicylic acid. The immune activation pathways induced by the phenolic extract did not always match those triggered by well-known oligogalacturonide elicitors. Notably, pretreatment of adult Arabidopsis and tomato plants with the phenolic compounds-enriched extract primed responses and enhanced their resistance against B. cinerea and P. syringae. Our findings demonstrate the potential to upcycle two-phase olive pomace into plant protectants, offering a promising alternative to reduce reliance on chemically synthesized pesticides in integrated pest management programs.