Potential of endotherapeutic treatments with pomegranate peel extract to control the olive quick decline syndrome (OQDS) caused by Xylella fastidiosa subsp. pauca

This study describes the antibacterial activity of pomegranate peel extract on the develop- ment of the Olive Quick Decline Syndrome (OQDS) caused by Xylella fastidiosa subsp. pauca strain De Donno. Xylella fastidiosa subsp. pauca is a systemic bacterium that colonizes the xylem tissue of olive trees by blocking them and limiting the correct sap flow of the plant. For six years, from 2016 to 2021, olive trees affected by X. fastidiosa subsp. pauca were treated with a hydroalcoholic extract obtained from Punica granatum fruit peel. High-Performance Liquid Chromatography–Diode Array Detection– Electro-Spray Ionization Mass Spectrometry (HPLC– DAD-ESI/MS) analysis was carried out to identify punicalagins and ellagic acid which are the main antifungal and antibacterial compounds. The research was carried out on a farm in Trepuzzi (Lecce) located in Salento (Italy). Both in vitro and in vivo tests show the effectiveness of the extract tested. Symptom severity was lower on the canopy of treated plants vs untreated olive trees. Molecular biology tests to assess the presence of X. fastidiosa in treated and untreated plants confirm the effectiveness of Pome- granate Peel Aqueous + Ethanol Extract (PPAEE).