Priming in melon plant induced by FEN560, a novel plant extract elicitorin challenge against biotic attackers

Abstract: This study describes the priming in induced resistance in melon plants treated withFEN560, a plant extract elicitor derived from Trigonella foenum-graecum that was developed forbio-phytosanitary uses. In order to assess the priming occurrence, two cultivars of Cucumis meloL. (susceptible and resistant cultivars) were artificially infected with Fusarium oxysporumSchlecht. f. sp. melonis (FOM), 24h after FEN560-treatment. To evaluate the systemicity ofinduced resistance triggered by FEN560, treatments were performed either by spraying theFEN560-solution or through irrigation. As marker of induced resistance, the changes inlipoxygenase (LOX) and peroxidase (POD) activities were monitored. Besides, a comparativestudy of peroxidase isoenzymes in roots and cotyledons was also performed by iso-electrofocusing(IEF) technique. Results of lipoxygenase and peroxidase kinetic activities and theirisoforms showed that FEN560 markedly induced the resistance in both melon cultivars.Activation of the enzymatic markers also depended on the mode of treatment. Interestingly, theinduced resistance triggered by the foliar treatment was similar to Systemic Acquired Resistancewhile the induced resistance triggered by the treatment of roots was comparable to InducedSystemic Resistance. Nevertheless, the priming was localised on the inoculation site (bioticelicitation), mainly observed in susceptible cultivars.